How to convert hours to seconds
Every hour is 3,600 seconds, so the conversion is a single multiplication:
Worked example: 25 h → 25 × 3600 = 90,000 s.
Quick mental estimate: Multiply by 3600: 25 × 3600 ≈ 90,000 s (exact: 90,000).
Hours to seconds conversion table
| Hours (h) | Seconds (s) |
|---|---|
| 1 h | 3,600 s |
| 2 h | 7,200 s |
| 3 h | 10,800 s |
| 5 h | 18,000 s |
| 10 h | 36,000 s |
| 15 h | 54,000 s |
| 20 h | 72,000 s |
| 25 h | 90,000 s |
| 50 h | 180,000 s |
| 75 h | 270,000 s |
| 100 h | 360,000 s |
| 200 h | 720,000 s |
| 250 h | 900,000 s |
| 500 h | 1,800,000 s |
| 1,000 h | 3,600,000 s |
Values rounded to four decimals. For a value that is not in the table, use the converter above — it accepts decimals and negative numbers.
When you need this conversion
- Project planning and deadlines, where a duration given in one unit has to be turned into the granularity your schedule uses.
- Billing and payroll: hours worked converted into days, or a rate quoted per unit of time.
- Cooking, exercise, media durations and any timer set from a figure written in another unit.
Getting it right
The arithmetic is a single multiplication, so mistakes almost never come from the calculation itself — they come from the value that goes into it. Check that the figure you are converting really is in hours and not in a neighbouring unit, and that you have not already converted it once.
Sanity-check the direction of the result before you use it. One hour is 3,600 seconds, so converting hours to seconds should make the number larger. If it moved the other way, the conversion was applied backwards — the reverse converter is one click away.
About the units
Hour (h)
The hour is 60 minutes, or 3 600 seconds — one 24th of a day.
Second (s)
The second is the SI base unit of time, defined by the vibration of a caesium-133 atom. Timers, sports results and physics work in seconds.
Frequently asked questions
How many seconds are in 1 hour?
1 hour equals 3,600 seconds. To convert any value, multiply the number of hours by 3600.
How do I convert hours to seconds in my head?
Multiply by 3600: 25 × 3600 ≈ 90,000 s (exact: 90,000).
Is the h to s conversion exact?
The factor is a standard rounded value; for most purposes four significant figures are more than enough.
How do I convert hours to seconds in Excel or Google Sheets?
Put the value in A1 and use =A1*3600. Multiplying by the factor works in every spreadsheet, in any programming language, and on a basic calculator.
How many decimal places should I keep?
One hour is 3,600 seconds, so any imprecision in your input is magnified: rounding the input by 0.1 h shifts the result by 360 s. Enter the most precise value you have and round only the final answer.