Convert days to seconds
Converting days to seconds is a common time task, whether you are checking a recipe, a spec sheet, a travel distance or a homework problem. Since 1 d equals 86,400 s, the math is a single multiplication — and this page does it for you instantly, with the formula, a table of common values and answers to the questions people ask most.
Exact factor
How to convert days to seconds
To convert days to seconds, multiply the number of days by 86,400. For example, 10 d × 86,400 = 864,000 s.
s = d × 86,400
- Write down the value in days you want to convert.
- Multiply it by 86,400 (the exact d→s factor).
- The result is your value in seconds. Check it below with the converter or the table.
Conversion table
Common values of days and their equivalents in seconds:
| d | s |
|---|---|
| 1 | 86,400 |
| 2 | 172,800 |
| 3 | 259,200 |
| 4 | 345,600 |
| 5 | 432,000 |
| 10 | 864,000 |
| 20 | 1,728,000 |
| 25 | 2,160,000 |
| 50 | 4,320,000 |
| 100 | 8,640,000 |
| 250 | 21,600,000 |
| 500 | 43,200,000 |
About these units
Day (d). A day equals 24 hours or 86,400 seconds, approximating one rotation of the Earth. Calendars, deadlines and project plans are built on days.
Second (s). The second is the SI base unit of time, defined by the cesium-133 atomic transition frequency of 9,192,631,770 hertz. It is the foundation of all time measurement.
Frequently asked questions
How do I convert days to seconds?
To convert days to seconds, multiply the number of days by 86,400. For example, 10 d × 86,400 = 864,000 s. Or skip the math: type the value into the converter at the top of this page and the result updates instantly.
How many seconds are in 1 day?
1 d = 86,400 s. That is the fixed relationship used by this converter and by international standards.
How many days are in 1 second?
1 s = 0.0000115741 d. If you are converting in the opposite direction, use our Second to Day converter for the dedicated table and FAQ.
Is the days to seconds conversion exact?
Yes. Both units are defined by international agreement, so the factor of 86,400 is exact. Displayed results are rounded to 6 significant digits only for readability.
What is day used for?
A day equals 24 hours or 86,400 seconds, approximating one rotation of the Earth. Calendars, deadlines and project plans are built on days.