Rounding Calculator
Round a number to any decimal place or whole-number magnitude.
Try an example
3,847.26
About this calculator
What Is Rounding?
Rounding replaces a number with a nearby one that is shorter, simpler or easier to work with, while staying close to the original value. 2.7 rounds to 3 at the nearest whole number, and 1,482 rounds to 1,500 at the nearest hundred. People round to make results readable — prices, measurements, statistics — and to match the precision of the data they started with. This rounding calculator lets you choose the place value (ones, tenths, hundreds, and so on) and the rounding method.
Common Rounding Methods
- Round half up: a value exactly halfway between two choices goes to the higher one (2.5 → 3). This is the rule most people learn in school.
- Round half down: a halfway value goes to the lower one (2.5 → 2).
- Round up (ceiling): always moves to the next higher value, even for 2.1 → 3.
- Round down (floor): always moves to the next lower value, so 2.9 → 2.
- Round half to even (banker's rounding): a halfway value goes to the nearest even number (2.5 → 2, 3.5 → 4). Because ties are split evenly between up and down, it avoids a systematic upward bias across many roundings, which is why it is used in finance and computing.
- Round half away from zero: halfway values move away from zero, so −2.5 → −3.
The treatment of negative numbers is where methods differ most, so check which convention your task requires.
Worked Example
47.863 rounded to 2 decimal places is 47.86, since the digit after the hundredths place (3) is less than 5.
How to Round by Hand
Find the digit in the place you are rounding to, then look at the digit just to its right. If that digit is 5 or more, increase the target digit by 1; if it is 4 or less, leave it alone. Drop (or zero out) everything after. For example, rounding 3.14159 to two decimal places looks at the 1 after the 4, so the answer is 3.14.
Rounding vs. Significant Figures
Rounding to a place value fixes the decimal position, while significant figures count meaningful digits from the first non-zero digit. Both reduce precision on purpose; pick the one that fits your field. For arithmetic with rounded results, the Basic Calculator is one click away.
Worked example
3,847.2591 rounded to 2 decimal places is 3,847.26 — the digit right after the cutoff (9) rounds the last kept digit up.
Frequently asked questions
What rounding rule does this use?
"Round half up": if the digit right after your chosen place is 5 or more, the last kept digit rounds up; otherwise it stays the same.
Can I round to the nearest ten, hundred, or thousand?
Yes — choose a negative decimal place (e.g., nearest 100) instead of a positive one.
Why does rounding matter for calculations?
Rounding too early in a multi-step calculation can compound small errors — it's usually best to round only the final result.
Does rounding always round up on a 5?
With this calculator's "round half up" rule, yes — some other systems use "round half to even" (banker's rounding), which can round a 5 down instead.
