How to use this calculator
- Pick one of the four modes at the top.
- Type your numbers — results update instantly, no button needed.
- The change mode colors increases green and decreases red.
The formulas
X% of Y = X÷100×Y; Share = Part÷Whole×100%; Change = (New−Old)÷|Old|×100%
Percent change uses the absolute initial value as its base, so going from −50 to −40 is a 20% improvement.
Frequently asked questions
How do I compute a discount?
Use the increase/decrease mode: enter the original price and −20 for a 20% discount, or compute 20% of the price and subtract it.
Does +10% followed by −10% cancel out?
No. 100 up 10% is 110; 110 down 10% is 99. Percent changes use different bases, so equal up-and-down moves net a loss.
What is the gain from 50 to 75?
(75−50)÷50 = +50%. But falling from 75 to 50 is (50−75)÷75 ≈ −33.3% — gains and losses are not symmetric.
Are negative numbers supported?
Yes — losses, negative rates, and negative starting values all work.
Disclaimer Results are for reference only and do not constitute financial, tax, or legal advice. Actual rates, returns, and fees depend on the terms of your financial institution.