Stacked changes

Up 50% then down 50% isn’t back to even.

Traffic dips 20% then recovers 20%. Are you back where you started? No. Percent changes multiply, they don’t add. That’s why a bad quarter takes more than one good quarter to recover from.

The move

Convert each change to a multiplier and multiply them: +10% → 1.1, −20% → 0.8. Then subtract 1 to get the net change.

Worked example

+50% then −50%

  1. 1.5 × 0.5 = 0.75
  2. 0.75 − 1 = −0.25
  3. Net: −25%
  • Two +10% months is +21%, not +20%. The extra 1% is growth on your growth.
  • Same % up then down always leaves you below where you started.