Free Rounding Calculator Online
This free online rounding calculator rounds numbers to any decimal place, significant figure, or whole number position with multiple rounding modes.
Rounding Input
Use negative for tens (-1), hundreds (-2), etc.
Rounded Result
Enter a number above
How the Rounding Calculator Works
The rounding calculator takes a number and rounds it to the precision you specify. Choose decimal places (0 for whole number, 1 for tenths, 2 for hundredths, etc.) or significant figures. The rounding calculator supports standard rounding, floor, and ceiling modes.
Standard rounding: 3.456 rounded to 2 decimal places = 3.46 (the 6 rounds the 5 up). 3.454 rounds to 3.45 (the 4 stays). The rounding calculator handles all these cases automatically.
The rounding calculator also shows all common rounded forms simultaneously — to ones, tenths, hundredths, thousandths, and significant figures — so you can compare at a glance. Use negative places to round to tens (−1), hundreds (−2), or thousands (−3).
Rounding Rules
Standard (Half Up)
5–9 round up, 0–4 round down. Most common method. The rounding calculator uses this by default.
Floor
Always round toward negative infinity. 3.7 → 3, −3.2 → −4. The rounding calculator applies floor consistently.
Ceiling
Always round toward positive infinity. 3.2 → 4, −3.7 → −3. The rounding calculator applies ceiling consistently.
Significant Figures
Count meaningful digits from the first non-zero. The rounding calculator supports 1–10 significant figures.
Tips for Using the Rounding Calculator
Choose the Right Precision
For money, use 2 decimal places. For scientific data, use significant figures. The rounding calculator handles both.
Negative Places for Large Numbers
Use −1 for tens, −2 for hundreds. 1234 rounded to −2 = 1200. The rounding calculator supports this notation.
Floor vs Ceiling
Use floor to always round down (conservative estimates). Use ceiling to always round up (safe margins). The rounding calculator shows both.
All Forms at Once
The rounding calculator shows the number rounded to multiple precisions simultaneously for quick comparison.
Frequently Asked Questions
More Math Calculators
Percentage Calculator
Calculate percentages, percent change, and percent of a number.
Percent Change Calculator
Calculate the percentage change between two values — increase or decrease.
Percentage Increase Calculator
Calculate the percentage increase from one value to another.
Fraction Calculator
Add, subtract, multiply, and divide fractions instantly.