Rounding Calculator

How to Use the Rounding Calculator

Enter a number

Type any number, including decimals — for example 3.14159.

Set decimal places and significant figures

Choose how many decimal places and how many significant figures you want. Both results are shown at once, along with the nearest integer, 5, 10, 100, and 1000.

Pick a rounding mode

Choose half-up (the everyday default), half-down, or banker's rounding (half-to-even), which statisticians and accountants use to avoid bias.

Read all the results

Every rounding is shown together so you can pick the one you need, and switching modes updates them instantly.

Rounding, Done Properly

More Than One Way to Round

Rounding sounds trivial until you realise there are several distinct kinds, and most online calculators only do one of them. The most familiar is rounding to a number of decimal places — turning 3.14159 into 3.14. But scientists and engineers far more often need significant figures, which count meaningful digits from the first non-zero one: 0.0045678 to two significant figures is 0.0046, and 12,345 to three is 12,300. Significant figures matter because they communicate precision honestly — saying a measurement is "0.0046" tells the reader exactly how confident you are, in a way "0.00" never could. This calculator does both, side by side, and adds the everyday "round to the nearest 5, 10, 100, or 1000" that you need for estimates, pricing, and headcounts. Seeing them together makes the differences obvious and keeps you from reaching for the wrong kind.

There is also the question of how to handle the exact halfway case — and here, again, there is more than one correct answer. The schoolroom default is "round half up": 2.5 becomes 3. But that rule has a subtle bias, because it always pushes halves upward, which over many roundings can inflate a total. Statisticians and accountants therefore often use "banker's rounding", or round-half-to-even: 2.5 rounds to 2 and 3.5 rounds to 4, sending halves to the nearest even number so that, on average, the rounding errors cancel out. It is the default in many financial systems and scientific standards for exactly this reason. This calculator lets you choose between half-up, half-down, and banker's rounding, so you can match whatever convention your work requires — and see immediately how the choice changes the answer for a tricky value.

"Rounding is not one rule but a family of them. Decimal places, significant figures, and how you break a tie are three separate choices — and getting them right is the difference between honest numbers and misleading ones."

Where It Matters

Precise rounding is quietly important across a lot of work. In science labs, reporting a result to the correct number of significant figures is a basic requirement — too many digits overstates precision, too few throws information away. In finance and accounting, the choice of rounding rule affects reconciliations and can, at scale, move real money, which is why banker's rounding is so common there. In engineering and manufacturing, rounding to the nearest practical increment (the nearest millimetre, the nearest 5) turns an exact calculation into something you can actually build. And in everyday life, rounding to the nearest 10 or 100 is how we make numbers graspable. Because this tool shows every kind of rounding at once, with selectable tie-breaking, it suits all of these uses from one page — and because it runs entirely in your browser, your numbers never leave your device.

10 Facts About Rounding

01

Decimal places count digits after the point; significant figures count meaningful digits.

02

0.0045678 to 2 significant figures is 0.0046 — leading zeros do not count.

03

"Round half up" is the schoolroom default: 2.5 → 3.

04

Banker's rounding sends halves to the nearest even number: 2.5 → 2, 3.5 → 4.

05

Banker's rounding removes the upward bias that always rounding up creates.

06

It is the default in many financial systems and the IEEE floating-point standard.

07

Significant figures honestly communicate the precision of a measurement.

08

Rounding 12,345 to 3 significant figures gives 12,300.

09

"Round to nearest 5/10/100" is how we make numbers easy to grasp.

10

This tool shows every kind of rounding at once, with selectable tie-breaking.

Frequently Asked Questions

Decimal places count digits after the decimal point, so 3.14159 to two decimal places is 3.14. Significant figures count meaningful digits starting from the first non-zero one, so 0.0045678 to two significant figures is 0.0046. Scientists usually need significant figures; everyday rounding usually means decimal places. This calculator shows both at once.
Banker's rounding (round half to even) rounds an exact halfway value to the nearest even number — so 2.5 becomes 2 and 3.5 becomes 4. This avoids the slight upward bias of always rounding halves up, which is why it is the default in many financial systems and the IEEE floating-point standard. Select it with the "Banker's" mode.
Set the "significant figures" box to how many you want and read off the result. The calculator counts from the first non-zero digit, so leading zeros in small numbers do not count, and it pads or trims trailing digits as needed. For example 12,345 to three significant figures is 12,300.
Because 2.675 cannot be stored exactly in binary floating point — it is actually a hair below 2.675 — so naive code rounds it down. This calculator compensates for that floating-point quirk so that values like 2.675 and 1.005 round the way you expect (to 2.68 and 1.01).
Yes — the results include the nearest integer, 5, 10, 100, and 1000 automatically, using whichever tie-breaking mode you have selected. This is handy for estimates, pricing to the nearest five, and making large counts easy to read.
Half-down rounds an exact halfway value toward zero (2.5 becomes 2). It is less common than half-up or banker's rounding but is occasionally required by specific accounting or regulatory rules. The mode is there for when you need to match such a convention exactly.
Yes. Negative numbers are rounded by the same rules applied to their magnitude, with the sign preserved. The results panel shows the rounded negative value for each option just as it does for positives.
Because different fields care about different things. Everyday life uses round-half-up for simplicity; finance and science use banker's rounding to avoid cumulative bias; some regulations specify half-down. There is no single "correct" rule — the right one depends on context, which is why the calculator lets you choose.
Yes. All rounding happens in your browser — nothing is uploaded, stored, or logged — and it works offline once loaded.
Completely free, with no account, sign-up, or limit. It runs entirely in your browser and collects no data. Use it as often as you like.

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