Skip to content
Courses

Percent change

Percent change says how much a number moved relative to where it started: (new − old) ÷ old × 100. If sales go from $80K to $100K, they're up 25%.

Select any words here to ask your Maestro about them.

Sales go up 50% in March and down 50% in April. Where do you think they end up?

A store's sales, in thousands of dollars. Example data.

How to calculate it: (new − old) ÷ old × 100. If sales go from $80K to $100K, (100 − 80) ÷ 80 = 0.25: they're up 25%. If the result is negative, they went down. It's the same math for a percent increase, a growth rate or a percent decrease.

The starting point matters. 100 to 80 is −20%, but 80 to 100 is +25%. And a 50% rise followed by a 50% drop doesn't bring you back to where you started, as in the figure. If you compare several months against a base month, use it as the old value every time: (month − base) ÷ base.

When the number that changed is already a percentage, say whether you mean percentage points (the difference) or percent (the relative change). And when the old value is tiny, a huge percent change can be just a few units: give the count too.

Practice it in If something goes up 50% and then down 50%, are you back where you started? and Did it go up 2% or 2 points?.

How it's used

The formula in Excel

September vs. October

  1. Old: $80K (September). New: $100K (October).
  2. marked: (100 − 80) ÷ 80 = 0.25 → 25%Always divide by the old value: it's the starting point.
  3. In Excel: =(C2-B2)/B2 with percent formatB2 is the earlier month and C2 the new one.
  4. If the old value can be 0: =IF(B2=0,"",(C2-B2)/B2)From 0 to 5 there's no percent change: there's no starting point to measure from.
New minus old, over old. Flip the order and the number changes: 100 to 80 is −20%, but 80 to 100 is +25%.

When to look closer

Up 2%, or up 2 points?

The store's conversion rate

  1. September: 10% of visitors bought something.
  2. October: 12% of visitors bought something.

Conversion went from 10% to 12%. Is that up 2%, or up 2 points?

Ask your Maestro about Percent change

It answers from the free course page closest to this word, the way it answers while you study.

Example

You: What does "Percent change" mean, in plain words?

Your Maestro: I'll explain it with a case of yours: it sticks better than a definition. Which month do you compare your numbers against when you report?

Asking about: Answers from the page "If something goes up 50% and then down 50%, are you back where you started?"

Only this browser keeps what you ask here. How it works

Learn more

Related terms

  • Percentage

    A percentage says how many parts out of every 100 something is. You get it by dividing the part by the total and multiplying by 100: 45 out of 180 customers is 45 ÷ 180 × 100 = 25%.

  • KPI (key performance indicator)

    A KPI is a number a team tracks to know whether it's doing well at what matters most, like monthly sales or orders delivered on time. It only works if it's well defined, so two people who calculate it get the same answer.

  • Log scale

    A log scale is an axis where each equal step multiplies the value instead of adding to it, so 1,000, 10,000 and 100,000 sit evenly spaced.

The whole glossary