About this calculator
Significant figures describe the precision expressed by a written number, not simply how many decimal places it contains. In 0.00450 the leading zeros locate the decimal point; the digits 4, 5 and the final zero express three significant figures. Enter the number exactly as recorded so the tool can preserve zeros that a normal numeric input would discard.
A whole number such as 1200 does not unambiguously state whether its final zeros were measured. The tool identifies this ambiguity rather than asserting four significant figures. Write 1.2 × 10³ as 1.2e3 for two significant figures, or 1.200e3 for four. An explicit decimal point in 1200. states that those trailing zeros count. Zero measurements require a convention and are explained separately.
The rounding mode retains the requested number of significant digits and uses scientific notation to make trailing-zero precision explicit. Halfway values round away from zero. Use the Rounding Calculator for decimal-place rounding, the Scientific Notation Calculator to work with powers of ten, or the Percent Error Calculator to compare a measurement with a reference value.
Frequently asked questions
How many significant figures does 1200 have?
Without a decimal point or stated measurement precision, the trailing zeros are ambiguous. It has at least two significant figures and may represent up to four. Scientific notation makes the intention explicit.
Are zeros after a decimal point always significant?
Only after the first nonzero digit. The zeros at the beginning of 0.00450 are placeholders, while its final zero is significant.
Why use scientific notation for rounded results?
It preserves the requested precision unambiguously. For example, 1.00e3 explicitly has three significant figures, unlike a bare 1000.