Part-Time Hours Calculator
See exactly what dropping to fewer hours — a 4-day week or reduced hours — really does to your take-home pay. Because tax is progressive, your net pay usually falls by LESS than your hours do.
Estimate only. 2026/27 estimate — verify with gov.uk/HMRC; not tax or employment advice. Flexible working requests are subject to your employer's statutory process.
Enter your salary and hours
Your before-and-after take-home pay, and the real cost of the hours you're giving up, appear here.
Why cutting hours costs less than it looks
Income Tax and National Insurance are progressive — the more you earn, the higher the rate on your last pound of income. Your Personal Allowance (the first slice of income that's tax-free) doesn't shrink with your salary, so a pay cut removes income from the TOP of your earnings, where it was being taxed hardest. The practical result: dropping to 80% of your hours very often costs you less than 20% of your take-home pay. This calculator runs your current and reduced salary through the same take-home pay engine used across the site, so the comparison reflects real 2026/27 Income Tax and National Insurance rates — not a rough rule of thumb.