📚 Percentage change calculators
The change percentage cluster compares two measurements over time or across methods: signed percent change, one-direction increase or decrease, symmetric difference, and error against a reference. Each tool states which value is the denominator.
Use this hub when the story is movement between two values: growth, contraction, signed change, or symmetric difference. Pick increase or decrease when direction is fixed; use signed change when the outcome can be negative.
Key facts
| Percent increase | ((new − original) ÷ original) × 100 when original is the baseline. |
|---|---|
| Use cases | KPI deltas, price moves, lab error, A/B metric shifts. |
| Category | Analytics / measurement |
| Related concepts | Percentage points, successive change, reverse percentage. |
Definitions
Percent increase
New minus original, divided by original, times 100—original must be nonzero.
Percent difference
Symmetric comparison of two values without forcing a single baseline.
Formulas
- Increase %: ((new − original) / original) × 100
- Decrease %: ((original − new) / original) × 100
- Percent error: |measured − true| / |true| × 100
Comparison table
| Topic | Guidance |
|---|---|
| Increase vs signed change | Increase assumes growth framing; signed change allows negative outcomes. |
| Difference vs change | Difference is often symmetric; change picks a baseline denominator. |
❓ Frequently Asked Questions
Which baseline should I use?
Use the original or reference value as the denominator unless your policy specifies otherwise.
Where is year-over-year change?
Use percentage change or increase with prior-period and current values as original and new.
Glossary references
Reinforce entities by pairing percent language with conversion pages when learners mix fractions, decimals, and ratios.