Percentage calculator
Calculate proportions, changes and original amounts with visible formulas; your numbers are processed locally in your browser.
Ile to X% z Y?
X to jaki % z Y?
Zmiana procentowa
Napiwek / VAT / rabata
Średnia / liczba / dane
Netto / brutto / VAT
Choose the right percentage calculation
- Use the percentage calculator form that matches your question: a percentage of an amount, a share of a whole, or a change between values.
- Enter both numbers and check the base: the whole for a proportion, or the starting value for a change.
- Select increase or decrease when adjusting an amount or recovering its original value.
- Calculate, then inspect the formula with your numbers substituted to see which denominator was used.
- Choose up to 2, 4 or 6 decimal places, or use the extra boxes for tips, VAT and averages.
Everyday percentage problems
- Find a discount amount before subtracting it from the listed price.
- Express completed work as a percentage of the planned total.
- Recover a price from the amount paid after a reduction.
- Compare two non-negative measurements without choosing either as the baseline.
- Calculate an average alongside the minimum, maximum and sum of a list.
Percentages explained with examples
How do I find a percentage of a number or the whole?
15% of 200 is 0.15 × 200 = 30. Conversely, if 30 is 15% of an unknown whole, divide 30 by 0.15 to get 200.
How does percentage change differ from percentage difference?
Going from 100 to 120 is a 20% increase, using 100 as the base. The symmetric difference uses their average, 110, giving about 18.18%.
How do I reverse a discount?
If a price after a 20% reduction is 80, the original is 80 ÷ 0.8 = 100. Adding 20% to 80 would give only 96.
Are percentage points the same as percent?
A rate moving from 10% to 15% rises by 5 percentage points. Relative to the initial rate, that is a 50% increase.
What happens with zero or negative inputs?
A zero base makes relative change undefined. Negative starting values use their absolute value as the denominator. The symmetric difference form accepts only non-negative values.
How should I interpret rounding and VAT?
Precision controls displayed decimal places, not invoice rounding rules. For an illustrative 20% VAT rate, 100 net gives 20 VAT and 120 gross; enter the rate relevant to your calculation.