Convert Days to Seconds
Convert Days to Seconds instantly. 1 Day (d) equals 86,400 Seconds (s).
Days to Seconds conversion table
| Days (d) | Seconds (s) |
|---|---|
| 1 d | 86,400 s |
| 2 d | 172,800 s |
| 3 d | 259,200 s |
| 5 d | 432,000 s |
| 10 d | 864,000 s |
| 20 d | 1,728,000 s |
| 50 d | 4,320,000 s |
| 100 d | 8,640,000 s |
| 500 d | 43,200,000 s |
| 1,000 d | 86,400,000 s |
1 Day = 86,400 Seconds · multiply Days by 86,400
About converting Days to Seconds
Days (d) and Seconds (s) are both units of time, so converting between them is a single multiplication: multiply your Days figure by 86,400. Ten Days comes to 864,000 Seconds, and a hundred works out at 8,640,000 Seconds.
Rule of thumb: going from Days to Seconds multiplies, so the figure always grows — one Day is already 86,400 Seconds. If your answer came out smaller, you have the conversion the wrong way round.
What is a Day?
A day is exactly 86,400 seconds — and that is a statement about the unit, not about the Earth. A real solar day varies slightly depending on winds, tides and what the planet’s core is doing, and tidal friction is gradually lengthening it. The gap between the tidy unit and the untidy planet is what leap seconds patch over. Astronomers also distinguish the solar day from the sidereal day, one full rotation relative to the stars, which is about four minutes shorter because the Earth has meanwhile moved along its orbit.
What is a Second?
The second is the SI base unit of time and the reference every other unit here is measured against. It was originally 1/86,400 of a mean solar day, but the Earth’s rotation is not steady enough to serve as a clock, so since 1967 the second has been defined by the caesium-133 atom: 9,192,631,770 periods of a specific hyperfine transition. Atomic time and Earth time therefore drift apart, which is why leap seconds are occasionally inserted to realign them — a fiddly practice that in 2022 was agreed to be phased out by 2035.
To put both in perspective: a day is one turn of the Earth on its axis, while a human heartbeat takes about a second.
The converter above updates as you type, and the table lists common values for quick reference. Need the opposite direction? Use the Seconds to Days converter, or browse all Time converters.
Frequently asked questions
How many Seconds are in one Day?
There are 86,400 Seconds in one Day.
How do I convert Days to Seconds?
Multiply the number of Days by 86,400. For example, 10 Days = 864,000 Seconds.
What is 100 Days in Seconds?
100 Days is equal to 8,640,000 Seconds.
How do I convert Seconds to Days?
Multiply the Seconds value by 0.00001157 (or divide by 86,400).
Is this Days to Seconds conversion exact?
Yes, exactly. Both units are fixed against the same base by definition, and 1 Day = 86,400 Seconds is the complete value — nothing is rounded away.
What is a Day?
A day is exactly 86,400 seconds — and that is a statement about the unit, not about the Earth. A real solar day varies slightly depending on winds, tides and what the planet’s core is doing, and tidal friction is gradually lengthening it. The gap between the tidy unit and the untidy planet is what leap seconds patch over. Astronomers also distinguish the solar day from the sidereal day, one full rotation relative to the stars, which is about four minutes shorter because the Earth has meanwhile moved along its orbit.
What is a Second?
The second is the SI base unit of time and the reference every other unit here is measured against. It was originally 1/86,400 of a mean solar day, but the Earth’s rotation is not steady enough to serve as a clock, so since 1967 the second has been defined by the caesium-133 atom: 9,192,631,770 periods of a specific hyperfine transition. Atomic time and Earth time therefore drift apart, which is why leap seconds are occasionally inserted to realign them — a fiddly practice that in 2022 was agreed to be phased out by 2035.