How to Calculate Hours Worked in the UK
Accurately tracking hours worked is essential for both employees and employers. Undercounting means lost wages; overcounting can breach contract or Working Time Regulations. This guide covers every scenario, from standard office hours to overnight shifts and variable weekly patterns.
The Basic Calculation
To calculate hours worked on any given day:
- Convert start and end times to minutes since midnight
- Subtract start from end (add 1440 minutes if end is the next day — overnight shift)
- Subtract break duration in minutes
- Convert remaining minutes to hours and minutes (or decimal hours)
Example: Standard office day
Start: 08:30 (510 mins) | End: 17:15 (1035 mins) | Break: 30 mins
Gross: 1035 - 510 = 525 mins | Net: 525 - 30 = 495 mins
Result: 8 hours 15 minutes = 8.25 decimal hours
Decimal Hours vs Hours and Minutes
Payroll systems typically use decimal hours because they are easier to multiply by an hourly rate. The conversion is straightforward: divide the minutes by 60.
| Hours : Minutes | Decimal Hours | Calculation |
|---|
| 8:00 | 8.00 | 0 ÷ 60 = 0.000 |
| 8:15 | 8.25 | 15 ÷ 60 = 0.250 |
| 8:20 | 8.33 | 20 ÷ 60 = 0.333 |
| 8:30 | 8.50 | 30 ÷ 60 = 0.500 |
| 8:45 | 8.75 | 45 ÷ 60 = 0.750 |
| 7:48 | 7.80 | 48 ÷ 60 = 0.800 |
Overnight Shifts
When a shift starts in the evening and ends the following morning, the end time will be numerically smaller than the start time. Add 24 hours (1,440 minutes) to the end time before subtracting:
Example: Night shift
Start: 22:00 | End: 06:00 (next day) | Break: 30 mins
End adjusted: 06:00 + 24:00 = 30:00 (1800 mins)
Gross: 1800 - 1320 = 480 mins | Net: 480 - 30 = 450 mins = 7h 30m
Break Deductions
Under the Working Time Regulations 1998, workers are entitled to a 20-minute uninterrupted rest break if they work more than 6 hours. Many employers offer 30 minutes or 1 hour paid or unpaid. When breaks are unpaid, the time must be deducted from the hours worked before calculating pay.
Weekly Total and Annual Hours
Sum the daily net hours to get the weekly total. For annual hours:
- Gross annual hours: Weekly hours × 52 weeks
- Net working hours: Gross minus holiday entitlement
- Statutory minimum holiday: 5.6 weeks (28 days for 5-day workers)
- Example: 37.5h × 52 = 1,950h gross. Minus 5.6 × 37.5h = 210h holiday = 1,740h net
Full-Time Equivalent (FTE)
Most UK employers define full-time as 37.5 hours per week (7.5 hours per day). Some sectors use 35 hours (civil service) or 40 hours (some manufacturing). FTE is calculated by dividing actual hours by the full-time benchmark:
Part-timer working 22.5h/week ÷ 37.5h FTE = 0.6 FTE
Part-timer working 28h/week ÷ 37.5h FTE = 0.747 FTE
The 48-Hour Working Time Directive
The Working Time Regulations 1998 (implementing the EU Working Time Directive in UK law, retained post-Brexit) limit average working time to 48 hours per week, measured over a 17-week reference period. Key points:
- The limit applies to the 17-week average, not each individual week
- Workers may voluntarily opt out in writing — the opt-out can be withdrawn with 7 days' notice (or longer period agreed contractually)
- Young workers (under 18) may not work more than 8 hours per day or 40 hours per week, with no opt-out
- Certain sectors (transport, sea fishing, junior doctors in training) have separate rules
Shift Patterns
Common UK shift patterns include:
- Earlies: Typically 06:00–14:00 or 07:00–15:00
- Lates: Typically 14:00–22:00 or 15:00–23:00
- Nights: Typically 22:00–06:00 or 23:00–07:00
- Rotating shifts: Workers cycle through earlies, lates, and nights on a weekly or fortnightly basis
- Continental shifts: 12-hour shifts on a 4-on-4-off or similar pattern
Hourly Pay Calculation
Multiply decimal hours worked by the hourly rate. From April 2025, the National Living Wage is £12.21/hour for workers aged 21 and over. The National Minimum Wage for 18–20 year olds is £10.00/hour, and for under-18s (above school leaving age) is £7.55/hour.
Example: Weekly pay calculation
Hours: 42.5h | Rate: £15/h | Contracted: 37.5h
Normal pay: 37.5 × £15 = £562.50
Overtime: 5h × £15 × 1.5 = £112.50
Total weekly pay: £675.00
Frequently Asked Questions
How do I calculate hours worked from start and end times?
Subtract the start time from the end time, then subtract any break duration. For example: start 08:30, finish 17:15, 30-minute lunch. Gross hours = 17:15 - 08:30 = 8h 45m. Net hours = 8h 45m - 30m = 8h 15m = 8.25 decimal hours.
What is the 48-hour weekly limit under UK law?
The Working Time Regulations 1998 cap average weekly hours at 48, measured over a 17-week reference period. Workers may voluntarily opt out in writing. Young workers under 18 are limited to 8 hours per day and 40 hours per week with no opt-out permitted.
How do I convert decimal hours to hours and minutes?
Multiply the decimal part by 60. For example, 8.75 hours = 8 hours and (0.75 × 60) = 45 minutes = 8:45. Conversely, 8 hours 20 minutes = 8 + (20 ÷ 60) = 8.333 recurring decimal hours.
How are overnight shifts calculated?
For an overnight shift (e.g. start 22:00, end 06:00 the next day), add 24 hours to the end time if it is earlier than the start time. So 06:00 becomes 30:00, giving 30:00 - 22:00 = 8 hours gross. Subtract any breaks to get net hours. Our calculator detects overnight shifts automatically.
What is a full-time equivalent (FTE) in the UK?
A full-time equivalent in the UK is typically 37.5 hours per week (7.5 hours per day, 5 days). Some sectors use 35 or 40 hours. A part-time worker doing 22.5 hours per week has an FTE of 0.6 (22.5 ÷ 37.5). FTE is used for holiday entitlement pro-rating and headcount reporting.
How many working hours are there in a year in the UK?
A standard UK full-time worker on 37.5 hours per week works 1,950 gross hours per year (37.5 × 52). Deducting the statutory minimum 28 days annual leave (210 hours at 7.5h/day) gives approximately 1,740 net working hours per year.
Is there a legal requirement for lunch breaks in the UK?
Under the Working Time Regulations 1998, workers are entitled to one uninterrupted 20-minute rest break per shift if they work more than 6 hours. The law does not require this to be paid, but many contracts provide 30 minutes paid or 30–60 minutes unpaid. The break is separate from daily rest (11 consecutive hours between shifts) and weekly rest (24 hours per week).