Add, subtract, and calculate time differences — hours, minutes, seconds
| Unit | Equivalent |
|---|---|
| 1 minute | 60 seconds |
| 1 hour | 60 minutes / 3,600 seconds |
| 1 day | 24 hours / 1,440 minutes / 86,400 seconds |
| 1 week | 7 days / 168 hours / 604,800 seconds |
| 1 month (avg) | 30.44 days / 730.5 hours |
| 1 year | 365.25 days / 8,766 hours / 31,557,600 seconds |
Enter hours, minutes, and seconds for each time entry. Use the + or − operator between entries. Click "Add another time" to chain multiple operations. The calculator handles carry-over automatically (e.g., 75 minutes becomes 1 hour 15 minutes).
Enter a start time and end time in 12-hour format (AM/PM). The calculator shows the elapsed time between the two. If the end time is earlier than the start time, it assumes the end is the next day.
Enter a value and select the source and target units. Supports hours, minutes, seconds, days, weeks, and milliseconds.
Adding time: Convert all values to the smallest unit (seconds), add them, then convert back. Example: 2h 30m + 1h 45m → 9000s + 6300s = 15300s = 4h 15m 0s.
Subtracting time: Same approach — convert to seconds, subtract, convert back. If the result is negative, it represents going backward in time.
Time difference: Convert both times to seconds since midnight. Subtract start from end. If negative, add 86400 (seconds in a day) for overnight spans.
Decimal to time: Whole number = hours. Multiply decimal × 60 = minutes. Multiply remaining decimal × 60 = seconds. Example: 2.75 hours = 2h 45m 0s.
| Scenario | Calculation | Result |
|---|---|---|
| 8-hour workday with 1h lunch | 9:00 AM to 5:00 PM − 1h | 7 hours |
| Half marathon pace (2h target, 13.1 mi) | 120 min ÷ 13.1 | 9:09 per mile |
| Flight: depart 3:45 PM, arrive 9:20 PM | 21:20 − 15:45 | 5h 35m |
| Recipe: 1h 45m + 30m prep | 1:45 + 0:30 | 2h 15m |
| Sleep: 11:30 PM to 7:00 AM | (7:00 + 24:00) − 23:30 | 7h 30m |
How do I calculate the time between two times?
Subtract the earlier time from the later time. Convert both to the same unit (e.g., minutes), subtract, then convert back. For example, from 9:30 AM to 2:15 PM: 14:15 − 9:30 = 4 hours 45 minutes. Use the "Time Difference" tab above for instant results.
How do I add hours and minutes together?
Add hours and minutes separately. If the minutes total 60 or more, convert every 60 minutes to 1 hour. For example: 2h 45m + 3h 30m = 5h 75m = 6h 15m.
How many minutes are in an hour?
There are 60 minutes in 1 hour. To convert hours to minutes, multiply by 60. To convert minutes to hours, divide by 60.
How do I calculate elapsed time?
Elapsed time is the difference between a start and end time. Subtract the start from the end. If crossing midnight, add 24 hours to the end time first.
How many seconds are in a day?
There are 86,400 seconds in a day (24 × 60 × 60). A week has 604,800 seconds. A non-leap year has 31,536,000 seconds.
How do I convert decimal hours to hours and minutes?
Take the whole number as hours, then multiply the decimal part by 60 for minutes. Example: 3.75 hours = 3 hours and 45 minutes (0.75 × 60 = 45).
What is military time?
Military time uses a 24-hour clock (0000–2359). AM stays the same (8:00 AM = 0800), PM adds 12 (3:00 PM = 1500). Midnight is 0000, noon is 1200.
How do I calculate work hours for a timesheet?
Subtract clock-in from clock-out, then subtract break time. Example: 8:30 AM to 5:15 PM with 1h lunch = 8h 45m − 1h = 7h 45m.
How do I calculate overtime hours for payroll?
In the US, overtime is any time worked over 40 hours in a workweek. Add up your daily work hours across all 5 days, then subtract 40. For example, if you worked 43.5 hours total, you have 3.5 overtime hours. Some states also require daily overtime for hours over 8 per day. Use the Add/Subtract tab above to total your weekly hours.
How do I convert hours and minutes to decimal for payroll?
Divide the minutes by 60 and add to the hours. For example: 7 hours 45 minutes = 7 + (45 ÷ 60) = 7.75 decimal hours. Multiply decimal hours by your hourly rate to get pay. Common conversions: 15 min = 0.25, 30 min = 0.50, 45 min = 0.75.
What is the time difference between time zones?
Time zone differences are expressed as UTC offsets. For example, New York is UTC−5 (EST) and London is UTC+0 (GMT), so the difference is 5 hours. To convert: add or subtract the hour difference. If it's 3:00 PM in New York, it's 8:00 PM in London. Use an epoch converter for precise UTC-based time conversions.
How do I calculate the duration between two dates and times?
For spans that cross multiple days, first calculate the full days between the dates, then add the time portion. For example, from Monday 9:00 AM to Wednesday 2:30 PM = 2 days + 5h 30m = 53h 30m total. For date-based calculations, try our Date Calculator.
This free online time calculator handles three types of time math: adding and subtracting durations, finding the difference between two clock times, and converting between time units. Here is how to get the most out of each mode.
Click one of the three tabs at the top of the calculator. Use Add / Subtract when you want to total up durations (e.g., how long did I work this week?). Use Time Difference when you have two clock times and need the gap between them (e.g., 9:15 AM to 4:45 PM). Use Convert to switch between hours, minutes, seconds, days, weeks, or milliseconds.
In Add/Subtract mode, fill in the hours, minutes, and seconds fields for each row. Click + Add another time to include more entries — useful for tracking multiple tasks or shifts. Select + to add or − to subtract each entry from the running total. The calculator automatically handles carry-overs (e.g., 75 minutes becomes 1 hour 15 minutes).
In Time Difference mode, enter a start time and end time using 12-hour format and select AM or PM. If the end time is before the start time (e.g., a night shift crossing midnight), the calculator adds 24 hours automatically to give the correct elapsed duration.
Hit the blue Calculate button. Results display in hours, minutes, and seconds, plus the total in seconds and decimal minutes for easy payroll or spreadsheet entry. All calculations happen instantly in your browser — no data is sent to a server.
Copy the decimal hours value directly into payroll software or a spreadsheet. If you need to work with dates as well as times (e.g., calculating how many days and hours between two timestamps), visit the Date Calculator. For Unix timestamp conversions, the Epoch Converter converts between human-readable times and Unix epoch values.
Accurate payroll starts with precise time tracking. To calculate work hours for a single shift: note your clock-in time and clock-out time, find the difference using the Time Difference tab, then subtract any unpaid break time using the Add/Subtract tab.
For a full workweek, add each day's net hours together. If you worked 7h 30m Monday, 8h 00m Tuesday, 7h 45m Wednesday, 8h 15m Thursday, and 6h 30m Friday, enter all five as separate rows in Add/Subtract mode to get your weekly total (37h 60m = 38h 00m). Then multiply the decimal equivalent by your hourly rate to compute gross pay.
The most common use case: you know a start time and end time and want the elapsed duration. Switch to the Time Difference tab, enter both times with AM/PM, and click Calculate Difference. The result appears in hours, minutes, and seconds.
Manual method when you need to show your work: convert both times to 24-hour format, express each as total minutes since midnight, subtract, then convert back. Example — 10:30 AM to 3:45 PM: 10:30 = 630 minutes; 15:45 = 945 minutes; 945 − 630 = 315 minutes = 5 hours 15 minutes.
Payroll software, spreadsheets, and billing systems often require decimal hours rather than hours:minutes format. The conversion is straightforward: decimal hours = hours + (minutes ÷ 60).
Quick reference: 6 min = 0.10 hrs · 12 min = 0.20 hrs · 15 min = 0.25 hrs · 18 min = 0.30 hrs · 24 min = 0.40 hrs · 30 min = 0.50 hrs · 36 min = 0.60 hrs · 45 min = 0.75 hrs · 48 min = 0.80 hrs · 54 min = 0.90 hrs.
To reverse it (decimal back to minutes): take the decimal part and multiply by 60. So 2.4 hours = 2 hours and (0.4 × 60) = 24 minutes.
Under US federal law (FLSA), overtime applies to hours worked beyond 40 in a workweek, paid at 1.5× the regular rate. To calculate: sum all weekly hours in decimal form, subtract 40, and the remainder is overtime. Example: 43.75 hours worked − 40 = 3.75 overtime hours.
California and some other states use daily overtime rules: over 8 hours in a day triggers 1.5×, and over 12 hours triggers 2×. Track each day's hours separately to catch daily overtime. The Date Calculator can help confirm which days fall within the same workweek when pay periods straddle month boundaries.
Time zones are defined as offsets from Coordinated Universal Time (UTC). The world is divided into 24 standard time zones, each roughly 15 degrees of longitude wide, though political boundaries mean many zones have unusual shapes. The offset ranges from UTC−12:00 (Baker Island) to UTC+14:00 (Line Islands).
UTC−8 (PST) — Los Angeles, Seattle, Vancouver · UTC−7 (MST) — Denver, Phoenix · UTC−6 (CST) — Chicago, Mexico City · UTC−5 (EST) — New York, Toronto, Miami · UTC+0 (GMT) — London (winter), Dublin, Reykjavik · UTC+1 (CET) — Paris, Berlin, Rome · UTC+5:30 (IST) — Mumbai, New Delhi · UTC+8 (CST) — Beijing, Singapore, Manila · UTC+9 (JST) — Tokyo, Seoul · UTC+10 (AEST) — Sydney, Melbourne.
Most of the US, Canada, and Europe observe Daylight Saving Time (DST), advancing clocks by one hour in spring and reverting in autumn. During DST, New York is UTC−4 (EDT) instead of UTC−5 (EST). Not all countries observe DST — Arizona, most of Africa, Japan, China, and India keep a fixed offset year-round. Always confirm whether DST is in effect when scheduling across time zones.
To convert a time from one zone to another: (1) convert the source time to UTC by applying the inverse of the source offset, (2) apply the target offset. Example — 3:00 PM EST (UTC−5) to Tokyo (UTC+9): 3:00 PM + 5h = 8:00 PM UTC; 8:00 PM + 9h = 5:00 AM next day JST. For precise Unix epoch conversions across time zones, use the Epoch Converter.