The units of time, laid out cleanly: how many seconds are in a minute, an hour, a day, a week and a year — plus the reverse lookups people search for most, the handful of numbers worth memorising, and why a year never quite lands on a round figure.
A minute is 60 seconds · an hour is 3,600 · a day is 86,400.
From there everything stacks: a week is 604,800 seconds, and a common year is 31,536,000. The only unit that won't behave is the month — its length jumps between 28 and 31 days.
Read across each row to turn one of that unit into seconds, minutes, hours and days. Every number is exact except the year, where a leap year adds one more day.
| One… | Seconds | Minutes | Hours | Days |
|---|---|---|---|---|
| Minute | 60 | 1 | 0.0167 | — |
| Hour | 3,600 | 60 | 1 | 0.0417 |
| Day | 86,400 | 1,440 | 24 | 1 |
| Week | 604,800 | 10,080 | 168 | 7 |
| Year (365) | 31,536,000 | 525,600 | 8,760 | 365 |
| Leap year | 31,622,400 | 527,040 | 8,784 | 366 |
A month isn't in the table on purpose — there's no single answer. An average calendar month is about 30.44 days (a year split twelve ways), roughly 730.5 hours or 2,629,800 seconds, but any given month is 28, 29, 30 or 31 days.
Four constants cover almost every everyday calculation. Lock these in and you can do the rest in your head:
The famous one is 525,600 — the minutes in a year, immortalised by the song Seasons of Love. It's just 365 × 24 × 60.
Most "how many X in a Y" questions are one of these:
This is the quickest way to feel how much bigger a billion is than a million — the gap is enormous, and seconds make it land:
| This many seconds… | …is roughly |
|---|---|
| 1,000,000 (a million) | about 11½ days — exactly 11 days, 13 hours, 46 minutes, 40 seconds |
| 1,000,000,000 (a billion) | about 31¾ years — close to 31 years and 8 months |
| 1,000,000,000,000 (a trillion) | about 31,700 years — older than the last Ice Age |
A million seconds was last week; a billion seconds ago you weren't born yet (or were very small); a trillion seconds reaches back deep into prehistory. Same words, wildly different scales — that thousand-times jump at each step is exactly why "million" and "billion" are so easy to confuse and so worth keeping straight.
The Earth doesn't take a tidy 365 days to circle the Sun — it takes about 365.2425 days. That quarter-day a year is why we add a leap day to February roughly every four years: four spare quarters make one whole day. Without it the calendar would drift away from the seasons by about a day every four years.
So a year is either 365 days (common) or 366 (leap). For which years get the extra day — and why 2000 was a leap year but 1900 wasn't — see is 2026 a leap year?
52 weeks is 364 days — one short of a common year and two short of a leap year. That leftover day is why each date shifts forward a weekday from one year to the next, and why the ISO week-numbering system occasionally needs a 53rd week to mop up the slack. In decimal terms a year is about 52.14 weeks (or 52.29 in a leap year).
For the full picture of how the weeks are numbered, see how many weeks are in a year?
Seconds, minutes, hours, days and weeks all nest neatly inside each other. Months don't: they range from February's 28 (or 29) up to 31, so "a month" can mean anywhere from 2,419,200 to 2,678,400 seconds. When you need exact spans across uneven months, count the actual dates rather than multiplying an average.
For the length of each one, see how many days in each month? — and for the ways the world writes those dates out, date formats explained.
Knowing the units is half the job — the other half is counting actual calendar dates, which is what the week.hako.to calculators do for you. Use days between two dates to measure a span, add or subtract days to land on a future date, or the countdown to see how long until a deadline — all in your browser, nothing sent anywhere.
← Back to the week toolsAll figures use the standard 60-second minute and the Gregorian calendar used worldwide today. This page is fixed reference data — nothing you read here is sent anywhere.