Convert Day to Second (d → s)
The day equals 24 hours and is the fundamental unit of human routine, calendars, and Earth rotation.
Day to Second Conversion Table
10 common values| Day | Second |
|---|---|
| 1 d | 86,400 s |
| 5 d | 432,000 s |
| 10 d | 864,000 s |
| 30 d | 2,592,000 s |
| 60 d | 5,184,000 s |
| 120 d | 10,368,000 s |
| 300 d | 25,920,000 s |
| 600 d | 51,840,000 s |
| 1,800 d | 155,520,000 s |
| 3,600 d | 311,040,000 s |
How to Convert Day to Second Manually
Step by StepConverting days to seconds is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.
- 1Take your value in daysStart with the number of days (d) you want to convert.
- 2Multiply by 86,400The conversion factor from d to s is 86,400. Multiply your value by this number.
- 3Read the result in secondsThe result is your value in seconds (s).
Formula
Multiply the value in days by 86,400. For the reverse direction, multiply by 0.00001157.
s = d × 86,400d = s × 0.00001157Tips
Use these in everyday conversions- 1 day = 24 hours = 1440 minutes = 86,400 seconds.
- Julian day count is used in astronomy from 4713 BC.
- A sidereal day is 23 h 56 min 4 s — slightly shorter than a solar day.
Common Mistakes
Avoid these- Confusing sidereal and solar days in astronomy.
- Assuming a day is always exactly 24 h — leap seconds (rare) and timezone shifts vary.
- Mixing business days and calendar days in contracts.
About Day and Second
What is the Day?
The day equals exactly 86,400 seconds (24 hours) — the mean time for Earth to complete one rotation relative to the Sun (the 'solar day'). The 'sidereal day' (relative to distant stars) is about 4 minutes shorter at 23 hours, 56 minutes, 4 seconds, but everyday usage refers to the solar day. Days are the fundamental unit of human routine: sleep cycles, work schedules, calendar appointments, and project timelines all measure in days. The day relates to the second (86,400 s = 1 day), the hour (24 h = 1 day), and the week (7 days = 1 week). Earth's rotation gradually slows due to tidal friction, lengthening the day by about 1.7 milliseconds per century — leap seconds are occasionally added to civil time to compensate, though this practice will end by 2035 by international agreement.
- Calendar dates and scheduling
- Shipping and delivery times
- Medical dosing intervals (e.g. "once daily")
International shipping: 2–7 days typical. Global work-week: 5 days in most countries. Human circadian rhythm: 24 h ± 30 min.
What is the Second?
The second is the base SI unit of time. Since 1967, it has been defined by atomic physics: the duration of 9,192,631,770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium-133 atom. This makes the second extraordinarily reproducible — modern atomic clocks based on optical transitions can keep time to a few parts in 10¹⁸. The second is the foundation of all time measurements: the minute (60 s), the hour (3,600 s), the day (86,400 s). It is also fundamental in physics — speeds (m/s), accelerations (m/s²), frequencies (Hz = 1/s), and Planck's constant all reference the second. International civil time, GPS, and the internet's time synchronization all depend on cesium-based atomic seconds. The second relates to the millisecond (1,000 ms = 1 s), the microsecond, and the nanosecond.
- Everyday timekeeping
- Scientific and engineering measurements
- Sports timing (100 m sprint in ~10 s)
A blink takes 100–400 ms. Heartbeat at rest ~1 s. The 100 m sprint world record is 9.58 s (Usain Bolt).