Rounding Calculator

Whether you're rounding to the nearest dollar, tenths place, or significant figure, this calculator handles all rounding scenarios instantly — with the correct rule applied every time.

How to Use This Calculator

1. Enter the number to be rounded.
2. Select the rounding place: nearest whole number, tenth, hundredth, thousandth, ten, hundred, thousand, or significant figures.
3. Click Calculate to see the rounded result and the rounding rule applied.

Rounding Rules

• Look at the digit immediately to the right of your target place.
• If it's 0–4: round down (keep the target digit the same).
• If it's 5–9: round up (increase the target digit by 1).

Example Calculations

• 3.74 rounded to tenths: look at 4 → round down → 3.7
• 3.75 rounded to tenths: look at 5 → round up → 3.8
• 2,847 rounded to hundreds: look at 4 → round down → 2,800
• 2,864 rounded to hundreds: look at 6 → round up → 2,900
• 0.00456 to 2 sig figs: 0.0046

Rounding vs. Truncating

Rounding considers the next digit and may round up or down. Truncating simply drops all digits after the target place — always rounds toward zero. 3.79 truncated to tenths = 3.7 (not 3.8).

Banker's Rounding (Round Half to Even)

When the digit to the right is exactly 5, banker's rounding rounds to the nearest even digit: 2.5 → 2, 3.5 → 4, 4.5 → 4, 5.5 → 6. This reduces cumulative bias in large datasets and is used in financial and scientific computing.

Common Mistakes to Avoid

• Rounding multiple times in sequence — Round only once to your target place. Sequential rounding accumulates error: 2.449 → 2.45 → 2.5 is wrong; 2.449 rounded to tenths is 2.4.
• Forgetting trailing zeros matter — 3.70 and 3.7 are equal numerically, but 3.70 indicates precision to hundredths. Context matters for significant figures.
• Confusing significant figures with decimal places — 0.00456 has 3 significant figures but 5 decimal places.

Frequently Asked Questions

What are significant figures?

Significant figures (sig figs) are the meaningful digits in a measurement. All non-zero digits are significant; zeros between non-zero digits are significant; trailing zeros after a decimal point are significant. Leading zeros are not.

How do I round a negative number?

Round the absolute value normally, then restore the negative sign. −3.75 rounded to tenths = −3.8 (round away from zero) under standard rules.

When do I need to round in everyday life?

Estimating bills, tax calculations, sports statistics, measurement in construction, financial reporting, and scientific results all require appropriate rounding to communicate meaningful precision.

Conclusion

Rounding is about communicating the right level of precision for your context. Use this calculator to round any number to any place value — correctly, every time.

Related: Percent Calculator | Scientific Notation Calculator | Standard Deviation Calculator