The degree to which a given quantity is correct and free from error. For example, a quantity specified as has an (absolute) accuracy of (meaning its true value can fall in the range 99-101), while a quantity specified as has a (relative) accuracy of (meaning its true value can fall in the range 98-102).

The concepts of accuracy and precision are both closely related and often confused. While the accuracy of a number is given by the number of significant decimal (or other) digits
*to the right* of the decimal point in , the precision of is the total number of significant decimal (or other) digits.