Round numbers to decimal places, nearest 10/100, or significant figures
Round a number to a specific number of decimal places.
Formula: round(3.14159265, 2) = 3.14
Rounding Methods
The standard method. 2.5 → 3, −2.5 → −2.
Always toward −∞. 2.9 → 2, −2.1 → −3.
Always toward +∞. 2.1 → 3, −2.9 → −2.
Drop the fraction. 2.9 → 2, −2.9 → −2.
The rounding calculator makes it easy to round any number exactly the way you need. Choose between rounding to a set number of decimal places (e.g. 2 for currency), rounding to the nearest 10, 100, 1000, or any custom factor, or rounding to significant figures for scientific work. Each mode also shows floor, ceiling, and truncation values side by side.
Rounding moves the number to the nearest value using the half-up rule (2.5 becomes 3). Truncating simply drops all digits beyond the chosen place, always moving toward zero — so 2.9 becomes 2 and −2.9 becomes −2, regardless of the fraction.
Select the 'Nearest 10 / 100 / …' tab, enter your number, and set the factor to 10, 100, or 1000. The formula is: round(number ÷ factor) × factor. For example, 1337 rounded to the nearest 100 is round(1337 ÷ 100) × 100 = 1300.
Significant figures are the meaningful digits in a number, counted from the first non-zero digit. They are used in science and engineering to express precision. For example, 0.004567 rounded to 3 significant figures is 0.00457 — the leading zeros are not significant.
This calculator uses the standard 'round half up' method (also called round half toward positive infinity). In this method the halfway point always rounds toward the larger value: 2.5 → 3 and −2.5 → −2. Some languages use 'round half to even' (banker's rounding) which behaves differently.