Rounding Calculator
Round numbers to decimal places, significant figures, or the nearest 10, 100, or 1000. Also shows truncated, ceiling, and floor values.
Rounded Result
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Truncated
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Ceiling
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Floor
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What is Rounding Calculator?
The rounding calculator rounds any number according to your chosen method: decimal places, significant figures, or the nearest integer, 10, 100, or 1000. It also shows the truncated value, ceiling (round up), and floor (round down) for comparison.
How to use
- 1 Enter the number you want to round.
- 2 Select the rounding method from the dropdown.
- 3 Enter the number of decimal places or significant figures if applicable.
- 4 Click Calculate to see the rounded result.
- 5 Compare with truncated, ceiling, and floor values shown below.
Formula
Example calculation
Round 3.14159 to 3 decimal places: 3.142. To 3 significant figures: 3.14. To nearest 10: 0. Truncated: 3. Ceiling: 4. Floor: 3.
Frequently asked questions
What is the difference between rounding and truncating?
Rounding adjusts the last kept digit based on the next digit (≥5 rounds up). Truncating simply drops all digits after the cutoff point, always rounding toward zero.
What are significant figures?
Significant figures are the meaningful digits in a number, starting from the first non-zero digit. For example, 0.00423 has 3 significant figures (4, 2, 3).
What is ceiling vs floor rounding?
Ceiling always rounds up to the nearest integer (e.g., 3.1 → 4, −3.1 → −3). Floor always rounds down (e.g., 3.9 → 3, −3.1 → −4). These are mathematical ceiling and floor functions.
When should I round to significant figures vs decimal places?
Use significant figures in scientific and engineering contexts where the precision of the measurement matters. Use decimal places in financial and everyday calculations.
What is banker's rounding?
Banker's rounding (round half to even) rounds 0.5 to the nearest even number to reduce cumulative bias. This calculator uses standard rounding (half up).