Enter any two fields and leave the third blank. First Number is the starting value; Second Number is the ending value. Percentage Change is the signed change from first to second: positive for growth, negative for a decrease. If all three fields are filled, the page reports the change from the two numbers.
Change (%) = (Second − First) ÷ First × 100Second = First × (1 + Change ÷ 100)First = Second ÷ (1 + Change ÷ 100)
The separate “First as % of Second” result is First ÷ Second × 100. Its denominator is the second number; the change formula uses the first number. Change is undefined when First is zero, and “% of Second” is undefined when Second is zero. Solving for First at −100% is also undefined. The calculator may display Infinity or NaN for these cases. Percentages can exceed 100%.
First = 100, Second = 120, Change blank → 20.00% change and 83.33% of Second. First = 100 and Change = −20 → Second = 80.
Calculator help v1.0