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Math / Rounding

Rounding Calculator

Round a decimal number to a chosen number of decimal places or significant figures. The result follows the common half-up rule for magnitude, while preserving a clear indication of the selected precision. For decimal places, scale by 10^d, round the magnitude at the halfway point upward, then restore the sign. Significant-figure mode derives the decimal place from the value’s order of magnitude.

Your inputs

Make it your own
Calculator settings

Your result
12.35
Rounded value
Places
2

Example inputs shown. Adjust them to explore.

A familiar situation

Round a measurement to the precision required on a label, estimate, or worksheet.

How to use this calculator

  1. Enter value, decimal places (−12 to 12).
  2. Select Calculate to see the answer and its breakdown.
  3. Keep a scenario, change an input and compare the results.

Use consistent units and check the assumptions below before applying the result.

How rounding is calculated

For decimal places, scale by 10^d, round the magnitude at the halfway point upward, then restore the sign. Significant-figure mode derives the decimal place from the value’s order of magnitude. Rounding 12.345 to two decimal places gives 12.35.

Round(|x|×10ᵈ) / 10ᵈ, then restore the sign; ties round away from zero.
A worked example

Rounding 12.345 to two decimal places gives 12.35.

Assumptions & useful context

The result depends on the values you enter and the method described above. Displayed numbers may be rounded; calculations use the unrounded values. Check that this model matches your situation before relying on it.

Frequently asked questions

Can decimal places be negative?

Yes; −1 rounds to tens, −2 to hundreds.

How is an exact tie treated?

Halfway cases round away from zero.

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