Finance guide
How to Solve Common Percentage Calculations
Calculate a percentage of a value, percentage change, discounts, markups, and reverse percentages.
Identify the base value
“What is 20% of 50?” uses 50 as the base. “20 is what percent of 50?” divides the part by that base. Writing the relationship before entering values prevents many swapped-input errors.
Distinguish change from percentage points
A move from 20% to 25% is five percentage points, but it is a 25% relative increase. For percentage change, subtract the old value, divide by the old value, and multiply by 100.
Check edge cases
A zero starting value makes ordinary percentage-change division undefined. Negative bases also require context. Keep enough precision during the calculation and round only the final displayed result.