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Rounding Numbers Calculator

Work out rounding numbers instantly with clear inputs, formula shown and shareable results.

About Rounding Numbers Calculator

Rounding to d decimal places multiplies by 10^d, rounds to the nearest whole number and divides back. Significant figures instead count from the first non-zero digit, so the place value depends on the size of the number.

Formulas

Round to d places

round(v × 10^d) / 10^d

Significant figures

scale so the first significant digit is in the units place, round, then scale back

Worked example

With the default values below, Rounding Numbers Calculator returns Rounded to the nearest of 3.140000000000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Value
3.14159
Decimal placesaccepts 0–12
2
Significant figuresaccepts 1–15
3

Results

Rounded to the nearest
3.140000000000
Rounded down (floor)
3.140000000000
Rounded up (ceiling)
3.150000000000
To significant figures
3.140000000000

Step by step

  1. 1Values used
  2. 2Round to d places
  3. 3Significant figures
  4. 4Rounded to the nearest= 3.140000000000
  5. 5Rounded down (floor)= 3.140000000000
  6. 6Rounded up (ceiling)= 3.150000000000
  7. 7To significant figures= 3.140000000000

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 12 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

π to 2 decimal places and 3 significant figures?

Both give 3.14 here, but for 0.00314159 two decimal places gives 0.00 while three significant figures gives 0.00314.

How are halfway values handled?

This uses round-half-up, so 2.5 becomes 3. Statistical work sometimes prefers round-half-to-even instead.

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