Convert Days to Seconds
Days to seconds is the conversion you need when a stretch of time measured in days has to be broken down into the smallest common unit — for timers, schedulers, or countdowns. One day is exactly 86,400 seconds, so the number gets much bigger when you switch from days to seconds.
Days to Seconds conversion table
| Days (d) | Seconds (s) |
|---|---|
| 1 | 86,400 |
| 2 | 172,800 |
| 3 | 259,200 |
| 5 | 432,000 |
| 10 | 864,000 |
| 20 | 1,728,000 |
| 50 | 4,320,000 |
| 100 | 8,640,000 |
| 500 | 43,200,000 |
| 1,000 | 86,400,000 |
The formula
To convert days to seconds, multiply the number of days by 86,400:
seconds = days × 86400
A worked example
Say you want to convert 3 days into seconds:
3 × 86400 = 259200 seconds
That's the kind of number you'd see in a countdown timer or a script that needs to sleep for 3 days.
Why the number is exact
A day is defined as exactly 24 hours, an hour as exactly 60 minutes, and a minute as exactly 60 seconds. Multiply those together — 24 × 60 × 60 — and you get 86,400 exactly, with no measurement or rounding involved. Every days-to-seconds conversion carries that same exactness.
When you'll use it
Setting timeouts and cache expirations in code, converting subscription or trial lengths into seconds for an API, and building countdown timers that need a raw second count.
Frequently asked questions
How many seconds are in a day?
Exactly 86,400 seconds. That comes from 24 hours, each made of 60 minutes, each made of 60 seconds — 24 × 60 × 60 = 86,400.
Is the days to seconds conversion exact?
Yes. A day is defined as exactly 24 hours, an hour as exactly 60 minutes, and a minute as exactly 60 seconds, so multiplying by 86,400 is precise with no rounding involved.
Why do computers often store time in seconds?
Seconds are the smallest common unit shared by every larger time period, so systems like Unix timestamps count seconds and convert up to minutes, hours, or days only when displaying the value to a person.