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About the Percentage Change Calculator
A simple, free percentage change calculator for marketers running period-over-period (PoP), year-over-year (YoY), or week-over-week (WoW) reporting. Enter two numbers, get the percentage change and absolute delta. Handles negatives, zero baselines, and decimals cleanly.
How to use
- Enter your starting value (old number).
- Enter your ending value (new number).
- Read the percentage change and absolute delta instantly.
Common use cases
- Campaign performance reporting (open rate change week-over-week)
- Revenue / MRR growth
- Retention cohort deltas
- A/B test uplift quick checks
Who it's for
Marketers, analysts, and operators who need a fast, reliable way to calculate percentage change without opening a spreadsheet.
Frequently asked questions
- How do you calculate percentage change?
- Percentage change = ((new value − old value) / |old value|) × 100. A positive result is growth; negative is decline.
- What happens when the starting value is zero?
- Percentage change from zero is mathematically undefined. The tool shows the absolute change and flags that the percentage is undefined.
- Is this the same as percentage point change?
- No. Percentage point change is used when both values are already percentages (e.g. conversion rate went from 2% to 3% = +1 percentage point, +50% relative change).
Related Orbit tools
Built into Orbit for Claude
Want this built into your reporting? Orbit does it natively.
Inside Orbit for Claude, percentage change is wired into every performance pull. Ask Claude to report on a campaign or Canvas and it calculates PoP, YoY, and WoW deltas automatically, with the right denominators and correct handling of zeros and small samples.