Mathematics · Basics
Rounding Calculator — Decimal Places, Significant Figures & Nearest Multiple
Round any number exactly — no floating-point slips like 1.005 becoming 1.00. Choose decimal places, significant figures, or the nearest multiple (nearest 10, 1,000, 0.5 or 0.05), and the rounding rule: school half-up, banker's half-to-even, ceiling, floor or truncate.
Your inputs
Quick start — try a typical case
Decimal places can be negative: −2 rounds to the nearest hundred.
Your result Live
Rounded
1,234.57
1,234.5678 to 2 decimal places — half up
- Change
- +0.0022
- Indian Grouping
- 1,234.57
- Scientific Notation
- 1.23457 × 10³
- Significant Figures in the Input
- 8
How this is calculated
Look at the first digit to be dropped: 5 or more rounds up (half up); exactly 5 rounds to the even neighbour (banker's)
- Multiple m
- Rounded = m × round(x ÷ m)
To round, keep the digits you want and look at the next one. Under the usual school rule 5 or more rounds up. Banker's rounding sends an exact half to the even neighbour so that, over many values, ups and downs balance — it's used in accounting and by many programming languages. Significant figures count from the first non-zero digit, so 0.004561 to 2 significant figures is 0.0046.
Assumptions & sources
- Calculations are exact on the decimal digits you type — there's no binary floating-point error.
- 1Mathematics, Classes 6–11 — Number systems, exponents, sequences and series — NCERT
- 2IEEE 754 rounding (round half to even) — IEEE Standard for Floating-Point Arithmetic
Calculator ID MATH-ROUND-001 · version 1.0.0
Common questions
What is 1.005 rounded to 2 decimal places?
1.01 by the half-up rule (1.00 under banker's rounding). Many calculators wrongly give 1.00 because of floating-point storage; this one works on the exact digits.
How do I round to the nearest 100?
Choose 'Nearest multiple' and enter 100, or use −2 decimal places. 1,234.5 → 1,200.
What are significant figures?
The digits from the first non-zero digit onward. 0.004561 has 4; rounded to 2 it's 0.0046.