Rounding Calculator
Quickly round numbers to decimal places, significant figures, nearest 10/100/1000, up/down, or to an integer. Free tool with instant results and support for local number formats (commas, periods, spaces).
Number format
Choose how numeric results are displayed. The selected decimal separator (dot or comma) will also be used when parsing input numbers.
Rounding Calculator helps you round any number to the precision you need—decimal places, significant figures, nearest integer, tens, hundreds, and more. It's handy for reports, invoices, measurements, grade averages, or anytime you want clean numbers that are easy to read and compare.
At its core, rounding replaces a number with a nearby value that has fewer digits. The key is to choose a rule (round half up, round half to even, up/ceiling, down/floor) and a target precision (decimal places or significant figures).
How to use this tool
- Enter a number (supports negatives and scientific notation like
3.27e5). - Choose a precision:
- Decimal places (e.g., 0, 1, 2, 3…)
- Significant figures (e.g., 1–10+)
- Nearest unit (ones, tens, hundreds, thousands)
- Select a rounding rule:
- Nearest (half up): 0.5 goes up (common in everyday use)
- Nearest (banker's / half to even): 0.5 rounds to the nearest even digit (reduces bias in totals)
- Round up (ceiling): toward +∞
- Round down (floor): toward −∞
- Truncate: simply cut off extra digits (no rounding)
- Click Calculate to get your rounded value. You'll also see the difference from original to understand impact.
Tip: If you're preparing published numbers or aggregations (averages, totals), consider banker's rounding (half to even) to avoid upward bias.
Rounding basics (what changes and why)
- Decimal places: Count digits after the decimal point. Rounding to 2 decimals makes prices like
12.345become12.35. - Significant figures: Keep meaningful digits regardless of decimal point position. Useful for measurements and scientific data.
- Nearest unit (tens, hundreds…): Helpful for estimates and summaries (e.g., population ≈
23,000).
Ties (…5 cases): When the first dropped digit is exactly 5 with nothing nonzero after it, a tie occurs:
- Half up: 2.5 → 3; 3.5 → 4
- Half to even (banker's): 2.5 → 2 (even); 3.5 → 4 (even)
Examples you can follow
Everyday prices (decimal places)
12.994 to 2 decimals (half up) → 12.99
12.995 to 2 decimals (half up) → 13.00
12.995 to 2 decimals (half to even) → 13.00
Measurements (significant figures)
0.004567 to 2 sig figs → 0.0046
15678 to 3 sig figs → 15,700
Nearest unit
2,348 to nearest hundred (half up) → 2,300
2,550 to nearest hundred (half to even) → 2,600
Negative numbers
-2.3 floor → -3; -2.3 ceiling → -2
Quick reference
| Original | 0 dp | 1 dp | 2 dp | 3 dp |
|---|---|---|---|---|
| 12.994 | 13 | 13.0 | 12.99 | 12.994 |
| 12.995 | 13 | 13.0 | 13.00 | 12.995 |
| 2.5 | 3 | 2.5 | 2.50 | 2.500 |
| -2.5 | -2 | -2.5 | -2.50 | -2.500 |
| Original | Nearest 10 | Nearest 100 | Nearest 1,000 |
|---|---|---|---|
| 245 | 240 | 200 | 0 |
| 250 | 250 | 300 | 0 |
| 1,450 | 1,450 | 1,400 | 1,000 |
Significant figures in plain language
- Leading zeros don't count:
0.004560has four sig figs (4, 5, 6, 0). - Zeros between digits do count:
105has three sig figs. - Trailing zeros after a decimal count:
2.300has four sig figs. - Whole numbers without a decimal: trailing zeros may be ambiguous. Use scientific notation for clarity:
2.30 × 103→ three sig figs2.3 × 103→ two sig figs
Example: Round 0.004567 to 2 sig figs → 0.0046. Round 15678 to 3 sig figs → 15,700.
Tips for clean, consistent results
- Pick a rule and stick to it across a report or dataset (especially for tie cases).
- Round at the end of a multi-step calculation to avoid compounding error.
- Match significant figures to the precision of your measurement tools.
- Show units (m, kg, s, °C) with rounded values to keep context.
- Communicate your rule in documentation (e.g., “Rounded to 2 d.p., half to even”).
FAQ
Which rounding rule should I use?
For everyday numbers, Nearest (half up) is familiar. For finance, statistics, or large aggregates, Nearest (half to even) helps reduce cumulative bias.
What's the difference between decimal places and significant figures?
Decimal places count digits after the decimal point; significant figures count meaningful digits overall. Use decimal places for money and formatting; use significant figures for measurements and scientific data.
How does rounding affect totals and averages?
Rounding individual items and then summing can produce a different result than summing first and rounding once. For reports, compute totals first, then round the final values.
How are negative numbers handled?
Nearest rules work the same. For up/ceiling and down/floor, remember: up → toward +∞, down → toward −∞.
What is banker's rounding (half to even)?
On a tie (.5), the result goes to the nearest even last kept digit. This balances 0.5 cases and reduces bias across large datasets.
Does the calculator support scientific notation?
Yes. You can enter numbers like 6.022e23 or 3.5e-4. The output will follow the rounding rule you choose.
Should I round intermediate steps?
Avoid it when possible. Keep full precision during calculations and round at the end for the final presentation.
What about trailing zeros?
Trailing zeros are part of the format: 2.50 (two decimal places) conveys more precision than 2.5, even though the numeric value is the same.