How are negative numbers handled at a tie?

This mirrors JavaScript's native Math.round behavior: ties round toward positive infinity, so −0.5 rounds to 0, not −1.

What's the nearest-multiple mode useful for?

Rounding to a multiple like 5, 10, or 100 is common for pricing, bulk-order quantities, or rounding measurements to a practical increment.

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Math & Everyday

Rounding Calculator

Round to a decimal place, nearest integer, or nearest multiple — with a rounding mode you choose.

🔒 Runs entirely in your browser — nothing here is ever uploaded

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About the Rounding Calculator

Rounds a number to a chosen precision — nearest integer, a specific number of decimal places, or the nearest multiple of any number — using round-half-up, floor, or ceiling.

100% Free Runs in Your Browser No Sign-Up Required

How to use it

Enter your number.
Choose what to round to: decimal places, nearest integer, or nearest multiple of N.
Pick a rounding mode — round half up, round down (floor), or round up (ceiling).
Read the rounded result.

Formula

Decimal rounding shifts the decimal point via the number's own string representation before rounding, avoiding binary floating-point errors; nearest-multiple rounding divides by N, rounds, then multiplies back by N.

Worked example

1.005 rounded to 2 decimal places with round-half-up gives 1.01 — a naive Math.round(1.005*100)/100 in JavaScript would incorrectly give 1.00, since 1.005 can't be stored exactly in binary.

Recommendations

• Round down (floor) is useful when you must not exceed a value, like how many full boxes fit.
• Round up (ceiling) is useful when you must cover a full amount, like how many delivery trucks are needed.
• Rounding to the nearest multiple (like nearest 5 or 100) is common for pricing or bulk quantities.

Frequently asked questions

1.005 can't be stored exactly in binary floating-point — it's actually stored as slightly less than 1.005, so a naive Math.round(value*100)/100 mis-rounds it down. This tool shifts the decimal point via the number's text representation instead, which avoids that error.