How is duration calculated between two dates?

The calculator computes the exact milliseconds between your start and end date/time, then breaks it down into years, months, days, hours, minutes, and seconds. It accounts for varying month lengths, leap years, and exact time differences.

Can I calculate working days only?

Yes! Toggle 'Include Weekends' off to exclude Saturdays and Sundays from the calculation. You can also customize working hours per day to get accurate working time calculations.

What's the difference between 'Total Days' and the breakdown?

'Total Days' shows the absolute number of days between dates (e.g., 45.7 days). The breakdown shows years/months/days format (e.g., '1 month, 15 days'). Both are accurate but represent the duration differently.

How do I calculate hours between two times?

Enter the start time and end time on the same date. The calculator returns the total hours and minutes between them, plus the result in decimal hours (useful for timesheets) and ISO 8601 duration format (useful for APIs and code).

Does the duration calculator handle Daylight Saving Time?

Yes. If your start and end span a DST transition, the calculator uses the correct local-to-UTC mapping for each date. So a 24-hour calendar window across a 'spring forward' day correctly resolves to 23 hours of elapsed time, while a 'fall back' day resolves to 25 hours.

What is ISO 8601 duration format?

ISO 8601 represents durations as strings like P1Y2M10DT5H30M (1 year, 2 months, 10 days, 5 hours, 30 minutes). It is the standard format used by APIs, databases, and programming languages worldwide. The calculator outputs this format alongside the human-readable breakdown.

Can I calculate duration in weeks?

Yes. The result panel shows the duration in weeks alongside days, hours, and other units. For example, 30 days displays as 4 weeks 2 days. The decimal-weeks value (e.g., 4.29 weeks) is also useful for project tracking.

How is this different from the Business Days Calculator?

Duration Calculator gives you the total elapsed time including weekends and holidays. Business Days Calculator excludes weekends and (optionally) public holidays so you only count working days. Use Duration for elapsed time, Business Days for actual work time.

Duration Calculator

Calculate precise time differences between any two dates. Get results in years, months, days, hours, minutes, and seconds with support for business days and working hours.

Date & Time Range

Start Date & Time

End Date & Time

Quick Examples

Duration Result

1 days, 0 hours, 0 minutes, 0 seconds

Exact Duration From

May 11, 2026, 7:53 PM → May 12, 2026, 7:53 PM

Detailed Breakdown

Total Days

Total Hours

1,440

Total Minutes

86,400

Total Seconds

How to Calculate Time Duration

Easily find the exact time between any two dates and times, with a detailed breakdown into days, hours, and minutes.

1. Set Start Point

Choose your beginning date and time. Use the "Now" button for a quick shortcut.

2. Set End Point

Select your target date and time. The duration calculates automatically as you type.

3. Analyze Results

See the result in multiple formats including ISO 8601 and total elapsed seconds.

Precise Time Measurements

Whether you're measuring project duration, tracking billable hours, or calculating the time between historical events, our tool provides the highest level of accuracy.

ISO 8601 Format

Millisecond Accuracy

More Useful Tools

Business Days Calc Add/Subtract Time Age Calculator Unix Epoch Converter World Clock

Frequently Asked Questions

Why Use Our Duration Calculator?

Instant Results

Real-time calculations as you select dates and times.

Multiple Formats

See results in years, months, days, hours, minutes, and seconds.

Business Days

Option to exclude weekends from your calculations.

Quick Presets

Common duration calculations with one click.

Hours Calculator — Time & Duration Calculator

Our time and duration calculator computes the exact difference between any two dates and times — displayed in days, hours, minutes, and seconds. Use it as an hours calculator to track working hours, measure event durations, or calculate elapsed time for billing and timesheets.

Enter a start and end timestamp and the time difference calculator instantly returns the result in multiple formats: total hours, ISO 8601 duration, and a human-readable breakdown. Quick presets like "last 24 hours" or "last 7 days" let you get answers with a single click. The calculator is timezone-aware, so cross-timezone durations are always accurate.

Whether you need an hour to hour calculator for payroll, measuring how long a process took, or planning time-sensitive workflows, this tool handles it all. Pair it with the business days calculator to exclude weekends, or use the epoch converter to work with Unix timestamps.

Common Duration Calculations

These are the most-asked duration questions and how the calculator handles each one.

Hours Between 9 AM and 5 PM

8 hours. The classic 'work day' baseline. The calculator returns 8h 0m, ISO 8601 PT8H, and 0.33 days.

Days from Birth to Today

Use Today as end date and your birth date as start. For someone born exactly 30 years ago, expect ~10,950 days (30 × 365.25). The Age Calculator gives the same result with additional zodiac and milestone data.

Weeks Until a Project Deadline

Set Today as start, deadline as end. The calculator shows weeks plus the remainder in days — for example, '6 weeks 3 days' for a 45-day deadline.

Hours Between Two Timezones

Enter both times in their own timezone using the timezone selector. The calculator converts both to UTC internally and reports the true elapsed duration, not the clock-time difference.

Duration of an Event Across DST Transition

An overnight event from 11 PM to 1 AM that crosses 'spring forward' at 2 AM is 1 hour, not 2 hours. The calculator correctly handles this by computing real elapsed time.

Standard Duration Reference

Quick reference for unit conversions when working with durations.

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 · 10,080 minutes
1 month (avg)	30.44 days · 730 hours (varies by month)
1 year (Gregorian)	365.2425 days · 8,765.82 hours · 31,556,952 seconds
1 leap year	366 days · 8,784 hours · 31,622,400 seconds
1 decade	3,652 days (with 2-3 leap years) · ~87,672 hours
1 century	36,524 or 36,525 days · ~876,576 hours