Three common percentage questions, answered instantly.
Solve common percentage questions while keeping the base value and direction clear—two details that cause many everyday mistakes.
Best for: Discounts, growth rates, markups, score changes and “what percent is X of Y?” calculations.
A percentage is always relative to a base. Increasing 100 by 20% gives 120, but decreasing 120 by 20% gives 96—not 100—because the second percentage uses a different base.
Implements common percentage formulas directly in JavaScript and reports the arithmetic result. The most important input is the correct base/reference value.
Use domain-specific formulas for finance, statistics or tax where the definition of the percentage is governed by rules.
This section describes the implementation shipped with My Tools HQ. Verify important outputs before relying on them.
Got a different result? Report a problem with Percentage Calculator. Include your browser, steps and expected result. Please do not send sensitive files.
The second change is applied to a different base value.
It is the arithmetic difference between two percentages: 10% to 15% is +5 percentage points but a 50% relative increase.
Usually the original or reference value, depending on the question being asked.
Avoid the base-value mistakes behind discounts, growth rates and percentage-point confusion.