How to use this calculator
This calculator is designed to make a practical work decision clearer. It gives an estimate based on your inputs and keeps salary, time and work-related costs separate so the result is not reduced to one misleading headline number.
What the result can and cannot tell you
| Factor | How to treat it |
|---|---|
| Monthly affordability | The take-home reduction must fit essential costs. |
| Time regained | Extra time off is the central benefit. |
| Workload reality | Reduced pay is weaker if workload does not reduce. |
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Related next-step routes
These follow-on pages keep the same decision practical when the question becomes more specific.
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Estimate how much more salary may be needed to make a five-day job worthwhile against a shorter week.
Methodology and assumptions
Where take-home pay is estimated, the calculator uses the existing WorthMyTime 2026/27 employment tax estimator for England, Wales and Northern Ireland. It does not replace payroll software and does not model every tax-code, pension, benefit or employment-contract detail.
- GOV.UK Income Tax rates and allowances
- GOV.UK employer rates and thresholds 2026/27
- GOV.UK overtime rights
- Acas pay for working extra hours
- GOV.UK holiday entitlement
FAQ
What does four-day week calculator help with?
It helps you compare money, time and working costs so four-day week calculator is judged as a practical work-value decision rather than a headline salary figure.
Is this financial advice?
No. WorthMyTime provides general educational calculators and explanations. It does not give personalised financial, tax, pension or employment advice.
Why does the answer depend on my assumptions?
Working hours, commute days, tax position, pension treatment, bonus reliability and employer policy can all change the result.