Rounding Calculator
Free, with no sign up. Calculations run on your device; your entries stay in this browser.
Enter up to 200 digits with an optional exponent from −200 to 200. Decimal places range from −200 to 200. Choose negative places for a place-value multiple of ten: −1 rounds to tens, −2 to hundreds. Positive places retain trailing zeros in the answer. Exact BigInt arithmetic avoids binary-float tie errors. This rounds to powers of ten, rather than arbitrary increments or significant figures.
Your result
Round x to the nearest multiple of 10^−places. Compare the discarded remainder with half that multiple. At an exact tie, half-away increases the absolute retained integer; half-even increases it only when that integer is odd. Restore the original sign; rounded zero has no minus sign.
Primary source: General Decimal Arithmetic, rounding modes and arithmetic model.
Worked example
At zero decimal places, -2.5 becomes -3 with half-away and -2 with half-even. With half-even, 3.5 becomes 4. Rounding 125 to tens (places = −1) gives 130 half-away or 120 half-even.
How to use this tool
Enter the decimal, choose places and a halfway rule, then Calculate.
Frequently asked questions
How are negative ties handled?
Half-away rounds -2.5 to -3, while half-even rounds it to -2. Half-even chooses the result whose retained integer is even.
How do I round to hundreds?
Set decimal places to -2. Negative places select powers of ten to the left of the decimal point.
Is this free and private?
Yes. These calculations run in your browser, without sign-up or uploading your entries.