Percentage Change Calculator — Growth, Drop, Points & Reverse

Real-world use cases

• Report quarter-over-quarter revenue growth in an earnings deck

  Q1 revenue was $4.2M, Q2 came in at $4.83M. Drop both into Old to New and you get +15% — the signed, color-coded number that goes on the growth slide. The Difference stat also shows the raw +$0.63M so you can put the absolute dollars in the footnote. Because the denominator is locked to the OLD quarter, this matches how every board deck and analyst model defines QoQ growth, so nobody on the finance team re-derives it and gets a different figure.

• Translate a stock or crypto move into a clean percentage

  A position opened at 318 and is now at 271. Old to New returns -14.78% in red with a down arrow, plus the -47 absolute delta. The color and sign mean you read the direction at a glance instead of squinting at whether 271/318 is above or below 1. Copy the sentence straight into your trade journal. Switch decimals to 2 for the report, or 0 when you just want the headline number.

• Set and check a KPI target without fooling yourself

  Support tickets resolved within SLA sat at 82%, the OKR says push it to 90%. Percentage points tells you that is +8 percentage points, while the relative bump is only +9.76%. Knowing it is 8 points, not "8 percent", keeps the goal honest in the all-hands. Then use Old plus rate to sanity-check: 82 plus an 8-point move is the target, but an 8% relative move would land you at just 88.6%, short of goal.

• Sanity-check a "everything must go" price cut

  A $59 item is marked down to $39. A vs B (A = 39, B = 59) reports -33.9%, the real discount off the original. But you also want to know the markup needed to get back to $59 later: feed 39 and 59 the other way and you see +51.3%, the reverse direction. The asymmetry between -33.9% down and +51.3% back up is exactly the +50%/-50% trap, made concrete with your own prices.

• Grade a before/after experiment for a class or a blog post

  A landing page converted at 2.4%, the redesign converts at 3.1%. Percentage points shows +0.7 pp, and the relative change shows a far punchier +29.2%. Both are true, and the mode prints them together so your write-up can lead with the +29% headline while the footnote keeps the honest +0.7-point figure. The copy button gives you the full sentence to paste into the post, citing this tool as the source.

Common pitfalls

• Dividing by the new value instead of the old one. Growth and price moves always divide by the STARTING value. From 150 to 180, divide by 150 to get +20%, not by 180 (which would wrongly give +16.7%). This tool locks the denominator to the old value in Old-to-New so you cannot pick the wrong one.

• Saying "percent" when you mean "percentage points". A rate moving 5% to 8% rose 3 percentage points, not "3 percent". Reporters and PMs say "3 percent" and it sounds like a tiny +0.15-point nudge instead of the real +60% relative jump. Always name the unit. The Percentage points mode shows both numbers so you label it correctly.

• Assuming a +X% then -X% cancels out. It never does, because the second percentage is taken on a different, usually larger, base. +50% then -50% lands you at 75% of where you started, not 100%. To undo a +50% gain you need a -33.3% cut. Verify any round trip in Old-plus-rate before you quote it.

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