How to convert milliseconds to seconds with precision

java precision divide milliseconds
Keir Nellyer picture Keir Nellyer · Dec 30, 2012 · Viewed 106.6k times · Source

I want to convert milliseconds to seconds (for example 1500ms to 1.5s, or 500ms to 0.5s) with as much precision as possible.

Double.parseDouble(500 / 1000 + "." + 500 % 1000); isn't the best way to do it: I'm looking for a way to get the remainder from a division operation so I could simply add the remainder on.

Answer

Jon Skeet picture Jon Skeet · Dec 30, 2012

Surely you just need:

double seconds = milliseconds / 1000.0;

There's no need to manually do the two parts separately - you just need floating point arithmetic, which the use of 1000.0 (as a double literal) forces. (I'm assuming your milliseconds value is an integer of some form.)

Note that as usual with double, you may not be able to represent the result exactly. Consider using BigDecimal if you want to represent 100ms as 0.1 seconds exactly. (Given that it's a physical quantity, and the 100ms wouldn't be exact in the first place, a double is probably appropriate, but...)

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