Need to round a number to a specific number of decimal places? The rounding calculator handles standard rounding plus ceiling, floor, and half-down methods - all with real-time results as you type.
Rounding Calculator
Using the rounding calculator
Enter your number in the Number field and choose how many decimal places you want in the Decimal places field. The result updates instantly as you type!
Optionally, elect your rounding method with the buttons:
- Half Up - Standard rounding you learned in school. Values at exactly .5 round up.
- Half Down - Like standard rounding, but .5 values round down instead.
- Ceiling - Always rounds up toward positive infinity.
- Floor - Always rounds down toward negative infinity.
Rounding methods explained
Most people only know one rounding method, but there are actually several - and they matter when you're dealing with financial calculations, statistics, or programming.
Half up (standard rounding)
This is what you learned in school: if the next digit is 5 or higher, round up. Otherwise, round down.
- 2.5 → 3
- 2.4 → 2
- -2.5 → -2 (rounds toward positive infinity)
Half down
Same as half up, except ties go down instead of up. Used in some statistical applications to reduce upward bias.
- 2.5 → 2
- 2.6 → 3
- -2.5 → -3
Ceiling
Always rounds up toward positive infinity. Any fractional part pushes the number up.
- 2.1 → 3
- 2.9 → 3
- -2.1 → -2 (toward positive infinity, so less negative)
Floor
Always rounds down toward negative infinity. The opposite of ceiling.
- 2.9 → 2
- 2.1 → 2
- -2.1 → -3 (toward negative infinity, so more negative)
When to use each method
Half up works for most everyday purposes - it's what people expect when they hear "rounding."
Ceiling is useful when you need to ensure you have enough of something - like calculating how many boxes you need to ship 47 items when each box holds 10.
Floor works when you can only use whole units and can't exceed a limit - like calculating how many complete batches you can make with available ingredients.
Half down and banker's rounding (half to even) are used in financial and statistical contexts to minimize cumulative rounding bias over many calculations.
