Rounding Calculator
Round positive or negative numbers to decimal places, whole places, tens, hundreds, or beyond.
Content updated August 1, 2026
Nearest rounding sends exact halfway cases away from zero. Other methods state their direction explicitly so negative values are not ambiguous.
Rounding replaces a number with a nearby value at a chosen place. Positive decimal-place settings keep digits after the decimal point, zero rounds to a whole number, and negative settings round to tens, hundreds, thousands, and larger places.
Choose the direction as well as the place. Nearest uses the familiar half-away-from-zero rule, while up, down, and toward zero have deliberately different behavior for negative numbers.
The Rounding formula
Rounded value = R(x × 10^d) ÷ 10^dx = original number · d = selected decimal places, which may be negative · R = the selected integer-rounding rule.
Worked example
For x = 1.005 and d = 2, nearest half-away-from-zero rounding keeps hundredths and returns 1.01. For 1,234.56 with d = −2, it rounds at the hundreds place and returns 1,200.
Assumptions, rounding, and limitations
Assumptions
- Input and output use the same unit.
- Nearest resolves exact halfway cases away from zero.
- Up and down mean toward positive and negative infinity respectively.
Rounding: The selected rounding rule is applied after exponent shifting; the display preserves the requested decimal places.
Limitations
- Supports decimal-place settings from −15 through 15 and magnitudes up to one quadrillion in the interface.
- JavaScript numbers use IEEE 754 binary floating-point representation, so extremely precise source decimals may already be approximations when entered.
Why rounding direction matters
For positive values, rounding up increases the result and rounding down decreases it. With negative values, up means toward positive infinity and down means toward negative infinity, so −2.341 rounded up to hundredths is −2.34, while rounded down it is −2.35.
Truncation simply removes digits beyond the selected place by moving toward zero. It is not the same as floor for negative numbers.
Frequently asked questions
▶How do I round to the nearest whole number?
Set decimal places to 0 and choose Nearest. Exact halfway cases such as 2.5 and −2.5 round away from zero to 3 and −3.
▶How do I round to the nearest hundred?
Set decimal places to −2. A setting of −1 means tens, −2 means hundreds, and −3 means thousands.
▶What is the difference between floor and truncate?
Floor rounds toward negative infinity; truncate rounds toward zero. For −2.9 at the whole-number place, floor gives −3 and truncate gives −2.
▶Does the calculator change the original number?
No. It reports a rounded representation and the numeric difference while keeping the entered value visible.
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Open calculator →Disclaimer: Rounding Calculator results are estimates for general information and education only, and are not financial, tax, legal or medical advice. Verify important decisions with a qualified professional.