Rounding calculator
Round any number to decimal places, significant figures or the nearest 10, 100 or 1,000, and see why it rounds the way it does.
Round to
Method
Standard: 5 or more rounds up
3.14159 rounded to 2 decimal places (nearest hundredth)
3.14
It is closer to 3.14 than to 3.15.
Calculators
A calculator for every kind of rounding
Decimals
Whole numbers
Guide
How to round numbers
- 1
Find the rounding place
Decide which digit you are rounding to: ones, tenths, hundredths and so on.
- 2
Look one digit to the right
That digit decides whether the rounding place stays or goes up by one.
- 3
5 or more rounds up
If it is 5–9, add one to the rounding place. If it is 0–4, leave it as it is.
- 4
Drop the rest
Remove every digit after the rounding place. Whole numbers fill those places with zeros.
3.14159 to 2 decimal places
3.14159→3.14
Next digit is 1, less than 5, so keep 4.
7.856 to 1 decimal place
7.856→7.9
Next digit is 5, so 8 goes up to 9.
Rules
Four rounding methods
Half up
Standard rounding
Digits of 5 or more round up, below 5 round down.
- 2.4
- → 2
- 2.5
- → 3
- -2.5
- → -3
Up
Ceiling
Always move to the larger neighbour, whatever the next digit is.
- 2.1
- → 3
- 2.9
- → 3
- -2.1
- → -2
Down
Floor
Always move to the smaller neighbour, whatever the next digit is.
- 2.9
- → 2
- 2.1
- → 2
- -2.9
- → -3
Half even
Banker's rounding
Exact halves go to the even neighbour, which avoids drift when you round many values.
- 2.5
- → 2
- 3.5
- → 4
- 4.5
- → 4
Which one to use: half up for everyday maths, up for safety margins and capacity, down for budgets and conservative estimates, half even for finance and statistics where many rounded values are added together.
Guide
Significant figures
Significant figures are the digits that carry meaning about a measurement’s precision. Rounding to significant figures keeps that precision honest in scientific work.
| Rule | Example | Sig figs |
|---|---|---|
| Non-zero digits always count | 123.45 | 5 |
| Zeros between non-zero digits count | 1002 | 4 |
| Trailing zeros after a decimal point count | 1.200 | 4 |
| Leading zeros never count | 0.0025 | 2 |
| Trailing zeros in whole numbers are ambiguous | 1200 | 2–4 |
| Number | To 3 sig figs |
|---|---|
| 123.456 | 123 |
| 0.012345 | 0.0123 |
| 1234.5 | 1230 |
| 9876 | 9880 |
| 1.2 | 1.20 |
Scientific notation removes the ambiguity: 1.20 × 10³ has three significant figures.
FAQ
Frequently asked questions
How accurate is this rounding calculator?
The main calculator works on the digits you type rather than on floating-point numbers, so it avoids the classic errors where 1.005 or 2.675 round the wrong way. Results are exact for any length of number.
Do you store my calculations?
No. All calculations run in your browser. The numbers you enter are never sent to or stored on our servers.
What is the difference between standard rounding and banker's rounding?
Standard rounding (half up) rounds an exact half up, so 2.5 becomes 3. Banker's rounding (half to even) rounds an exact half to the nearest even digit, so 2.5 becomes 2 and 3.5 becomes 4. This removes the upward bias when many values are rounded and added together.
How do negative numbers round?
Half up rounds exact halves away from zero, so -2.5 becomes -3. Round up always moves toward the larger value (-2.1 becomes -2) and round down toward the smaller value (-2.1 becomes -3).
What are significant figures and why do they matter?
Significant figures are the digits that carry information about how precise a number is. Rounding a calculated result to the right number of significant figures avoids claiming more precision than your measurements have.
Can I round a list of numbers at once?
Yes. The bulk rounding calculator takes a list of numbers, one per line, and rounds them all with the same settings.
Is it free?
Yes. Every calculator and guide on the site is free to use, with no sign-up.