86400 x 1000 = 86400000
86400 times 1000 is 86400000. That is the number of milliseconds in a day, which is why this particular pair gets looked up so often. Working, unit list and calculator below.
86,400 × 1,000 = 86,400,000
Adding 86,400 to itself 1,000 times gives the same answer.
86400 x 1000 = 86400000
Three zeros go on the end: 86,400,000. In scientific notation that is 8.64 x 10 to the seventh.
Why anyone multiplies 86400 by 1000
86400 is the number of seconds in a day, from 24 x 60 x 60. Multiplying by 1000 converts seconds to milliseconds, so 86400000 is the number of milliseconds in a day. Almost everyone running this calculation is writing code and needs one day expressed in the unit their language uses.
- JavaScript timestamps count milliseconds, so one day from now is Date.now() plus 86400000.
- A cookie Max-Age is measured in seconds, so a one-day cookie takes 86400, not 86400000. Feeding one unit where the other belongs is the classic bug.
- setTimeout and setInterval also take milliseconds.
The rest of the units
- One hour: 3600 seconds, 3600000 milliseconds.
- One day: 86400 seconds, 86400000 milliseconds.
- One week: 604800 seconds, 604800000 milliseconds.
- Thirty days: 2592000 seconds, 2592000000 milliseconds.
Divide 86400000 by 3600000 and you get 24 back, which is a quick sanity check on the whole thing.
Related conversions
1000 x 1000 = 1000000 is the same step one size down, the microseconds in a second. 10000 x 1000 is the next size up. Everything else is on multiplication answers.