Answer the percentage question - then understand what it means.
Calculate percentages, proportions, increases, decreases, reverse percentages and value adjustments from one complete workspace.
Start with the percentage question
Choose what you want to solve, then enter the two values involved.
The labels and result context adapt to the calculation type you choose.
Your performance snapshot
Start with the answer, then use the supporting metrics and working to understand the percentage relationship.
Choose a percentage question, enter two values and calculate.
Enter your numbers and calculate.
MPPM will explain the percentage relationship and the context behind it.
See the answer, the base and the working together.
A percentage can be misleading without its reference value. This breakdown keeps the absolute numbers beside the relative result.
Connect percentage changes to the wider business question.
MPPM Professional Services can help translate changes in price, cost, conversion, margin or growth into a practical commercial decision.
Turn one percentage answer into a repeatable decision workflow.
Free gives the complete standard percentage calculation. Pro adds connected planning and comparison workflows.
Scenario Lab
Compare percentage assumptions side by side.
Use the percentage result as evidence inside the MPPM workflow.
Decision Brief
Turn a percentage movement into a concise decision summary.
Use the percentage result as evidence inside the MPPM workflow.
Reverse & Target Planner
Work backwards from a target value or percentage.
Use the percentage result as evidence inside the MPPM workflow.
Reports & Export
Create a shareable calculation summary.
Use the percentage result as evidence inside the MPPM workflow.
Projects & Connected Calculators
Connect percentage results to a wider project.
Use the percentage result as evidence inside the MPPM workflow.
Unlimited History & Tracking
Keep revisions and percentage comparisons.
Use the percentage result as evidence inside the MPPM workflow.
A percentage only makes sense when you know what it is relative to.
Read the percentage together with the original value, absolute change and direction.
Identify the base
The denominator or original value determines what the percentage is relative to.
Check the absolute amount
A 10% movement can mean very different things on a base of 100 versus 1,000,000.
Keep direction clear
Percentage increases and decreases are asymmetric because the second change uses a different base.
How do percentage formulas change by question?
The same part-whole relationship can be rearranged depending on which value is unknown.
- X% of Y: X ÷ 100 × Y
- X is what % of Y: X ÷ Y × 100
- Percentage change: (New − Original) ÷ Original × 100
- Reverse percentage: Part ÷ (Percentage ÷ 100)
Keep working through the numbers.
Use the next calculator when the percentage belongs to a more specific decision.
A few things worth knowing before you judge the percentage.
What is a percentage?
A percentage expresses a part or proportion relative to 100, making differently sized quantities easier to compare.
How do I calculate X percent of Y?
Divide X by 100 and multiply the decimal by Y. For example, 20% of 500 is 0.20 × 500 = 100.
How do I calculate percentage increase or decrease?
Subtract the original value from the new value, divide the difference by the original value, then multiply by 100. A positive result is an increase and a negative result is a decrease.
Why does a 20% decrease followed by a 20% increase not return to the starting value?
The two percentages use different base values. After a decrease the new base is smaller, so the same percentage increase represents a smaller absolute amount.
What is the difference between percentage change and percentage-point change?
Percentage change measures relative movement from a base. Percentage points measure the direct difference between two percentages, such as 20% to 25% being a 5-point increase.
Can percentages be greater than 100% or negative?
Yes. More than 100% can describe a part larger than the reference whole or a large increase. Negative percentage change indicates a decrease under the standard change formula.