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- Rounds any number to tens, hundreds, thousands or up to 6 decimal places.
- Rounds to a chosen number of significant figures.
- Supports half up, half to even (banker’s), ceiling, floor and truncate.
- Shows the same number rounded to several other places for comparison.
How to use the rounding calculator
Enter your number
Type any positive or negative number, such as 3.14159 or 1234567.
Choose what to round to
Pick a place value like hundredths or nearest thousand, or choose significant figures and enter how many.
Pick a rounding rule (optional)
Standard half up is used by default. Open the option to switch to banker’s rounding, ceiling, floor or truncate.
Read the result
You see the rounded value, the rounding error, which two values it sits between, and a table of other places.
How rounding works
Find the digit in the place you are rounding to, then look at the next digit to its right. With the standard rule, if that digit is 5 or more you round up, and if it is 4 or less you round down. Every digit after the rounding place becomes zero or is dropped.
Rounding rules compared
Half up: 2.5 → 3, −2.5 → −3 (ties move away from zero)
Half to even: 2.5 → 2, 3.5 → 4 (ties go to the even digit)
Ceiling: always up, 1.21 → 1.3
Floor: always down, −1.21 → −1.3
Truncate: cut off the digits, −1.29 → −1.2
Banker’s rounding is used in finance and many programming languages because it avoids pushing totals upward when many values end in 5.
Example 1: decimal places
Round 3.14159 and 2.675 to two decimal places (hundredths).
- 3.14159 3.14 (next digit 1, round down)
- 2.675 2.68 (next digit 5, round up)
Some spreadsheets and programming languages show 2.67 for 2.675 because of how computers store decimals. This calculator corrects for that and gives the textbook answer.
Example 2: large place values
Round 1,234,567 to the nearest thousand.
- Thousands digit 4
- Next digit 5, so round up
- Result 1,235,000
The number lies between 1,234,000 and 1,235,000 and is closer to the upper value.
Example 3: significant figures
Significant figures count from the first non-zero digit.
- 0.000123456 to 3 s.f. 0.000123
- 98,765 to 2 s.f. 99,000
- 3.14159 to 3 s.f. 3.14
Leading zeros are never significant, which is why 0.000123 still has three significant figures.
Where a rounding calculator helps
Maths homework
Check rounding to decimal places, place values and significant figures with the working shown.
Science and lab work
Report results to the right number of significant figures for your measurements.
Money and invoices
Round prices and totals to cents, or try banker’s rounding to match accounting software.
Estimating
Round big numbers to the nearest thousand or million to make quick mental estimates.
To write very large or very small numbers compactly, use the scientific notation calculator. For reporting experiment results, pair rounding with the percent error calculator, and use the average calculator to find a mean before you round it.
Rounding calculator FAQ
How do you round to two decimal places?
Look at the third decimal digit. If it is 5 or more, add 1 to the second decimal digit. If it is 4 or less, leave it. Then drop the rest. So 3.14159 becomes 3.14.
Does 5 round up or down?
Under the standard half up rule, 5 rounds up. Under banker’s rounding (half to even), 5 rounds to the nearest even digit, so 2.5 becomes 2 and 3.5 becomes 4.
How do I round negative numbers?
With half up, ties move away from zero, so −2.5 becomes −3. Floor always moves toward negative infinity and ceiling toward positive infinity.
What are significant figures?
They are the meaningful digits in a number, counted from the first non-zero digit. 0.00452 has three significant figures.
What is the difference between rounding and truncating?
Rounding looks at the next digit to decide the direction. Truncating simply cuts off the extra digits, so 1.29 truncated to one decimal is 1.2, while rounded it is 1.3.
Why does 2.675 sometimes round to 2.67 on a computer?
Computers store 2.675 as a value slightly below it, such as 2.67499999…. This calculator cleans up that tiny error so 2.675 rounds to 2.68 as expected.