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Rounding Calculator: Decimal Places, Sig Figs and Nearest 10

This free rounding calculator rounds a number to a set number of decimal places, significant figures, or to the nearest 5, 10, 100 or 1000. It also shows the floor, ceiling and truncated value.

By Debmedia Technologies LLP · Kolkata, India · Updated

What Is It and When Do You Need It?

Rounding replaces a number with a nearby simpler one. You round prices to the nearest rupee, measurements to the precision of the ruler, and large figures to the nearest thousand. Different jobs need different kinds of rounding.

This tool offers the three most used kinds and also shows the floor, ceiling and truncation, which helps in programming and tax rules.

How to Use This Tool

  1. Type the number.
  2. Choose decimal places, significant figures or nearest multiple.
  3. Enter how many places or figures, or the multiple, such as 10.
  4. Press Calculate.

How the Calculation Works

For decimal places d, the number is multiplied by 10^d, rounded half up, then divided by 10^d. For significant figures, the tool finds the position of the first non-zero digit and rounds at that depth. For a multiple k, it rounds the number divided by k to a whole number and multiplies back.

Halves round away from zero, so 2.5 becomes 3 and −2.5 becomes −3.

Worked Example

Round 3.14159 to 2 decimal places: 3.14. To 3 significant figures: 3.14. Round 1,847 to the nearest 100: 1,800. Round 1,847 to the nearest 50: 1,850.

Common Uses

  • Prices, tax and invoices.
  • Lab reports with a set precision.
  • Making large numbers easy to read.
  • Programming checks for floor and ceiling.

Tips and Common Mistakes

  • Round only at the end of a calculation, not between steps.
  • Do not round 5 twice: round from the original number.
  • Money is normally rounded to two decimal places.

Next, you may need the scientific notation converter, percentage calculator, average calculator, fraction calculator.

Everything runs in your browser. Nothing you type is uploaded, stored or sent to any outside service.

Frequently Asked Questions

Look at the first digit you will drop. If it is 5 or more, round up; if it is 4 or less, round down. This is called round half up.
They are the meaningful digits of a number, counted from the first non-zero digit. 0.004560 has four significant figures: 4, 5, 6 and 0.
Choose Nearest multiple and enter 10 or 100. Use 5 to round to the nearest five, or 0.5 for the nearest half.
Floor goes down to the next whole number, ceiling goes up, and truncate simply drops the decimals, so for negative numbers the results differ.

Disclaimer: results are calculated in your browser from the numbers you enter. Check important results before you rely on them for money, health, safety or legal decisions.