Days to Seconds Converter
Unit ConversionConvert days to seconds (1 day = 86,400 seconds). Free converter with the formula, a conversion chart, and worked examples.
Seconds
Equivalent duration in seconds
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SponsoredTo convert days to seconds, multiply the number of days by 86,400. This calculator does it instantly: enter any day value above and the seconds equivalent updates as you type. For example, 3 days is 259,200 seconds.
A day is 24 hours, each hour is 60 minutes, and each minute is 60 seconds, so one day equals 24 × 60 × 60 = 86,400 seconds. Converting days to seconds is common in physics and chemistry problems, in programming (timeouts, cache lifetimes, and Unix timestamps are all counted in seconds), and in framing how much time a single day really holds.
Quick answer: 1 day = 86,400 seconds, 2 days = 172,800 seconds, 10 days = 864,000 seconds, and 100 days = 8,640,000 seconds.
This page covers days to seconds only. The related converters further down the page handle the reverse direction and the rest of the time unit family.
How to Convert Days to Seconds
The formula is: seconds = days × 86,400 (24 hours × 60 minutes × 60 seconds).
Worked example: 3 days is 259,200 seconds.
To go the other way, use the Seconds to Days Converter, which divides by 86,400 instead of multiplying.
How Many Seconds Are in a Day?
There are exactly 86,400 seconds in a standard day. Multiply 24 hours by 3,600 seconds per hour (60 minutes × 60 seconds) and you get 86,400.
The second was originally defined as 1/86,400 of a mean solar day before it was redefined using atomic clocks. Because the rotation of Earth is slightly irregular, timekeepers have occasionally added a leap second, making a rare day 86,401 seconds long, but calendar and code conversions always use 86,400.
Seconds in Longer Periods
| Period | Seconds |
|---|---|
| 1 hour | 3,600 |
| 1 day | 86,400 |
| 1 week | 604,800 |
| 30 days | 2,592,000 |
| 1 year (365 days) | 31,536,000 |
| 1 year (365.25 days) | 31,557,600 |
Days to Seconds Conversion Table
Common values in days and their equivalents in seconds:
| Days | Seconds |
|---|---|
| 0.25 days | 21,600 seconds |
| 0.5 days | 43,200 seconds |
| 1 day | 86,400 seconds |
| 2 days | 172,800 seconds |
| 3 days | 259,200 seconds |
| 5 days | 432,000 seconds |
| 7 days | 604,800 seconds |
| 10 days | 864,000 seconds |
| 30 days | 2,592,000 seconds |
| 100 days | 8,640,000 seconds |
| 365 days | 31,536,000 seconds |
Where Days to Seconds Conversion Is Used
Developers convert days to seconds all the time: a cookie or cache that expires in 30 days needs a max age of 2,592,000 seconds, and many APIs and scheduling tools take durations in seconds. Students meet the same conversion in unit analysis problems that chain days, hours, minutes, and seconds.
To count the days between two dates, use the Date Difference Calculator. To count only business days, use the Working Days Counter.
Frequently Asked Questions
How many seconds is 4 days?
345,600 seconds, since each day has 86,400 seconds.
How many seconds are in a month?
About 2,629,800 seconds on average (30.4375 days times 86,400). A 30 day month has exactly 2,592,000 seconds and a 31 day month has 2,678,400.
Can a days to seconds result be negative?
No. A duration cannot be negative, so a value below zero shows a dash instead of a result.
How many days is a million seconds?
1,000,000 seconds is about 11.57 days (1,000,000 divided by 86,400), or 11 days, 13 hours, 46 minutes, and 40 seconds. A billion seconds is about 11,574 days, roughly 31.7 years.
Can I convert days to seconds in Excel?
Yes. Multiply by 86,400 (for example =A1*86400), or use the built in function =CONVERT(A1,"day","sec"), where "day" and "sec" are the unit codes Excel uses for days and seconds.
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