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Free online rounding calculator to round numbers to any decimal place. Round to nearest, round up, or round down with step-by-step explanations and instant results.
Use 0 for whole numbers, negative for tens/hundreds (e.g., -1 for tens)
Rounding is a mathematical process of reducing the number of significant digits in a number while keeping its value close to the original. It simplifies numbers to make them easier to work with, understand, and communicate.
For example, rounding 3.14159 to 2 decimal places gives 3.14, and rounding 47.8 to the nearest ten gives 50.
Round 3.7 to nearest whole number:
Look at 7 (first decimal) → 7 ≥ 5 → Round up → 4
Round 3.4 to nearest whole number:
Look at 4 (first decimal) → 4 < 5 → Round down → 3
Round 3.456 to 2 decimal places:
Look at 6 (third decimal) → 6 ≥ 5 → Round up → 3.46
The most common method. Uses the 5 rule: if the next digit is ≥5, round up; if <5, round down.
Examples:
3.5 → 4 (5 rounds up)
3.4 → 3 (4 rounds down)
3.456 to 2 decimals → 3.46 (6≥5, round up)
3.453 to 2 decimals → 3.45 (3<5, round down)
Always rounds to the next higher value, regardless of the following digits. Useful when you need to ensure you have enough.
Examples:
3.1 → 4 (always up)
3.9 → 4 (always up)
3.01 to 1 decimal → 3.1 (always up)
Use case: Buying materials (need at least this much)
Always rounds to the next lower value, regardless of the following digits. Useful when you can't exceed a limit.
Examples:
3.9 → 3 (always down)
3.1 → 3 (always down)
3.99 to 1 decimal → 3.9 (always down)
Use case: Budget limits (can't spend more than this)
Decimal places indicate how many digits appear after the decimal point. You can also round to positions left of the decimal (tens, hundreds, etc.) using negative decimal places.
Round to 2 decimal places for cents. Example: $12.456 → $12.46. Used in prices, taxes, interest calculations, and financial reports.
Round averages, percentages, and data for clarity. Example: Average score 87.456 → 87.5 or 87. Makes data easier to read and present.
Round to appropriate precision. Example: Length 12.3456 cm → 12.35 cm. Match precision to measuring instrument accuracy.
Use significant figures. Example: 0.004567 to 3 sig figs → 0.00457. Maintains appropriate precision in calculations and results.
Round to specification tolerances. Example: 12.3456 mm → 12.35 mm. Critical for manufacturing and construction accuracy.
Round large numbers for readability. Example: 1,234,567 → 1.23 million. Makes reports cleaner and easier to understand.
Keep full precision during calculations. Round only the final answer to avoid accumulating errors.
Money needs 2 decimals, measurements vary by instrument, scientific work may need more precision.
Standard rounding for most cases, round up for safety margins, round down for limits.
Don't round intermediate steps. Each rounding introduces error that compounds.
For large datasets, use round-half-to-even to reduce cumulative bias from 0.5 cases.
In reports, specify rounding method and precision used for transparency and reproducibility.
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Comprehensive lessons on rounding with practice problems and video tutorials
Visit Khan Academy →Mathematical definitions and properties of rounding methods with advanced concepts
Visit MathWorld →Easy-to-understand explanations with examples and interactive demonstrations
Visit Math is Fun →Official guidelines for rounding in scientific and technical applications
Visit NIST →Round to nearest, round up (ceiling), or round down (floor) - more options than basic calculators.
Round to tens, hundreds, thousands using negative decimal places - unique feature for large numbers.
See exactly how the rounding was calculated with clear explanations of the method used.
One-click access to common examples (π, decimals, whole numbers) for faster learning.
12 detailed FAQs covering all aspects of rounding, from basics to advanced topics like banker's rounding.
Learn how rounding is used in money, statistics, measurements, science, and engineering.
Learn when and how to round properly to avoid errors and maintain accuracy.
Visual guide showing positive and negative decimal places with clear examples.
Built-in reference showing common rounding examples for quick lookup.
Learn about truncating vs rounding, significant figures, banker's rounding, and negative numbers.
Lightning-fast calculations with immediate display of rounded values.
No ads, no sign-up, no limitations. Completely free with unlimited calculations.