conversions
How Many Seconds in a Day
Last updated: May 31, 2026
Written by Blake Boege
A seconds-in-a-day calculation converts calendar days into seconds by multiplying 24 hours per day, 60 minutes per hour, and 60 seconds per minute. This yields exactly 86,400 seconds. While atomic clocks and Coordinated Universal Time (UTC) occasionally add leap seconds to match Earth's variable rotation, standard calculations assume 86,400 seconds per solar day.
Calculate exact time intervals. Convert between days, hours, minutes, and seconds instantly, and learn the math behind standard calendar day calculations.
Quick Answer
Find the exact number of seconds in a standard 24-hour day (86,400 seconds) and convert any day or second duration instantly.
How Many Seconds in a Day?
There are exactly 86,400 seconds in a 24-hour day.
This is based on the standard division of a day into 24 hours, with each hour containing 60 minutes, and each minute containing 60 seconds.
24 hr
1440 min
Formula: 1 Day = 24 Hours × 60 Minutes × 60 Seconds = 86,400 Seconds
Time Intervals to Seconds Table
| Time Interval | Seconds (s) |
|---|---|
| 1 Minute | 60 s |
| 1 Hour | 3,600 s |
| 1 Day | 86,400 s |
| 1 Week (7 Days) | 604,800 s |
| 1 Month (Average) | 2,629,743 s |
| 1 Standard Year (365 Days) | 31,536,000 s |
| 1 Leap Year (366 Days) | 31,622,400 s |
Examples
1 Day
86,400 seconds
1 Hour
3,600 seconds
1 Week
604,800 seconds
How it works
The number of seconds in a standard calendar day is computed by multiplying the time units together:
The Calculation
60 seconds/min × 60 minutes/hour × 24 hours/day
= 86,400 seconds
How the Math Breaks Down
To understand the size of these time intervals, we build them up step-by-step:
- 1 Minute = 60 Seconds
- 1 Hour = 60 Minutes × 60 Seconds = 3,600 Seconds
- 1 Day = 24 Hours × 3,600 Seconds = 86,400 Seconds
Earth Rotation vs. Atomic Time (Leap Seconds)
While a standard calendar day is defined as exactly 86,400 seconds, the actual time it takes for the Earth to complete one full rotation on its axis relative to the sun (a solar day) fluctuates slightly due to tidal friction and other geophysical factors.
To keep our precise atomic clocks synchronized with the Earth's physical rotation, scientists at the International Earth Rotation and Reference Systems Service occasionally insert a "leap second" at the end of June or December. This ensures our clocks do not drift away from solar noon.
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Frequently asked questions
There are 604,800 seconds in a full 7-day week (86,400 seconds/day × 7 days).
A standard 365-day year contains 31,536,000 seconds. A leap year of 366 days contains 31,622,400 seconds.
There are 86,400,000 milliseconds in a day (86,400 seconds × 1,000 milliseconds per second).
A leap second is a one-second adjustment occasionally applied to Coordinated Universal Time (UTC) to keep it in sync with the Earth's slightly variable rotation speed. When a leap second is added, that day contains 86,401 seconds.
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