Rounding Calculator
Round numbers to any decimal place, significant figures, or nearest integer.
Rounding Methods
Rounding replaces a precise number with a simpler approximation. Round half up (the most common method): if the digit being dropped is 5 or more, round the preceding digit up — 2.45 rounds to 2.5, 2.44 rounds to 2.4. Round half down: if the digit is exactly 5, round down — used in some accounting contexts. Round half to even (banker's rounding): round 5 toward the nearest even number — 2.5 rounds to 2, 3.5 rounds to 4. This method reduces cumulative rounding bias when many values are rounded and is the default in many financial and scientific computing systems.
Decimal Places vs. Significant Figures
Rounding to decimal places specifies how many digits appear after the decimal point. 3.14159 rounded to 2 decimal places is 3.14. Rounding to significant figures specifies the total number of meaningful digits. 3.14159 rounded to 4 significant figures is 3.142. For a number like 0.00456, rounding to 2 decimal places gives 0.00 (eliminating all meaningful digits), while rounding to 2 significant figures gives 0.0046 (preserving meaning).
Rounding to Nearest 10, 100, 1000
Rounding to a large place value removes decimal precision and replaces trailing digits with zeros. 4,728 rounded to the nearest 100 is 4,700 (the hundreds digit is 7, the tens digit is 2 which is less than 5, so round down). 4,780 rounded to the nearest 100 is 4,800 (the tens digit is 8, which is 5 or more, so round up). This kind of rounding is common in estimates, budgets, and statistical reports.
Frequently Asked Questions
What are significant figures?
Significant figures are the meaningful digits in a number. 0.0045 has 2 sig figs (4 and 5). 1200 is ambiguous (could be 2, 3, or 4 sig figs) u2014 scientific notation resolves this: 1.2 u00d7 10u00b3 has 2 sig figs.
When do you round up a 5?
In standard rounding (round half up), a 5 always rounds up. In banker's rounding (round half to even), a 5 rounds to the nearest even digit. Both are valid u2014 context determines which to use.