Direct conversion
Convert day [d] to second [s] instantly with formula, examples, chart, and FAQs.
1 day [d] = 86400 second [s]
1 day [d] = 86400 second [s]
Example: 1 day [d] equals 86400 second [s].
Time conversions use second as the reference unit. Calendar-style values such as average month and average Gregorian year are approximate by definition.
Displayed results are rounded for readability. The calculator keeps enough precision for everyday use and switches to scientific notation for very large or very small values. Last reviewed: 2026-08-14.
The day is a time unit commonly treated as 24 hours for conversion purposes.
HistoryDays are based on Earth rotation and were standardized for calendars and timekeeping.
Current useDays are used for schedules, delivery estimates, project plans, travel, medicine timing, and calendars.
The second is the SI base unit of time.
HistoryThe second moved from astronomical definitions to an atomic definition for high precision.
Current useSeconds are used in science, sports timing, computing, navigation, media, and everyday clocks.
| day [d] | second [s] |
|---|---|
| 1 | 86400 |
| 2 | 172800 |
| 5 | 432000 |
| 10 | 864000 |
| 20 | 1728000 |
| 25 | 2160000 |
| 50 | 4320000 |
| 100 | 8640000 |
| 1000 | 86400000 |
Use this formula: 1 day [d] = 86400 second [s] Enter your value in the calculator and the result updates instantly.
1 day [d] equals 86400 second [s].
Yes. Use the swap button in the calculator or open the related reverse conversion link when it is listed on this page.