Rounding Calculator Online
Round any number to decimal places, significant figures, or the nearest multiple, with four rounding methods, right in your browser.
The Rounding Calculator runs entirely in your browser. Numbers you enter are computed locally and never leave your device.
Open the Scientific Notation Calculator
About Rounding Calculator
The Rounding Calculator rounds any number three different ways: to a fixed number of decimal places, to a count of significant figures, or to the nearest multiple of any value you choose, such as 5, 10, or 0.25. Pick a rounding method to control how exact halfway values are handled — round half up (the everyday rule), round half to even (banker's rounding, used to reduce bias in repeated calculations), always round down, or always round up. Type a number, choose a mode, and the result updates instantly along with a short worked summary you can copy. It is useful for homework, unit price comparisons, lab measurements with a fixed number of significant figures, and cash or quantity totals that need to land on a round multiple. Everything runs locally in your browser — no numbers are uploaded.
Features
- Round to a fixed number of decimal places, including negative places for tens and hundreds
- Round to a chosen count of significant figures for scientific or lab-style precision
- Round to the nearest multiple of any value, such as 5, 25, or 0.1
- Four rounding methods: half up, half to even (banker's rounding), floor, and ceiling
- Instant result as you type, with a worked summary line
- Copy button for the rounded value
- Handles negative numbers correctly in every mode and method
- Runs entirely in your browser with no numbers sent anywhere
How to use the Rounding Calculator
- Type the number you want to round
- Choose decimal places, significant figures, or nearest multiple
- Enter the places or the multiple to round to
- Pick a rounding method and read the rounded value
Example
Input
3.14159 to 2 dp
Output
3.14
Common errors & troubleshooting
- Significant figures result looks the same as decimal places. — Significant figures count all meaningful digits from the first nonzero digit, while decimal places only count digits after the decimal point — switch modes to see the difference, especially for numbers over 1000.
- Rounding to the nearest multiple gives an unexpected value. — Check the 'Nearest multiple of' field — rounding 13 to the nearest 5 gives 15, not 10, because 13 is closer to 15.
- A value ending in exactly .5 doesn't round the way I expected. — Half up always rounds .5 away from zero, while half to even (banker's rounding) rounds .5 to whichever neighbor is even — switch the rounding method to match what you need.
- Rounding down or up seems reversed for negative numbers. — Floor always rounds toward negative infinity and ceiling always rounds toward positive infinity, so floor on -2.1 gives -3, not -2.
Frequently asked questions
- What rounding methods does the Rounding Calculator support?
- It supports half up (the everyday rounding rule, ties away from zero), half to even (banker's rounding, ties go to the nearest even digit), floor (always round down), and ceiling (always round up).
- What is the difference between decimal places and significant figures in this calculator?
- Decimal places count digits after the decimal point only. Significant figures count all meaningful digits starting from the first nonzero digit, so 12345 rounded to 2 significant figures is 12000, while 12345 rounded to 2 decimal places is still 12345.
- How does the Rounding Calculator round to the nearest multiple?
- Enter any value in 'Nearest multiple of' — such as 5, 10, or 0.25 — and the calculator finds the closest multiple of that number, using the rounding method you selected to break exact ties.
- What is banker's rounding and why would I use it?
- Banker's rounding (half to even) rounds an exact .5 to whichever neighboring number is even, instead of always rounding up. It is used in finance and statistics because it avoids the small upward bias that half-up rounding introduces over many repeated calculations.
- Can the Rounding Calculator round negative numbers?
- Yes. All three modes and all four rounding methods work correctly with negative numbers — floor and ceiling behave directionally (toward negative or positive infinity), which matters most for negative values.
- Are the numbers I enter in the Rounding Calculator sent anywhere?
- No. The Rounding Calculator computes every result locally in your browser. The numbers you type never leave your device and are not uploaded to ArrayKit.
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