UK Reduced Hours & Part-Time Pay Calculator

Moving to reduced or part-time hours, whether through a formal short-time working agreement, a request to your employer, or simply cutting back your contracted week, changes more than just your gross pay. Tax, National Insurance, pension contributions and student loan repayments all shift too, often by a smaller percentage than your hours fall by. This calculator works out your new gross salary, your new monthly take-home pay, and exactly how it compares to your current pay.

How to use the reduced hours pay calculator

Enter your current full-time annual salary and your current contracted hours per week, then enter the new, reduced number of hours you are moving to. Add your tax code, which defaults to 1257L, the standard code for most employees, your pension contribution as a percentage of salary, and your student loan plan if you have one. The calculator scales your salary in proportion to your new hours, then works out your new take-home pay using standard 2026/27 Income Tax and National Insurance rules.

How the calculation works

Your new gross salary is calculated as your current salary multiplied by the ratio of your new hours to your old hours. A move from 37.5 to 30 hours a week, for example, is a reduction to 80% of your previous hours, so your new gross salary is 80% of your current one. From there, the calculator applies the same approach as our take-home pay calculator, deducting pension contributions first, then working out Income Tax and National Insurance on the resulting taxable salary, and finally any student loan repayment due above your plan's threshold.

A tax code starting with S uses the separate Scottish Income Tax bands, while every other standard code uses the England, Wales and Northern Ireland bands. Our Income Tax calculator breaks down exactly how much tax falls into each band if you want to see the full picture.

Worked example

Take someone earning £32,000 a year on 37.5 hours a week, with a 5% pension contribution and no student loan, who agrees to move to 30 hours a week, an 80% ratio, so a 20% reduction in hours.

Their new gross salary comes to 32,000 × 0.8 = £25,600 a year. On their previous full-time salary, after a £1,600 pension contribution, roughly £3,566 of Income Tax and £1,426 of National Insurance, their take-home pay was around £2,117 a month. On the new £25,600 salary, after a smaller £1,280 pension contribution, around £2,350 of Income Tax and £940 of National Insurance, their new take-home pay comes to around £1,753 a month, a fall of about £365 a month, or roughly 17%, noticeably smaller than the 20% cut to their hours. Their hourly rate itself stays the same at both salary levels, since pay was scaled directly with hours.

Common mistakes when working out reduced hours pay

A common mistake is assuming take-home pay falls by exactly the same percentage as hours worked, without accounting for the fact that Income Tax Personal Allowance and the National Insurance threshold stay fixed regardless of salary. This means a lower salary keeps proportionally more of its value tax-free, so net pay usually falls by less than the hours reduction, particularly for people whose salary stays within the basic rate band throughout. Our UK Income Tax 2026/27 guide explains how the bands and Personal Allowance work in more detail.

It is also easy to forget that pension contributions set as a fixed percentage automatically fall alongside a reduced salary, which can affect long-term retirement savings even though it is not always obvious from a single payslip. Checking your new hourly rate, rather than only your monthly pay, is a useful sense check that your new contract reflects the reduction you agreed to.

Related calculators

To see your full take-home pay breakdown at any salary, including Income Tax, National Insurance and student loan repayments, try our take-home pay calculator. If you want to convert either your current or new salary into an hourly figure to compare against other roles, our salary to hourly calculator does this with holiday and sick days factored in. For a closer look at just the Income Tax portion of your pay, use our Income Tax calculator. If you are freelance or considering leaving employment altogether, our guide to calculating your true freelance hourly rate is a useful next read.