Number Rounding Calculator — Decimal Places & Significant Figures
Round numbers to a chosen number of decimal places (3.14159 → 3.14) or significant figures (0.00012345 → 0.0001235) with half-up, half-even (banker), ceiling and floor rules — handles carry overflow like 9.999 → 10.00 and 9999 → 10000, live validation, recent 10 records, one-click copy and PNG download.
The rounded value will appear here with the chosen precision and rule.
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What is it
Rounding replaces a number with a nearby value at a chosen precision: decimal places count digits after the point, significant figures count all meaningful digits from the first non-zero one.
Notes & fun facts
When pricing goods, filling in lab reports or checking measurements, rounding to the right number of digits with the right rule keeps every figure accurate and consistent.
Origin & history
Rounding rules emerged with ancient measurement systems and currency handling, the classic practice being half-up rounding. To avoid systematic bias when many values are rounded repeatedly, modern computing adopted half-even (banker's) rounding and similar rules, gradually standardized through floating-point standards such as IEEE 754 — now a common convention in accounting, statistics and engineering.
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