🎯 Significant Figures Calculator
0.004560 has 4 significant figures — and this calculator shows you exactly which digits count and why, digit by digit, then rounds to any precision you need.
4
significant figures
0.0046
rounded to 2 sig figs
Digit-by-digit
0.004560
green significantgrey leading zero (placeholder)amber ambiguous trailing zero
Leading zeros are placeholders, never significant.
Other roundings (exact arithmetic)
The rules applied
- Non-zero digits are always significant.
- Zeros between non-zero digits are significant (105 has three).
- Leading zeros never are — they only place the decimal point (0.004560 starts counting at the 4).
- Trailing zeros are significant only with a decimal point (100.0 has four; 1200 is ambiguous — use scientific notation to be explicit).
Counting and rounding are done on the digit string itself — no floating-point re-formatting to corrupt the answer. Runs locally.
How the significant figures calculator works
The calculator applies the sig-fig rules to the digit string itself and shows the classification per digit: non-zero digits always count; zeros between non-zero digits count (105 has three); leading zeros never count — they only place the decimal point; trailing zeros count only when there's a decimal point (100.0 has four), and in a bare integer like 1200 they're flagged amber as ambiguous, with the standard advice to use scientific notation to say what you mean. Rounding to N significant figures happens on the digits too — including the carry case where 9.99 rounded to two sig figs correctly becomes 10 — so no floating-point re-formatting ever corrupts the result.
The ambiguity flag is the honest part most calculators skip: "1200" genuinely doesn't say whether those zeros were measured, and chemistry teachers dock marks for pretending otherwise. Writing 1.2×10³ (two sig figs) or 1.200×10³ (four) settles it — which is why this tool pairs naturally with the scientific-notation converter.
Frequently asked questions
What are the significant figure rules?
Non-zero digits always count. Zeros between non-zero digits count. Leading zeros never count. Trailing zeros count only if there's a decimal point — in a bare integer they're ambiguous. The calculator color-codes every digit by exactly these rules.
How many sig figs does 1200 have?
Two unambiguous ones (1 and 2) — the trailing zeros are ambiguous without more context. Write 1.2×10³ for two sig figs or 1.200×10³ for four; the tool flags this case explicitly.
How do I round to N significant figures?
Keep the first N significant digits, look at the next one: 5 or more rounds up. Watch the carry case — 9.99 to 2 sig figs is 10, not 9.9. The tool handles the carry on the digit string exactly.
Why do sig figs matter?
They encode measurement precision: a length of 2.0 cm claims more certainty than 2 cm. Calculations shouldn't claim more precision than their inputs — the reason sig-fig rounding exists in every science course.
Is anything computed in floating point?
No — counting and rounding operate on the digit characters, so 30-digit numbers work exactly. Runs locally.