How do I calculate hours between two times?

Subtract the start time from the end time in minutes, then divide by 60. For example, from 9:15 AM to 4:45 PM = 450 minutes = 7.5 hours. If the end time is on a different date, include the date difference.

What is decimal time?

Decimal time expresses time in base-10 fractions rather than the base-60 system of hours:minutes:seconds. In a payroll context, "decimal hours" means hours expressed as a decimal (e.g., 7.75 hours instead of 7 hours 45 minutes).

How does Daylight Saving affect shift length?

On spring-forward night, a shift spanning 2:00 AM loses one hour (the clocks jump from 2:00 to 3:00). On fall-back night, a shift spanning 2:00 AM gains one hour (2:00 AM occurs twice). Accurate payroll must account for this.

Unix time (POSIX time) is the number of seconds elapsed since January 1, 1970 at 00:00:00 UTC, not counting leap seconds. It is the universal reference for time arithmetic in computing.

How many seconds are in a day?

86,400 seconds (24 hours × 60 minutes × 60 seconds = 86,400). Leap seconds occasionally add one extra second to a UTC day, but these are rare and not reflected in Unix time.

What is the difference between duration and interval?

A duration is an amount of elapsed time (e.g., 3 hours 30 minutes). An interval is a specific span of time defined by a start and end timestamp (e.g., from 9:00 AM on June 1 to 12:30 PM on June 1).

How do I add time durations together?

Add seconds separately, then add minutes (plus any carryover from seconds), then add hours (plus carryover from minutes). For example: 2h 45m + 1h 30m = 3h 75m = 4h 15m after carrying 60 minutes as one hour.

What is the maximum duration this calculator can handle?

This calculator handles any two valid calendar dates (including years far in the past or future) since it operates on Unix timestamps, which can represent dates from roughly 271 million BCE to 275 million CE.

How do I calculate how long I slept?

Enter your bedtime as the start time and wake time as the end time. If you went to bed before midnight and woke after, make sure the dates are set correctly (bedtime date = yesterday, wake time date = today).

What is a work week in hours?

A standard work week in many countries is 40 hours (5 days × 8 hours). Full-time employees in the EU are limited to 48 hours per week (including overtime) under the Working Time Directive.

How do I calculate billable hours accurately?

Track start and end times for each task to the nearest minute. Convert total minutes to decimal hours. Apply your hourly rate to the decimal hours total. Round consistently per your client agreement (nearest 15 minutes, nearest 6 minutes, etc.).

How are overtime hours calculated?

In the US, overtime is typically any hours worked beyond 40 in a week, paid at 1.5× the regular hourly rate. Some states require daily overtime (any hours beyond 8 in a single day). This duration calculator helps verify daily and weekly totals.

utility calculator

Time Duration & Elapsed Hour Solver

Calculate the exact duration between two timestamps in days, hours, minutes, and seconds, with a visual timeline bar and decimal hours output.

Formula Verified by Dr. Arthur Pendelton, PhD

Inputs

Start Timepoint

Start Date

Start Time

End Timepoint

End Date

End Time

Results

Duration Output

0 days, 8 hours, 0 minutes, 0 seconds

Decimal Hours

8.0000 hours

Total Minutes480 minutes

Total Seconds28800 seconds

Formula

Time Duration Conversion formulas

Elapsed Milliseconds = End Epoch - Start Epoch
Decimal Hours = Milliseconds / 3,600,000
Days = ⌊ Hours / 24 ⌋

Converts both timestamps into Unix millisecond timestamps, subtracts them to obtain the absolute duration, and divides sequentially to extract calendar units.

Step by step

How the calculation works

1Enter the start date and starting time.
2Enter the end date and ending time.
3The duration computes instantly in real-time.
4Review the decimal hours and detailed breakdowns in the result cards.

Example

Example Duration Calculation

From June 30 at 9:00 AM to June 30 at 5:30 PM is 8 hours and 30 minutes, which converts to 8.5000 decimal hours.

Related guides

Learn more about this calculation

Guide

Time Calculation Guide: Adding, Subtracting, and Converting Durations Correctly

Learn how to add and subtract time durations, convert total minutes into hours and decimal hours, and understand what the current DTC time calculator does well and where you should switch to hours or date-based tools.

Site Guide

How to Use Do The Calculation Calculators: A Practical Step-by-Step Guide

Learn the fastest reliable workflow for using Do The Calculation calculators, reading results, checking formulas, and using save, print, share, and export actions correctly.

utility calculator

Time Duration & Elapsed Hour Solver

Calculate the exact duration between two timestamps in days, hours, minutes, and seconds, with a visual timeline bar and decimal hours output.

Formula Verified by Dr. Arthur Pendelton, PhD

Inputs

Start Timepoint

Start Date

Start Time

End Timepoint

End Date

End Time

Results

Duration Output

0 days, 8 hours, 0 minutes, 0 seconds

Decimal Hours

8.0000 hours

Total Minutes480 minutes

Total Seconds28800 seconds

Summary

Key output metrics

Elapsed Decimal Hours

8.0000 hrs

Total decimal duration.

Calculated Breakdown

0d 8h 0m

Days, hours, and minutes split.

Input Timeline Status

Positive Range

End time compared to start time.

D3 visualization

Duration Units Breakdown

Compare the duration magnitude across days, hours, and minutes.

Formula

Time Duration Conversion formulas

Elapsed Milliseconds = End Epoch - Start Epoch
Decimal Hours = Milliseconds / 3,600,000
Days = ⌊ Hours / 24 ⌋

Converts both timestamps into Unix millisecond timestamps, subtracts them to obtain the absolute duration, and divides sequentially to extract calendar units.

Step by step

How the calculation works

1Enter the start date and starting time.
2Enter the end date and ending time.
3The duration computes instantly in real-time.
4Review the decimal hours and detailed breakdowns in the result cards.

Example

Example Duration Calculation

From June 30 at 9:00 AM to June 30 at 5:30 PM is 8 hours and 30 minutes, which converts to 8.5000 decimal hours.

Related guides

Learn more about this calculation

Guide

Time Calculation Guide: Adding, Subtracting, and Converting Durations Correctly

Site Guide

How to Use Do The Calculation Calculators: A Practical Step-by-Step Guide

Learn the fastest reliable workflow for using Do The Calculation calculators, reading results, checking formulas, and using save, print, share, and export actions correctly.