48-hour average week calculator
Is someone over the 48-hour average working week? Enter the hours over the reference period, and any days off on holiday or sick, to see their average the way the Working Time Regulations work it out.
The rule used
Read from the same reference data KivoHR’s working time checks use.
The average is the hours in the reference period, plus the hours worked straight after it over as many working days as were taken off on leave, divided by the weeks in the period (Working Time Regulations 1998, regulation 4).
Source: Working Time Regulations 1998, regulation 4, legislation.gov.uk (opens in a new tab), checked 2 Nov 2026
Source: Maximum weekly working hours (opens in a new tab), checked 2 Nov 2026
Our guide to working time rules for rotas covers rest breaks, daily and weekly rest, and night work.
This calculator gives the legal minimum as guidance, not legal advice. For one person’s situation, check their contract, or ask Acas (0300 123 1100, free) or a solicitor.
Rotas that check the law as you plan
KivoHR’s rota warns you as you plan a shift that would take someone over the average or cut into their rest, and its working time report shows who works over 48 hours and who has opted out.
48-hour week questions.
How is the 48-hour week averaged?
Add up the hours worked over the reference period, normally 17 weeks, and divide by the weeks in it. Someone employed for less than that is averaged over the time since they started.
What about holiday and sick days?
They don’t count as weeks of no work. Leave them out, and add the hours from the same number of working days straight after the period. Statutory holiday, sick leave, and maternity, paternity, adoption and parental leave all work this way.
What counts as working time?
Time working, job-related training, paid overtime and unpaid overtime you ask for, working lunches, travel that is part of the job, and time on call at the workplace. Breaks with no work, on call away from work and the commute to a fixed workplace don’t count.
Can someone work more than 48 hours?
Yes, if they agree in writing to opt out. They can cancel it with at least 7 days’ notice, or up to 3 months if your agreement says so. Under-18s can’t opt out.
Can the reference period be longer?
Up to 52 weeks, by a workforce or collective agreement. It is 26 weeks for doctors in training, and for some special cases, such as hospital, care, security or seasonal work.
Do it automatically in KivoHR.
14 days free, no card needed.