by Admin

Recently, I’ve had a couple of requests from users of the site to have a pro-rata calculator on the site, so you can work out what your new pay would be if you go down to reduced hours or enter a job share of some sort. Unfortunately, I’ve not had time to make this new tool, but it is easy to use the existing calculator to work out your pro-rata pay.

For example, if you are working 20 hours a week instead of 37.5:

  1. If you know the hourly rate for the job, use the Hourly Rate Calculator, enter that rate and 20 hours – the calculator will show you the take home pay.
  2. If you just know the annual salary for 37.5 hours a week, first divide the salary by 37.5, then multiply it by 20. Enter this new salary into the normal calculator and it should give you the right information.

According to HMRC, tax, NI etc are all worked out the same whether you worked 37.5 hours to earn the money, or just 20 (or 1!). The above tricks can show you what you need to know until I have time to create a pro-rata calculator.

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None of the content on this website, including blog posts, comments, or responses to user comments, is offered as financial advice. Figures used are for illustrative purposes only.

39 Comments to Pro-rata calculations

  1. Sorry, are you sure your calculations are right?! Your weekly figures seem right but not your monthly ones.

    I work a temporary job for £10.50 per hour for 30 hours a week with no sick pay and holiday pay pro rata. I got a monthly pay slip this week based on 4 weeks, and my gross pay was £1181.25 because I had to drop one day, so for that week I was paid £236.25. They deducted £314.06, £77.66 for NI and £236.40. I walked away with a minty £867.19 which I’m not at all happy with. Was that 20% BR tax?

    But for four weeks at £315 per week, which is correct, I should get £1260 gross – not £1365 as you suggest, surely? So have they overcharged my NI? I’ve queried it with them, quoting the figures I got from your site, but now I’m wondering because your monthly figures seem way off. What else are you taking into consideration there?

  2. Tracey Mitchell on October 3rd, 2009
  3. Hi Tracey,

    I think there are two things going on here, firstly a comparison of weekly and monthly, and secondly the tax your employer has taken off you.

    First thing is to note is that a month is not exactly 4 weeks. 4 weeks would be 28 days, not 30 or 31 – so the monthly value is more than 4 times the weekly value. In fact, the calculator divides the annual figures by 12 to give the monthly figures, and by 52 for the weekly figures. So that’s why 4 times £315 is not £1,365

    Secondly, it seems to me that you have been charged too much tax. If you are new to the job, they may have used “emergency tax”, where they don’t know your tax code. Without your tax code, they can’t give you your personal tax-free allowance, so they have taxed all of your income. I’m sure they will clarify this with you – most employers will correct this for your next payslip, and may even refund you the overcharged amount (so next month might be more than you expect!).

    I hope this helps, and as always your employer should be able to explain your payslip to you!

  4. admin on October 3rd, 2009
  5. Thank you for the explanation.

    I did challenge them about the tax and they then told me I had to complete a P46, in order for them to obtain a correct tax code for me and get me off BR.

    I had given them a P45 from my previous temp role which had had a BR tax code with it (because I had one and because I thought P45s were preferable over P46s!) but I hadn’t noticed the deduction as much because that role was weekly paid. For the last seven years I have also worked on and off for a nurse ‘bank’ for which I have a proper tax code – I don’t see why I can’t pass that on to this current employer, but apparently each new job needs a new tax code!

    (I’ve only been working nineteen years, like!)

    I know for a fact my name is mud with the inland revenue with all my temp roles because they as much as said they’re fed up with giving me rebates!

  6. Tracey Mitchell on October 14th, 2009
  7. Hi, I have a question about tax free allowance. I started my new job in Nov 2010, and thus will only be working 5 months this tax year (1 Nov – 31 Mar). I understand that the current tax free allowance is at £6475. Will I be getting the full £6475 tax free allowance, or will there be some sort of a pro rata calculation (i.e. £6475 x 5/12 = £2698)?

  8. Jin on February 3rd, 2011
  9. Hi Jin,

    If you didn’t have any income between April 2010 and starting your new job in November, you should be entitled to your full allowance of £6,475 for the 2010-11 tax year (although the allowance can be affected by other benefits – see the post on tax codes). Most employers will automatically work out the correct amount for you to take home this tax year, and spread that over your payslips. You may find in April that you take home less than you do now, since your tax-free allowance will be spread over the whole year rather than just 5 months! If you are uncertain, check with your employer’s finance or HR department – they will be able to explain things to you. If you have paid too much tax this year you can normally claim it back from your local tax office.

  10. admin on February 5th, 2011
  11. hi, while you are developing a tool for reduced hours working, please could you consider developing something for reduced weeks working. I am a term time only worker, working 37 weeks per year and would like help to calculate earnings please. thanks

  12. bobby on March 14th, 2011
  13. […] Calculator – I have finally created it and added it to the site. As I have mentioned in an earlier post, pro-rata salary is normally calculated quite easily. For reduced hours, most employers will […]

  14. Pro-rata Salary Calculator added | The Salary Calculator on April 2nd, 2012
  15. Hi Bobby,

    Sorry I missed your comment last year! I have just created a new pro-rata calculator here:

    It asks you to enter full-time hours and pro-rata hours, but you can also enter weeks (the calculation is the same). So, in your example, you could enter 52 into the full-time hours box and 37 in the pro-rata hours box, and it will calculate the salary pro-rata for you.

    I hope this helps!

  16. admin on April 2nd, 2012
  17. If the full-time working hours are 35hrs per week but a person gets a pro-rata bonus of £400 but works 41 contracted hrs per week for the same company, should the bonus go up as it goes down for anyone working less than 35hrs?

  18. Duncan Martin on March 28th, 2013
  19. Hi Duncan,

    It would depend on how the employer works out the bonuses for each of their staff. In my experience, a bonus is often a percentage of the staff member’s normal salary – so if they were getting paid more because they worked 41 hours per week rather than 35, the bonus would be proportionately larger. However, it is possible that the employer might have a cap on the bonus or try to treat additional hours as overtime rather than contracted (and therefore not included in bonus calculations). The HR or payroll department should be able to explain how the bonuses are worked out.

  20. admin on March 28th, 2013
  21. hi
    I receive 700 euro pension a month from Ireland but when I receive it in pounds it is £541.86 I have checked the exchange rate and I am £50. pounds short can you explain please thank you.

  22. john coogan on May 20th, 2013
  23. Hi John,

    I’m afraid I don’t know what would cause that. It is possible that there is a commission fee for changing the currency charged by your pension provider, their bank, or your bank – or maybe some tax is being deducted before it is transferred. I would suggest a first port of call be your pension provider, they might be able to explain why this is happening.

  24. admin on May 20th, 2013
  25. Hello, I am due to start a new job next week. The shift pattern is 4 on 4 off, 12.5 hours per shift at £8 an hour. It’s with an agency so I’ll be paid weekly. I’m trying to work out how much I’ll take home weekly, monthly and annually and how much tax and NI I’ll pay. Due to the shift pattern and it being weekly pay I don’t know how to. Can you help?

  26. Sarah on July 21st, 2015
  27. Hi Sarah,
    I don’t have any experience with this specific situation, but this is how I imagine it will work out. Some weeks you will work 3 shifts and have 4 days off, others you’ll work 4 and have 3 off (which particular days you work will change from week to week, but it’s always either 3 days or 4 days). 3 shifts at 12.5 hours is 37.5 hours in the week, 4 shifts brings it up to 50 hours. Assuming that you get paid each week according to how many shifts you did:
    Go to the hourly wage calculator and enter £8 as the hourly wage, and 37.5 hours. This will give you the amount you’ll earn in a 3-shift week. Now change 37.5 to 50, and that’ll show you what you’ll get in a 4-shift week.
    It’s possible that the agency will pay you same each week, an average of the two amounts – to see this, enter 43.75 (the average number of hours you’ll work) in the hourly wage calculator. This will also give you your effective annual salary (in the Yearly Gross Income column).
    Now, I’m not certain about any of this, and I should point out that it’s likely that your take-home pay may be a little different from this each week – by a few pounds here or there – because tax is worked out cumulatively. Brief version: your tax in a 3-shift week will take into account the fact that the previous week was a 4-shift week, for example. Hopefully, though, this is of some use!

  28. admin on July 21st, 2015
  29. My daughter a staff nurse generally earns £1,700.00 per month she is currently on maternity leave and rather than have 8 weeks full pay them 18 weeks 1/2 pay plus SMP then 13 weeks SMP she asked for her wage to be averaged out she was on annual leave until the 27th june but this months wage is only £700.00 way below her direct debits is this correct please

  30. Sonia gregory on July 26th, 2015
  31. Hi Sonia,
    I’m afraid I don’t have any experience with Statutory Maternity Pay, so I don’t know how it is calculated and how your daughter’s employer might have worked it out. It is possible that her employer has averaged her salary over 52 weeks rather than the 39 that you have listed, that would obviously make the monthly amount lower. I would suggest that in the first instance ask her HR or Payroll department to talk you through the calculations for this month’s payslip – they should be able to tell you how they worked out the amount to pay her. If they can’t help, Citizens Advice will probably be able to offer some assistance too. Sorry I can’t help further!

  32. admin on July 26th, 2015
  33. Hello, I recently asked my employer how my pro rata wage is calculated as I honestly felt I was on a lower wage than my full time work colleagues. I work 22.5 hours per week, The full time wage is £17610 per annum. They sent me the following calculation:

    £17610 x 22.75 ÷ 38.75 = £10338 per annum pro rata (This is indeed the wage they pay me.)

    But your calculator says my wage should be £10612.65? Also I don’t understand the 22.75 either as it is really 22.5 ? Please help. Thanks

  34. Anne on October 23rd, 2015
  35. Hi Anne,
    When I try the numbers £17,610, 22.75 hours per week from 38.75 full-time hours in the calculator, I get £10,338 too – so the calculator matches your employer’s calculations. I’ve tried a few other numbers but I can’t get them to produce the result you got. It’s possible that you left the full-time hours as 37.5, which is what a lot of UK employers consider to be full time – this would make it look like you should get paid more than you do, since your hours would be a slightly larger fraction of that smaller full time amount.

    I’m afraid I don’t know why your employer thinks you work a quarter of an hour each week more than you think you do – I would suggest you check your contract for how long you should be working. Of course, if you are right, your employer might start paying you less (or asking you to work more)!

  36. admin on October 23rd, 2015
  37. Hello

    Thanks so much for your response ! You were indeed correct and I had entered the incorrect full time hours. So my employers calculations are right after all. I can now put this matter out of my mind. Thanks again.

  38. Anne on October 25th, 2015
  39. Hi, are salary questions still being answered here? I see the last one was in 2015..

  40. Ester on October 27th, 2016
  41. Hi Ester,
    If questions are asked, I try to help if I can!

  42. admin on October 28th, 2016
  43. Hello.I have drop from 37.5 hours to 35hours.I have received pay rise over the years as I have been with the company almost 6yrs. I received my letter with change of hours.losing my.night shift allowance of £3650 and a bonus of £1500 that’s spread across the 12 months. I have dropped from £24230 to £17759.which is almost what I was earning when I started in 2011.I find this disheartening and am contesting this figure.
    I was given a formula
    Annual salary/52/37.5×35×52
    I have from £1626 after tax now redirecting £1256.
    Please can you help give me your opinion.

  44. Ini on November 11th, 2016
  45. Hi Ini,
    Sorry to hear about this change!
    It seems that the biggest changes in your salary are actually from losing the night shift allowance and the bonus – this takes you down from £24,230 to £19,080 even if you still did 37.5 hours per week. I believe that is the salary that your employer has put in the formula (which is almost identical to the one the Salary Calculator uses). With the numbers you have provided, I actually get a new salary of £17,808 – which is in fact a bit more than what you have put above, but not much different.
    So the reduction in hours is costing you £1,272 per year (before tax), but the loss of the night shift allowance and the bonus is costing you £5,150 per year, obviously a lot more. If you can find a way to keep those, it will help you to keep your salary up. I’m sure your employer will be able to explain exactly how your new salary is calculated.

  46. admin on November 11th, 2016
  47. Hi I’m really confused my job is making me redundant and have said if we stay until may we will be given an extra £1000 flat rate. However they are now saying as I am part time working 20 hours per week my £1000 will be paid pro rata. I earn 710.69 monthly but cannot work out how much I’m really going to get??

    Please help.

  48. Natalia on November 29th, 2016
  49. Hi Natalia,
    I think the safest thing is for you to ask your employer what your extra £1000 will work out to be, just so you are really clear. However, to work it out I think they will be multiplying £1000 by 20 (the number of hours you work) and dividing by the number of hours that count as full-time (this is probably 37.5). This works out to be about £533. Your normal £710.69 per month is probably not enough to pay tax (although you will pay some NI) – when you get paid the additional £533 you might have some tax deducted because it will increase your earnings that month. Try the normal Salary Calculator with a salary of £710.69 x 12 = £8,528.28 (assuming your £710.69 is before deductions), and then use the bonus tab to enter £533. This should help you see what your take-home will be.
    As I mentioned above, you might pay a little Income Tax on the bonus which the calculator doesn’t show – if your earnings for the rest of the year remain below the income tax threshold, you will get it back so don’t worry.

  50. admin on November 30th, 2016
  51. My question is this. I’ve applied for a role that is workrd out per annum pro rata. So for the year it would be around £17,500 but as its for 8 months only the pro rata amount is £11,653 over 8 months. This might be a silly question but to work out how much the pro rata salary is a month, do I just divide it by the 8 months?

  52. Maria on December 12th, 2016
  53. Hi Maria,
    The short answer to your question is yes :). If you are starting and finishing the job part way through a month, then in those months you’ll probably only get paid for the work you’ve done that month, but in full months your calculation should be correct. It’s possible that your employer might pay you only for the number of working days in each month (some months might have one or two more than others) rather than simply dividing the total salary by 8, but this does not make a huge difference to the monthly pay.
    Incidentally, if you want to work out what your take home pay is likely to be from this job, the best way to do that would be to put in the full salary (£17,500) into the Salary Calculator – this will show you the monthly pay, and the monthly deductions (you will just get this for 8 months rather than for 12). This will be the closest to how your employer will work it out, since they do it month by month. If you finish after 8 months and don’t have another job afterwards, it will mean that you will have overpaid tax – but you will be due a refund of anything you have overpaid.
    I hope this makes sense!

  54. admin on December 12th, 2016
  55. Hello,

    I work 8 hours a day over 4 days every week. I am entitled to 33 days annual leave per year can you tell me my hourly entitlement please? Last year it was worked out as 211.25 but I am sure this is incorrect.

    Many thanks

  56. Gilana on December 30th, 2016
  57. Hi Gilana,
    I don’t know enough about your circumstances to say for sure. 33 days at 8 hours per day is 264 hours. If your entitlement is actually less, because you don’t work full time, then I would assume “full time” means 5 8-hour days per week instead of the 4 you work. In which case, your employer probably works out entitlement pro-rata, i.e. four fifths of 264, which is 211.2 hours. They should be able to explain to you how they work this out, if you are not certain.

  58. admin on December 30th, 2016
  59. Hi I am contracted to 37 hours per week and I am paid 1/12 of my salary each month I have calculated that 37hrs x 52 weeks= 1924 hrs per year decide by the 12 months is 160.33 hrs per month. We do get overtime what I want know is if I work over my 160 hrs each month is the rest overtime as I did 172 hrs last month but didn’t get my overtime

  60. Barbara wilson on June 24th, 2017
  61. Hi Barbara,
    It is normal, with a salaried position, to find that some months you work a bit more than the average and some months you work a bit less, because the number of working days can be different each month. If you work Monday to Friday, and ignoring bank holidays for the moment, there were only 20 working days in April this year but 23 in May. With your salary split evenly during the year, this probably means you were paid more than you worked in April, but less than you worked in May – it evens out over the year.
    If you just worked your normal hours, therefore, it is unlikely that you are due any overtime. Overtime is normally paid when you work in addition to your normal hours – by which I mean things like working on a day that you normally do not, or working a longer day than usual. Working on bank holidays sometimes earns you overtime. Your contract should explain when overtime applies and when it does not – and your employer should be able to clarify if you have any questions.

  62. admin on June 26th, 2017
  63. Hi, I had been working for this company part time 16hours for many years. As a part time worker my Housing Benefit is paid in full to cover my rent.
    A few days ago my employer asked me to cover for another employee on holiday which brings my hours to 20hours a week.
    I really would like to know if it is worth taking the additional hours? Would this affect my HB and goes into pro rata? Please help. My employers are waiting for my decision.

  64. Almaz on November 16th, 2017
  65. Hi Almaz,
    If you use the Hourly Calculator you should be able to enter your hourly wage and 20 hours per week, to see how much you’ll take home in a week if you work the additional hours. You can compare this to your usual 16 hours.
    I’m afraid I have no information about whether this will affect your Housing Benefit. You might find some useful information on or Citizens Advice.

  66. admin on November 16th, 2017
  67. Hi.
    Very handy tools, Thankyou.
    My wife and I each have term time contracts, my wife earns £10 per hour, but is paid over the whole year.
    Recently, my wife had 3 hours off without pay, and she was deducted £30, which at first sounds correct, however she did work an extra 3 hours of overtime, yet got paid less. (Would have been easier to just not deduct 3 hours, but heyho!)
    Should the hourly rate match the actual time off, or should it be based on the lower ‘pro-rata’ rate?

  68. Phill on January 7th, 2019
  69. Hi Phill,
    I’m pleased you find the site useful, thank you!
    I’m afraid I don’t know the answer to your question. As you’ve described it it does sound a bit odd that the two changes don’t cancel each other out. It would be worth checking whether one is the pre-tax change and the other the post-tax change. Your wife’s contract may explain how such variances should be calculated – if that doesn’t help, her employer should be able to explain how they are working things out.
    If you’re not able to get the answer you want there, Citizens Advice has a lot of helpful information about employment.

  70. admin on January 9th, 2019
  71. Hi, I work 37.5 hours a week but get paid monthly 162.5 hours the same each month. Total 1950 per year. I am on a hourly pay. I have been paid like this for 9 years now. As there are 52 weeks and 1 day in a standard year and 52 weeks and 2 days in a leap year am I loosing out. My employer said no as last time I ask was in 2017 which there was 260 working days 1950 working hours but 2018 and this year 2019 there are 261 working days 1957.5 hours.
    Many thanks.

  72. GARY JOHNSON on March 12th, 2019
  73. Hi Gary,
    I’m afraid I don’t know. It sounds like your are on an annual salary, because you get paid the same amount every month regardless of how many working days there were in the month (for example, there were 20 in February but 21 in March this year). Generally, an annual salary means you get the contracted pay, regardless of the number of working days in the year. It might be worth asking your employer again, or speaking to an accountant or Citizens Advice to get a more detailed answer.

  74. admin on March 12th, 2019
  75. My nhs contracted hours are 17.5 per week. We are to recieve a bonus next week of £1300 Pro rata. £1300 is for 37.5 hr week. The past year I have been working overtime every week. Bringing me up to normally between 30 and 35 hrs per week. My question is, is my overtime taken into consideration when working out the pro rata or does it solely go by contracted hours.

    Many thanks

  76. SHARON SLOAN on May 22nd, 2021
  77. Hi Sharon, thank you for your comment. Without knowing the specific details of your employment contact, I would say it’s likely that your overtime would not not contribute to your bonus. However this isn’t necessarily the case, and hopefully you do get a larger bonus which reflects all the hours you worked!

  78. Editor on May 26th, 2021

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