Rounding to significant figures calculator
The Rounding to significant figures calculator computes rounding to significant figures from the relation round x to k sig figs. It takes 2 inputs (x, significant figures) and returns the rounded. Because this is a pure mathematical or physical formula rather than a jurisdiction-specific rule, the result never changes over time: the same inputs always produce the same answer, so you can rely on it whether you are checking homework, sizing a design, or sanity-checking another tool. Enter your values in the fields below and the result updates instantly; you can also share a permalink that pre-fills the exact calculation, which is useful for teaching, reports, or collaboration. For example, with x = 12345, significant figures = 2, the rounded works out to 12000, and the worked example further down the page shows every step so you can follow the arithmetic and reproduce it by hand. The method is the standard form documented by Documented methodology, and the figure above each result carries the date it was last verified. This tool is general information and is not a substitute for professional engineering, medical, financial, or scientific advice; always check critical results against the primary source and your own judgement.
With x = 12345, Significant figures = 2, the result is 12000.
Applies to: any numeric inputs. Method source: Documented methodology, checked 2026-06-23.
The formula
round x to k sig figs
Worked example
With x = 12345, Significant figures = 2:
- round to 2 sig figs
- Rounded = 12000
This worked example is one of the automated golden-value tests this calculator must pass before it can publish.
What this assumes
- Inputs are real numbers in the units shown.
- The result is the exact value of round x to k sig figs; general information, not professional advice.
Frequently asked questions
What formula does this use?
round x to k sig figs, the standard form documented by Documented methodology.
Does the result ever change over time?
No. This is a pure formula with no external rate, so the same inputs always give the same result.
Official sources and verification
- Method: Documented methodology, checked 2026-06-23.
Reviewed by the CalculatorHub team, edited by James Graham, 2026-06-23. See our methodology. General information, not professional advice.