Time Duration Calculator

Calculate elapsed time between dates and times, subtract breaks, handle overnight shifts, audit rounding, and total multiple work or project intervals.

Start and end time

Start date

Start time

End date

End time

Automatically treat an earlier end time as the next day

Break deduction

min

Rounding audit

Hourly rate (optional)

Currency

Duration results

Choose start and end times, then calculate.

Net duration—

Decimal hours—

Total minutes—

Total seconds—

Rounded duration—

Gross elapsed—

Break deducted—

Rounding difference—

Start—

End—

Formula and overnight handling

Elapsed time: end date/time − start date/time.

Net duration: elapsed time − break duration.

If an end time is earlier on the same date and overnight handling is enabled, 24 hours are added before subtracting breaks.

Multiple-interval workspaceTotal work shifts, study sessions, exercise periods, or project blocks

LabelStartEndBreakDuration

Add one or more time intervals.

Add or subtract durationsCalculate with values such as 1:30, 45m, or 2h 15m

First duration

Operation

Second duration

Enter two durations.

Excel & Google Sheets formulasStart time, end time, and break calculations

Start cell

End cell

Break minutes cell

People used this calculator

Your current platform: —

Method usedSubtract start date/time from end date/time, then deduct breaks before deriving outputs

Outputs supportedNet and gross duration, decimal hours, minutes, seconds, overnight shifts, rounding audit, pay, and interval totals

Last reviewedJuly 18, 2026 • CalculatorGeek Algorithmic Team

Important noteVerify time zones, daylight-saving transitions, break policy, and jurisdiction-specific payroll rules

Direct answer: Time duration is the end date and time minus the start date and time, less any break. For example, 9:00 AM to 5:00 PM is 8 hours; after a 30-minute break, the net duration is 7 hours 30 minutes or 7.5 decimal hours.

What the Time Duration Calculator Does

This calculator finds elapsed time within one day or across dates. It can automatically treat an earlier end time as the next day, deduct a break, show decimal hours, total minutes and seconds, audit interval rounding, estimate pay, total several intervals, and add or subtract duration values.

Scenario	Gross duration	Net duration
9:00 AM–5:00 PM, 30-minute break	8:00	7:30
10:00 PM–6:00 AM	8:00	8:00 before breaks
July 18 3:15 PM–July 19 9:45 AM	18:30	18:30 before breaks

Formula and Methodology

gross elapsed = end date/time − start date/time
net duration = gross elapsed − break duration
decimal hours = net seconds ÷ 3,600
total minutes = net seconds ÷ 60

The unit relationships use 60 seconds per minute and 3,600 seconds per hour, consistent with the NIST Guide to the SI. The calculator converts both date-time values to one timeline, subtracts them, deducts the break, and then derives each output from the resulting duration.

The unrounded net duration is calculated first. Any selected 1-, 5-, 6-, or 15-minute audit is compared with the original value so the difference remains visible.

How to Use the Calculator

Enter the start date and time and the end date and time.
If the shift crosses midnight and the end date is not entered separately, enable the next-day option.
Enter the break deduction in minutes.
Choose a rounding interval only when you need to audit a defined reporting or payroll rule.
Optionally add an hourly rate, then calculate and copy the required outputs.

Worked Duration Examples

Workday with a Break

Start 9:00 AM, end 5:00 PM: gross elapsed = 8 hours. Subtract a 30-minute break: net duration = 7 hours 30 minutes = 7.50 hours = 450 minutes.

Overnight Shift

Start 10:00 PM, end 6:00 AM the next day: 8 hours. Subtract a 45-minute break and the net duration becomes 7 hours 15 minutes = 7.25 hours.

Multi-Day Project Window

From July 18 at 3:15 PM to July 19 at 9:45 AM is 18 hours 30 minutes = 18.50 hours = 1,110 minutes.

Borrowing Minutes in Manual Time Subtraction

When the ending minutes are smaller than the starting minutes, borrow one hour as 60 minutes. For 13:20 minus 9:45, rewrite 13:20 as 12:80, then subtract: 12:80 − 9:45 = 3 hours 35 minutes. The calculator performs this normalization automatically.

Breaks, Overnight Shifts, and Multiple Intervals

A break is deducted after gross elapsed time is established. Overnight handling should represent the intended next day, not a negative duration. For split shifts or project sessions, calculate each interval consistently and use the multiple-interval total instead of manually adding rounded results.

Decimal Hours and Payroll Rounding

Use decimal hours for multiplication, billing, and payroll calculations; use HH:MM for human-readable duration. Keep display rounding separate from a payroll interval rule. The U.S. Department of Labor FLSA Hours Worked Advisor says accepted time-clock rounding practices must not result, over time, in employees losing compensable time. Other jurisdictions may differ.

Common Mistakes

Forgetting to advance the end date for an overnight shift.
Subtracting the break twice or entering paid break time as unpaid.
Reading 7.30 decimal hours as 7 hours 30 minutes; 7.30 hours is 7 hours 18 minutes.
Adding separately rounded intervals instead of totaling exact durations first.
Ignoring time-zone or daylight-saving differences when start and end are not in the same local time context.

Practical Uses

Use the calculator for work shifts, payroll audits, freelance billing, study sessions, workouts, events, travel segments, machine runtime, service appointments, and project tracking. Keep the original start/end records when the result will support pay, billing, attendance, or compliance decisions.

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Frequently Asked Questions

How do I calculate the duration between two times?

Subtract the start date and time from the end date and then deduct any break. The calculator performs the borrowing and overnight handling automatically.

How many hours are between 9:00 AM and 5:00 PM?

The gross duration is 8 hours. With a 30-minute unpaid break, the net duration is 7 hours 30 minutes, or 7.5 decimal hours.

How do I calculate an overnight shift?

Use the correct start and end dates, or enable the next-day option when the end time is earlier than the start time. For 10:00 PM to 6:00 AM, the duration is 8 hours before breaks.

How do I subtract a break from elapsed time?

Calculate the gross elapsed duration and subtract the break minutes. An 8-hour shift minus a 30-minute break equals 7 hours 30 minutes.

What is the difference between elapsed time and decimal hours?

Elapsed time is normally written as hours, minutes, and seconds. Decimal hours express the same duration as one base-10 number for calculations.

Can I calculate duration across different dates?

Yes. Enter both dates and times to calculate multi-day elapsed duration.

Can I total multiple time intervals?

Yes. Use the multiple-interval feature to add work shifts, study sessions, workouts, or project blocks.

Can I subtract one duration from another?

Yes. Use the time-math feature and choose subtract, then enter values such as 1:30, 45m, or 2h 15m.

Does the calculator handle daylight saving time or time zones?

The tool calculates from the dates and local times entered. For different time zones or daylight-saving transitions, verify the intended timezone and workplace rule before relying on the result.

How does rounding affect a time duration?

Display rounding and payroll interval rounding can change the reported value. Review the rounding difference and keep the unrounded duration for an audit trail.

References

The methodology and guidance on this page use the following authoritative or operational sources:

National Institute of Standards and Technology. NIST Guide to the SI, Chapter 5: Units Outside the SI.
U.S. Department of Labor. FLSA Hours Worked Advisor: Recording Hours Worked (U.S. federal example; rules vary).