Percentage Change Calculator

Quick answer: Percentage Change Calculator is a free online tool that lets you measure growth or decline between two values. Enter the old and new numbers to get the percentage change, the absolute difference and a clear increase/decrease label. It works instantly with no signup or download — everything runs privately in your browser.

Measure growth or decline between two values. Enter the old and new numbers to get the percentage change, the absolute difference and a clear increase/decrease label.

What is the Percentage Change Calculator?

A percentage change calculator answers one of the most-asked quantitative questions: how much did something go up or down, in relative terms? The formula is (New − Old) / Old × 100. A positive result is an increase, a negative result is a decrease, and the absolute difference shows the raw size of the move.

Relative change is far more informative than raw difference — a $10 rise matters enormously on a $20 item and barely at all on a $2,000 one. This free percentage change calculator is used for prices, salaries, investments, web traffic, test scores and anywhere else ‘up by how much, really?’ needs a precise answer.

Context turns a percentage change from trivia into insight. A 200% jump in website traffic means little if the baseline was ten visitors, while a 2% dip in a billion-dollar revenue line is a $20 million event — which is why the calculator shows the absolute difference alongside the percent. Use both numbers together in reports, and always name the baseline period so readers can judge the move fairly and avoid being misled by cherry-picked baselines.

How to use the Percentage Change Calculator

  1. Enter the old (starting) value — the baseline you are comparing against.
  2. Enter the new (current) value you want to measure.
  3. Click Calculate to see the percentage change and the absolute difference.
  4. Check the increase/decrease label to confirm the direction of the move.
  5. Swap the values to analyze the reverse change if needed.

Percentage Change Calculator use cases

Investment performance

Track portfolio or stock moves precisely: a rise from $45 to $58 is a 28.9% gain. Percentage change lets you compare winners and losers fairly regardless of share price, and it is the same math behind reported fund returns.

Price tracking

Verify inflation claims and sale hype. If rent went from $1,200 to $1,350, that is a 12.5% increase — knowing the exact figure strengthens negotiations and helps you spot when a ‘small’ increase is actually large.

Business KPIs

Month-over-month revenue, conversion rate and traffic changes are all reported as percentage change. Consistent measurement reveals trends that raw numbers hide, like a steady 3% monthly decline compounding into a serious problem.

Fitness progress

Measure weight loss, strength gains or pace improvements in relative terms. Dropping from 200 to 185 lbs is a 7.5% reduction — a motivating, standardized way to track progress across different metrics and body sizes.

Tips

  • The old value is the baseline — swapping old and new gives a different percentage.
  • A 50% drop needs a 100% gain to recover: losses and gains are asymmetric.
  • Chain multiple changes by multiplying, not adding, the percentages.
  • For informational purposes only — pair with absolute numbers for full context.

Frequently asked questions

What is the percentage change formula?
Percentage change = (New value minus Old value) divided by Old value, times 100. A positive result means an increase and a negative result means a decrease. For example, from 100 to 120: (20 / 100) x 100 = 25% increase. The old value is always the baseline — swapping old and new gives a different answer.
How do I calculate percentage increase?
Subtract the old value from the new value, divide the difference by the old value, and multiply by 100. A salary rising from $50,000 to $55,000 is (5,000 / 50,000) x 100 = 10% increase. This calculator does it instantly and also shows the absolute dollar difference alongside the percentage.
How do I calculate percentage decrease?
Use the same formula — the result will simply be negative. A price falling from $80 to $60 is (60 - 80) / 80 x 100 = -25%, i.e. a 25% decrease. The calculator labels decreases clearly so you never have to interpret a bare negative sign yourself.
Why does a 50% loss need a 100% gain to recover?
Because percentages apply to different baselines. If $100 drops 50% to $50, regaining $50 requires doubling — a 100% gain on the new $50 baseline. This asymmetry is why investors fear drawdowns: the deeper the loss, the disproportionately larger the recovery gain needed.
What if the old value is zero?
Percentage change from zero is undefined, because the formula divides by the old value. Going from 0 to any positive number is sometimes described informally as infinite growth, but it is more honest to report just the absolute change. The calculator flags this case instead of returning a misleading number.
Can I add two percentage changes together?
No — chained percentages multiply, they do not add. A 10% increase followed by a 10% decrease leaves you at 99% of the start (1.10 x 0.90 = 0.99), not back at 100%. For multi-step analysis, apply each change sequentially or compute (final / initial - 1) x 100 directly.
Percentage change vs. percentage points — which should I use?
Use percentage points when subtracting two percentages (15% minus 10% = 5 percentage points), and percentage change for the relative move (that same shift is a 50% relative increase). In reports and headlines, mixing them up is a classic error — this calculator's output is always the relative percentage change.