Hours Calculator
Add up hours and minutes for any number of work shifts or time entries. Calculate total hours worked, convert to decimal for payroll, and verify your timesheet automatically.
Enter your values above to see the results.
Tips & Notes
- ✓Always convert time to decimal hours before multiplying by an hourly rate. 6h 45m is 6.75 decimal hours, not 6.45. Multiplying 6.45 by your rate produces an incorrect pay calculation.
- ✓For weekly totals, add up each day first, then sum the daily totals — do not try to add all start and end times directly. Adding daily subtotals reduces the chance of minute-carry errors.
- ✓If your employer rounds to the nearest quarter-hour, determine the rounding threshold: some round at 7 minutes (so 7:07 rounds to 7:00), others at 8 minutes. Knowing the rule lets you verify your own timesheet.
- ✓Track break time separately and subtract explicitly. A 9:00–5:30 shift with a 45-minute lunch = 8.5 hours − 0.75 hours = 7.75 hours, not 8.5 hours of billable time.
- ✓For project billing, convert all time entries to decimal hours before summing, then multiply by the billing rate. Summing HH:MM entries and then converting introduces rounding errors that affect invoice accuracy.
Common Mistakes
- ✗Treating 7:45 as 7.45 decimal hours — minutes are base-60, not base-100. 45 minutes = 0.75 hours, so 7:45 = 7.75 decimal hours. The error seems small per hour but multiplies significantly across a payroll.
- ✗Adding minutes past 60 without converting — 2h 45m + 1h 30m = 3h 75m, which should be 4h 15m. Always check if the minute total exceeds 59 and carry the overflow to hours.
- ✗Ignoring negative time when subtracting — if a session started at 11:30 PM and ended at 2:15 AM, the duration crosses midnight. Treat it as (24:00 − 11:30) + 2:15 = 14h 45m, not as a negative number.
- ✗Not accounting for unpaid breaks in total work hours — a timesheet showing 9 AM to 6 PM is 9 hours, but if 1 hour of lunch is unpaid, the billable or payable hours are 8.
- ✗Rounding each individual time entry before totaling — round only at the final step, not intermediate calculations. Rounding each daily entry and then summing produces a different result than summing exact times and rounding once.
Hours Calculator Overview
An hours calculator adds, subtracts, or totals time values expressed in hours and minutes — the essential tool for payroll processing, timesheet verification, project billing, and any situation where multiple time spans must be accurately summed. Unlike decimal arithmetic, time arithmetic uses a base-60 system where 60 minutes equals 1 hour, which makes mental calculation error-prone and spreadsheet formulas unexpectedly complex.
Time addition — the core operation:
Total Time = Sum of all hours + Sum of all minutes, then convert minutes ≥ 60 into hours
EX: 3h 45m + 2h 30m + 1h 50m → Hours: 3+2+1=6 | Minutes: 45+30+50=125 | 125 min = 2h 5m → Total: 8h 5mConverting between decimal hours and hours:minutes:
Decimal hours = hours + (minutes ÷ 60) | Minutes = decimal fraction × 60
EX: 7h 45m = 7 + (45÷60) = 7 + 0.75 = 7.75 decimal hours → 7.75 × hourly rate = correct payCommon time fraction conversions — memorize for fast mental calculation:
| Minutes | Decimal Hours | Common Context |
|---|---|---|
| 15 minutes | 0.25 hours | Quarter-hour billing |
| 20 minutes | 0.333 hours | Third-hour increments |
| 30 minutes | 0.50 hours | Half-hour shifts, lunch breaks |
| 45 minutes | 0.75 hours | Three-quarter hour |
| 90 minutes | 1.50 hours | Extended sessions, 1.5-hour classes |
| 120 minutes | 2.00 hours | 2-hour blocks |
| Schedule Type | Daily Hours | Days/Week | Weekly Total | Annual Hours |
|---|---|---|---|---|
| Standard full-time (US) | 8h 00m | 5 | 40h 00m | 2,080 hrs |
| Part-time (half) | 4h 00m | 5 | 20h 00m | 1,040 hrs |
| 4-day workweek | 10h 00m | 4 | 40h 00m | 2,080 hrs |
| Retail / shift (typical) | 7h 30m | 5 | 37h 30m | 1,950 hrs |
| Overtime week | 8h 00m | 5 | 40h + OT | Varies |
| Annual leave days (US avg) | 8h 00m | — | — | −120 hrs (15 days) |
Frequently Asked Questions
Add hours and minutes separately. Then check if total minutes are 60 or more: if so, subtract 60 from the minutes and add 1 to the hours. Example: 3h 40m + 2h 35m → hours: 5, minutes: 75 → 75 ≥ 60 → hours: 6, minutes: 15 → total: 6h 15m. For multiple entries: add all minutes, divide by 60 to get additional hours (take the integer part), and the remainder is the final minutes.
Divide the minutes by 60 and add to the hours. 7h 45m = 7 + (45÷60) = 7 + 0.75 = 7.75 decimal hours. 8h 20m = 8 + (20÷60) = 8 + 0.333 = 8.333 decimal hours. To convert back: take the decimal part and multiply by 60 to get minutes. 8.333 hours = 8 hours + (0.333 × 60) = 8h 20m.
A standard full-time US employee works 40 hours per week × 52 weeks = 2,080 hours per year. This is the baseline for annual salary calculations: a $50,000 salary equals $50,000 ÷ 2,080 = $24.04 per hour. If the employer provides 10 paid holidays (80 hours), actual working hours are 2,080 − 80 = 2,000. For hourly workers, total annual hours vary based on actual weeks worked and any leave taken.
If a shift spans midnight, calculate in two segments: hours from start to midnight (00:00) and hours from midnight to end. Example: 10:30 PM to 6:45 AM → segment 1: midnight − 10:30 PM = 1h 30m → segment 2: 6h 45m → total: 1h 30m + 6h 45m = 8h 15m. Alternatively: convert both times to 24-hour format (22:30 to 30:45 treating next-day as hour 24+) and subtract.
Clock hours use HH:MM format (base-60 minutes). Decimal hours express the same duration as a decimal number (base-10). Payroll systems multiply hourly rates by decimal hours. The key conversion: minutes ÷ 60 = decimal fraction. A common payroll error: 8:30 is entered as 8.30 decimal hours (treating minutes as hundredths), but 30 minutes = 0.50 hours, making the correct value 8.50. The error of 0.20 decimal hours × $20/hour = $4 per shift, $1,040 per year for a daily worker.
Enter each shift as start time and end time, calculate the duration for each, sum all durations, then subtract any unpaid break time. For a biweekly pay period with 10 shifts: calculate each shift duration, sum to get gross hours, subtract breaks (typically 30 min per shift = 5 hours), and the result is net payable hours. Convert to decimal before multiplying by hourly rate.