Seconds to Days Converter
86,400 seconds = 1 day exactly. Type in either box.
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86,400 seconds in a day
Twenty-four hours of 3,600 seconds gives 86,400. It is exact by definition, even though the Earth's actual rotation is slightly irregular and slowly slowing.
1 day = 86,400 seconds exactly
That mismatch between the definition and the planet is why leap seconds have occasionally been inserted, keeping atomic clocks in step with the Earth. For every purpose short of astronomy, a day is exactly 86,400 seconds.
Large second counts usually come from system uptime or Unix timestamps, and converting to days is the fastest way to make them readable: a million seconds is 11.57 days.
The second
The SI base unit of time. Since 1967 it has been defined by the caesium atom: 9,192,631,770 cycles of a particular transition. Every other unit of time on this page is built from it.
It is the only unit here that is fixed by physics rather than by convention.
The day
86,400 seconds by definition. The actual rotation of the Earth is slightly irregular and slowly slowing, which is why leap seconds have occasionally been added to keep clocks in step with the planet.
For every purpose short of astronomy, a day is exactly 86,400 seconds.
The working, step by step
Every line updates with whatever you type above. The point is the method, which is the same for any pair of units in this family.
The same quantity, two different numbers
One physical amount, read off two scales. The tick marks do not line up, and the gap between them is the conversion factor made visible.
How much is that?
A number is easier to judge next to something familiar.
Your turn
Reading a method and being able to use it are different things. Answer within half a per cent and it counts as correct.
Score: 0 of 0
How to use this converter
- Type into either box. The other side updates as you go; there is no button to press.
- Swap the direction with the button between the boxes, carrying your value across.
- Set the decimals if the default is more or less precision than you need.
- Copy the answer with its unit, ready to paste.
- Use the shortcut buttons for the values that come up most often.
- Share the result. The address bar tracks what you type, so the link you copy opens on the same number.
Common uses and tips
Where time conversions come up
- Project planning. Estimates arrive in hours and schedules run in days, so the two have to be reconciled constantly.
- Billing and payroll. Hours into minutes for timesheets, and back again for invoices.
- Programming. Timeouts, intervals and durations are set in milliseconds; humans think in seconds and minutes.
- Video and audio. Runtimes in minutes and seconds, timestamps in seconds, frame timings in milliseconds.
- Cooking, exercise and study timers, where the number on the timer and the number in the instructions rarely use the same unit.
Numbers worth carrying
- 3,600 seconds in an hour. It converts hours to seconds in one step and turns up all over physics.
- 86,400 seconds in a day. Exactly, by definition.
- 604,800 seconds in a week.
- 525,600 minutes in a common year, which is 365 days.
Where it stops being exact
Seconds, minutes, hours, days and weeks are fixed. A day is exactly 86,400 seconds and a week exactly seven days.
Months and years are not. A month runs from 28 to 31 days and a year is 365 or 366, so any conversion involving them uses an average: 30.436875 days per month and 365.2425 days per year, both from the Gregorian calendar.
That average is right across long spans and wrong for any specific date. For a contract, a deadline or a billing period, count the calendar rather than multiplying. The difference between an average month and a real February is over two days.
Mistakes worth avoiding
- Decimal hours are not hours and minutes. 1.5 hours is 1 hour 30 minutes, but 1.25 hours is 1 hour 15 minutes, not 1 hour 25.
- Leap years matter over long spans. Four years is 1,461 days, not 1,460.
- A "working day" is not a day. If you mean eight hours, say eight hours — conversions here use the full 24.
Values people look up most
Each one opens the converter with the number already in it.
- 3,600 s to d
- 10,000 s to d
- 43,200 s to d
- 86,400 s to d
- 100,000 s to d
- 172,800 s to d
- 259,200 s to d
- 604,800 s to d
- 1,000,000 s to d
- 2,592,000 s to d
- 31,536,000 s to d
Quick reference
| Seconds | Days |
|---|---|
| 3,600 s | 0.041667 d |
| 86,400 s | 1 d |
| 172,800 s | 2 d |
| 604,800 s | 7 d |
| 1,000,000 s | 11.574074 d |
| 2,592,000 s | 30 d |
| 31,536,000 s | 365 d |
Questions people ask
How many seconds in a day?
Exactly 86,400.
How many days is a million seconds?
11.57 days.
What is a leap second?
An extra second occasionally added to keep atomic time in step with the Earth's rotation, which is not perfectly regular.