DIY Cost Tools
Rounding Calculator
Round a decimal number to a chosen decimal place, using ties away from zero. The prefilled example shows a useful result immediately.
Decimal places must be an integer from −6 to 6. Negative places round tens, hundreds, and larger positions. Number magnitude must not exceed 1 trillion.
How to use
Enter the required numbers, then select Calculate. Invalid inputs clear previous results and show an explanation. Answers display up to ten significant digits unless an exact integer factorization is shown.
Formula and explanation
For p decimal places, shift the decimal by p places, round the magnitude to the nearest integer, then shift back and restore the sign. Exact halfway values round away from zero. p = 0 rounds to whole numbers; p = −2 rounds to hundreds.
Worked example
123.4567 rounded to two decimal places is 123.46. The change is +0.0033. Under this tie rule, −1.25 rounded to one place becomes −1.3.
Important limitations
Uses JavaScript decimal input and floating-point arithmetic, with decimal exponent shifting to reduce common scaling errors. It is not arbitrary-precision accounting software. Displayed values do not retain trailing zeros; 1.20 appears as 1.2. Some measurement and accounting rules use different tie conventions.
Frequently asked questions
How do I round to the nearest hundred?
Enter −2 as decimal places.
How are negative halfway values handled?
They round away from zero, so −2.5 becomes −3 at zero decimal places.
Is this significant-figure rounding?
No. It rounds a specified decimal position.
Why are trailing zeros omitted?
Results display numeric values rather than a fixed-width decimal format.
Review notes
Reviewed October 1, 2026. Default outputs and boundary cases were independently checked. Blank, nonfinite, excessive, and calculator-specific invalid inputs were tested before publication. This is an educational tool; verify precision and domain assumptions for professional use.