What are decimal hours?

Hours as a decimal for payroll: minutes ÷ 60. 30m = 0.50h, 15m = 0.25h, 25m ≈ 0.42h. Multiply by hourly rate for pay.

How do I add hours to a time?

Convert both to minutes, add, and wrap modulo 1,440. Example: 09:30 + 7h45 = 17:15. Use add-duration mode above.

Does it handle overnight shifts?

Yes — when end is earlier than start it assumes next day (toggleable). 22:00→06:00 returns 8h, not an error.

Yes — 2:30 PM, 2:30 pm and 14:30 all parse. Hours must be 1–12 with AM/PM, 00–23 without.

How do I total a week of times?

Convert each day to minutes or decimals, sum, then convert back. Or sum decimals (7.50+8.42+…) and multiply once by rate.

Time & Date · Free tool

Time Calculator

Hours between times, shift lengths and add-duration maths.

What is 22:15 to 06:40 — and is that 8.42 hours for payroll? What is 09:30 plus 7h 45m with a 30-minute break? Time arithmetic breaks normal subtraction because clocks wrap at 24:00 and payroll speaks decimals while rosters speak hours-and-minutes. This time calculator handles both directions: duration between two times (overnight-aware) and add-duration to a start time, with decimal-hour output for timesheets.

Under the hood every time becomes minutes-since-midnight; differences wrap +1,440 minutes when the end is earlier and overnight is allowed. Decimal hours are minutes ÷ 60 to two places — the format payroll systems, freelance invoices and HMRC records expect. Both 24-hour (14:30) and 12-hour (2:30 PM) inputs are accepted, with strict validation (minutes 00–59) so '9:75' fails loudly instead of silently corrupting a rota.

Use it for shifts, sleep, study blocks, parking, cooking, and billing. Pair it with the Date Difference calculator when spans cross midnight into multiple days.

Updated 2026-09-01 · 6-min read · Formula + steps included

● Time workstation

Time & Date →

Time formulas

duration = (end − start + 1440) mod 1440 • decimal = minutes ÷ 60 • newTime = (start + add) mod 1440

Convert HH:MM to minutes (h×60+m, with AM/PM mapped to 0–23). If end < start and overnight is on, add a full day (1,440 min) before subtracting. Decimal hours divide by 60. Adding a duration wraps modulo one day so 23:30 + 90 min = 01:00 next day.

start / end: Times as HH:MM, optional AM/PM. 00:00 is midnight start, 12 PM is noon.
1440: Minutes per day (24 × 60). The wrap constant for overnight shifts.
decimal: Payroll hours, e.g. 8h 25m = 8.42h (25 ÷ 60 = 0.4167).

Worked example: night shift 22:15 → 06:40

A nurse clocks 22:15 to 06:40. Payroll needs hours-and-minutes and decimals:

To minutes: 22×60+15 = 1,335; 6×60+40 = 400.
End < start so add a day: 400 + 1,440 = 1,840.
Subtract: 1,840 − 1,335 = 505 minutes.
Split: 505 ÷ 60 = 8h remainder 25m → 8h 25m.
Decimal: 505 ÷ 60 = 8.4167 → 8.42h for the timesheet.

Result: 8h 25m — 505 minutes — 8.42 decimal hours.

How to use this time calculator

Two modes, one input style.

Step 1: Enter start and end

Type 09:30, 9:30 PM or 21:30. For shifts ending next morning, keep overnight on.

Step 2: Read duration three ways

Hours-and-minutes for humans, total minutes for maths, decimals for payroll.

Step 3: Add durations

Enter a start plus hours/minutes to add (use negatives to subtract) to find end times for rotas and recipes.

Step 4: Reset between calculations

Clear errors like 'minutes must be 00–59' and re-run without reloading.

Use cases

Where minute-exact time matters:

Shifts & payroll

8h 25m × £14.50 = 8.42 × 14.50 ≈ £122.09. Decimal conversion removes the classic 8.25-vs-8.42 underpayment.

Sleep tracking

23:10 → 06:50 = 7h 40m (7.67h). Track weekly totals against the 7–9h adult guideline.

Freelance billing

Three blocks 1h20 + 2h05 + 0h45 = 4h10 = 4.17h × rate. Itemise decimals; clients audit them.

Study & Pomodoro

4 × 25m + breaks = plan end times: 09:00 + 1h55 = 10:55. Add-duration mode does this instantly.

Parking & penalties

'2 hours from 14:37' ends 16:37. Knowing the wrap prevents £65 tickets.

Pro tips

Rota-manager habits:

Subtract unpaid breaks before decimals: 8h25 − 0h30 = 7h55 = 7.92h, not 8.42h.
Round payroll per policy (nearest 6 min = 0.10h) — and state it on the sheet.
For multi-day spans, use Date Difference for days + this tool for the leftover hours.
Prefer 24h notation in shared rotas; AM/PM causes the 12 AM/PM mix-up.
Keep a minutes column in spreadsheets (=H*60+M) — sums never drift.

Common mistakes

Why timesheets go wrong:

Writing 8h25 as 8.25h

25 minutes is 0.42h, not 0.25h. The 0.17h gap underpays ~£2.50 per shift at £15/h.

Forgetting overnight wrap

22:00 → 06:00 is 8h, not −16h. Leave overnight on for night work.

12 AM/PM confusion

12 AM is midnight (00:00); 12 PM is noon. When unsure, use 00:00/12:00 24h form.

Invalid minutes

'14:75' is not a time. Minutes cap at 59 — the tool rejects these loudly by design.

FAQs

Frequently asked questions

Subtract start from end in minutes, adding 1,440 if the end is next day. Example: 22:15→06:40 = 505 min = 8h 25m = 8.42h. The tool does this automatically.