Time Add/Subtract Calculator

Time Add/Subtract

Add or subtract hours and minutes from a base time.

Operation
Time format
Base time
h:mm

Results

Time Result

Result time
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Day shift
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Related Calculators

Time Duration Calculator

Hours and minutes between two times (supports overnight shifts)

Time Zone Converter

Convert time between zones (DST-safe, shows date shift)

Quick Jump:How It WorksUse CasesExamplesDuration FormatFAQs

How this calculator works

The calculator converts your base time into minutes since midnight, adds (or subtracts) your duration in minutes, then converts the result back into a clock time. If the result crosses midnight, you'll see a day shift such as +1 day or -1 day.

  • Current time auto-filled - The calculator reads your device's current time and day, so you can instantly calculate "what time will it be in X hours?".
  • Flexible duration - Enter any number of hours (even 2000+). Type digits and the field treats them as hours (e.g., "50" becomes 50:00).
  • 12h / 24h support - Switch between AM/PM format and military time.

Common use cases

Flight arrivals

Departure 11:00 PM + 14h flight = 1:00 PM (+1 day). Plan your pickup accordingly.

Work shifts

Start at 10:00 PM, work 8 hours = end at 6:00 AM next day.

Cooking times

Put the roast in at 2:30 PM, cook for 3h 45m = done at 6:15 PM.

Meeting planning

Meeting at 4:00 PM lasts 1h 30m = ends at 5:30 PM.

Examples

Same day

9:00 AM + 2:15 = 11:15 AM (same day)

Crossing midnight

11:30 PM + 2:00 = 1:30 AM (+1 day)

Subtract crossing midnight

1:00 AM - 3:00 = 10:00 PM (-1 day)

With day of week

Monday 11:30 PM + 2:00 = Tuesday 1:30 AM

Duration input format

The duration field accepts flexible formats. You can enter any number of hours (no limit):

InputInterpreted as
2:302 hours 30 minutes
5050 hours 0 minutes (50:00)
2000:302000 hours 30 minutes
0:4545 minutes

Frequently Asked Questions

What does "day shift" mean?▼
Day shift tells you how many days the result moved relative to the original time. For example, 23:30 + 2h = 01:30 (+1 day). A negative shift like -1 day means you crossed midnight backwards.
Why is the base time auto-filled?▼
The calculator auto-detects your current time and day from your device. This makes it easy to calculate 'what time will it be in X hours?' without manual entry. You can change it if calculating for a different time.
How do I enter the duration?▼
Enter duration as H:MM (like 2:30 for 2 hours 30 minutes). You can also enter just a number (like 50) which becomes 50:00 (50 hours). Large values like 2000:30 are supported.
Does this use time zones or DST rules?▼
No. This is a clock-time calculation (hours/minutes) only. For time zones and DST-safe conversions, use the Time Zone Converter.
Can I subtract a duration?▼
Yes. Choose "Subtract" and enter the duration you want to subtract. The calculator will show if the result falls on a previous day (-1 day).
What happens if I add more than 24 hours?▼
The calculator handles any duration. Adding 50 hours would show +2 days shift. The resulting time wraps around the 24-hour clock appropriately.
Can I use this for flight arrival times?▼
Yes! Enter your departure time, add the flight duration, and see the arrival time. If the flight crosses midnight, you'll see the day shift (e.g., +1 day means you arrive the next day).
How do I calculate backwards from an arrival time?▼
Use Subtract mode. Enter your target arrival time as the base, then subtract the duration to find when you need to start or depart.