Number Formatter

The integer part is split into groups of three digits counted from the right, then joined with your chosen separator. Any minus sign and prefix stay in front of the grouped digits, so 1234567 becomes 1,234,567 in US style.

Click the EU 1.234,56 button, which sets the thousands separator to a dot and the decimal mark to a comma. You can also type those characters into the two separator boxes yourself to get values like 1.234.567,89.

Yes. The Thousands box accepts any short string up to three characters, so you can type a space to produce the SI style grouping like 1 234 567 that many countries prefer.

Untick the decimal places checkbox and the number keeps exactly the decimals you typed, so 1234567.891 stays as 1,234,567.891. Tick it and set a count to round to a fixed number of places, for example 2 for currency.

When decimal places are on, the value is rounded to that many places using standard rounding, and trailing zeros are kept. So 99.5 with 2 places becomes 99.50, and 2.005 rounded to 2 places follows the binary floating point result the browser produces.

A single minus sign leads the output, placed before any prefix, and grouping applies only to the digits. So -2500 with a dollar prefix and 2 decimals reads -$2,500.00.

A tiny negative such as -0.001 rounded to 2 places becomes 0.00 with no minus sign, because a signed zero would be misleading. The minus only appears when at least one non-zero digit survives the rounding.

You can format very large values, but JavaScript numbers lose exact precision beyond about 9 quadrillion (2 to the 53rd power). Above that, some low-order digits may not be accurate, which is a limit of the number type rather than the grouping logic.

No. Formatting happens entirely in your browser as you type, so your numbers never leave your device. There is also a JSON API if you want the same formatting inside a script.