Rounding Calculator

Modify the values and click the Calculate button to use

Rounded: 6

Original number: 5.51
Precision: 0 decimal places
Mode: nearest
Rounded: 6

Different rounding modes treat halfway values differently. Use the mode required by your calculation or reporting standard.

What this rounding calculator does

Rounding replaces a number with a nearby value that has fewer digits. This calculator rounds to a chosen number of decimal places using one of several rounding modes.

Different fields use different conventions. “Nearest” is common in everyday use; “half-even” is often used in statistics and finance to avoid upward bias.

How to use this calculator

Enter the number.
Enter the number of decimal places (0–20).
Choose a rounding mode.
Click Calculate.

The default example rounds 5.51 to 0 decimal places using the nearest-half-up rule, producing 6.

Rounding rules

Nearest (half up): round 5 and above up, 4 and below down.
Up: always round away from zero.
Down: always round toward zero.
Ceiling: round toward positive infinity.
Floor: round toward negative infinity.
Half to even: halfway values go to the nearest even digit.

What the results mean

The rounded value is displayed with the requested number of decimal places. For example, 5.51 rounded to 0 places is 6, and 5.49 is 5. Negative values follow the selected mode.

Assumptions and limitations

The calculator works with decimal numbers and a non-negative precision from 0 to 20. It does not model significant figures, currency-specific rounding, or binary floating-point behavior.

Some modes, such as half-away-from-zero and half-toward-zero, are not included in this version. Use the mode required by your reporting standard.

Frequently asked questions

What is the difference between rounding up and ceiling?

“Up” rounds away from zero, so −5.1 becomes −6. “Ceiling” rounds toward positive infinity, so −5.1 becomes −5.

Why use half-even rounding?

It reduces cumulative bias when many halfway values are rounded. It is common in statistical and financial calculations.

Does rounding change the original value?

No. Rounding produces a new displayed value. Keep the original number if you need full precision.

How many decimal places can I choose?

From 0 to 20. Very high precision may exceed the display precision of standard floating-point numbers.

Source

Reference: Wolfram MathWorld — Rounding.

Disclaimer

This calculator is for educational purposes. Follow the rounding convention required by your course, employer, or reporting standard.

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