All tools › Rounding and notation
Rounding calculator
Six rules side by side, in exact decimal arithmetic, and a column that still adds up.
It runs entirely in this browser tab: what you type is never uploaded, and the tool makes no network request while it works. Open your browser's network panel and try it — nothing leaves the page. There is no sign-up and no limit beyond what your own browser can hold.
Settings
- Round to
- Choices: Decimal places, Nearest multiple, Order of magnitude.
- Decimal places
- How many digits after the point. A number from 0 to 20.
- Multiple of
- Five hundredths for cash rounding, a quarter for a fee, twenty-five for a paper size.
- Sort
- By value, not alphabetically — which is where a text sorter goes wrong. A number from -6 to 12.
- Rounding rule
- They only disagree at exactly a half — which is the whole of the argument. Choices: Half away from zero, Half to even, Down, Up, Towards zero, Away from zero.
- Show every rule at once
- A column of six is quicker to read than any explanation of why they differ.
- Keep the total
- Hands the difference out one step at a time, so a budget still adds up after rounding.
How to use it
- Paste your text into the box above, or open a file.
- Adjust the settings beside it until the result is what you wanted.
- Copy the result, or save it as a file. The result updates as you type.
Questions
- Is what I type uploaded anywhere?
- No. This page carries the whole tool as WebAssembly and runs it on your own device. Nothing you type is sent anywhere, and there is no network request to make while it works.
- How exact is the arithmetic?
- Exact, in decimal, for everything the tool was given: no value here is put through floating point on the way to the answer. Where there is a genuine ceiling — thirty-nine digits for the number-theory tools, a fixed number of places for a repeating fraction — the tool says the limit rather than quietly truncating.
- Can I get this result again later?
- The settings travel in the page's address, after the #, so a link reproduces them exactly — and the fragment of an address is never sent to a server. Your last settings are also remembered on this device, which is worth knowing before you paste a number you would not want left there.
- Is there a version that is not a web page?
- Yes. The same tools are built as a desktop application from the same code, with a save dialog instead of a download and no network code at all.
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