Time Calculator
Add, subtract, multiply, divide time. Find duration between dates. Convert time zones, calculate business days, run a stopwatch or countdown timer. 20 languages.
Add time values together. Add more rows as needed.
📋 Table of contents
How to add and subtract time
Time arithmetic uses base-60 for seconds and minutes (carry at 60), and base-24 for hours (carry at 24). Use the Add tab above to sum multiple durations, or Subtract to find the difference.
Duration between two dates
The Date Diff mode gives the full breakdown in years, months, weeks, days. The DateTime Diff mode adds hours, minutes, and seconds precision — useful for exact elapsed time calculations.
| Period | Days | Hours | Minutes | Seconds |
|---|---|---|---|---|
| 1 Week | 7 | 168 | 10,080 | 604,800 |
| 1 Month (avg) | 30.44 | 730.5 | 43,829 | 2,629,746 |
| 1 Year (avg) | 365.25 | 8,766 | 525,960 | 31,557,600 |
| 1 Decade | 3,652.5 | 87,660 | 5,259,600 | 315,576,000 |
Add or subtract from a date
The Add to Date mode answers questions like: What date is 90 days from today? What day was 6 months ago? When does a 30/60/90-day period expire?
Business days calculator
Business days are weekdays Monday–Friday, excluding weekends. Enter any two dates and the number of public holidays in range to get an accurate working-day count.
- Contract deadlines — "30 business days from signing"
- Shipping estimates — "5–7 business days"
- Legal notice periods and court filing windows
- Project sprint planning — days in a sprint
Time zone converter
The Time Zone mode converts any date and time across 28 major world time zones at once. The World Clock shows live current times in 8 major cities, updating every second.
| Zone | UTC Offset | Major Cities |
|---|---|---|
| UTC | +0:00 | London (winter), Reykjavik |
| EST | −5:00 | New York, Toronto |
| PST | −8:00 | Los Angeles, Vancouver |
| IST | +5:30 | Mumbai, Delhi |
| CST | +8:00 | Beijing, Shanghai |
| JST | +9:00 | Tokyo, Seoul |
| AEST | +10:00 | Sydney, Melbourne |
Time unit reference
| Unit | Seconds | Minutes | Hours |
|---|---|---|---|
| 1 Minute | 60 | 1 | 0.0167 |
| 1 Hour | 3,600 | 60 | 1 |
| 1 Day | 86,400 | 1,440 | 24 |
| 1 Week | 604,800 | 10,080 | 168 |
| 1 Month (avg) | 2,629,746 | 43,829 | 730.5 |
| 1 Year (avg) | 31,557,600 | 525,960 | 8,766 |