Percentage calculation: basics and formulas
The three most common percentage tasks
The percentage calculation comes up everywhere – when shopping, filing taxes, at work, and when comparing prices. The word percent comes from the Latin "per centum", meaning "per hundred". A percentage therefore states how many parts out of 100 are meant. The base value (G) is the starting value, the percentage rate (p%) describes the share, and the percentage value (P) is the result. The three formulas are: P = G × p% ÷ 100, p% = P ÷ G × 100 and G = P ÷ p% × 100.
In everyday life, percentage calculations are especially relevant when shopping: a 30% discount on an item priced at €120 saves €36 – the final price is €84. VAT is also a percentage calculation: a net amount of €100 is increased by 19% VAT to €119 gross. For this, choose the "X% of Y" mode and enter 19 and 100.
The percentage change is essential when comparing figures over time: if a salary rises from €3,000 to €3,300, the increase is (3,300 − 3,000) ÷ 3,000 × 100 = 10%. If a share price falls from €50 to €40, the result is (40 − 50) ÷ 50 × 100 = −20%. Positive values mean an increase, negative values a decrease. Our calculator shows you not only the percentage but also the absolute difference.
The percentage share answers the question: "What percentage is X of Y?" If 21 out of 30 students in a class solved a task, that corresponds to 21 ÷ 30 × 100 = 70%. Use this mode for exam results, market shares, survey results, and anywhere you want to express a partial value in relation to a whole.