Percentage Decrease Calculator — Loss, Drop, & Decline Math
Calculate how much a value has decreased, expressed as a percentage. Perfect for tracking weight loss, investment drops, and price reductions.
How It Works
Percentage decrease = ((old - new) ÷ old) × 100. Example: $100 → $85 = (15 ÷ 100) × 100 = 15% decrease.
Weight loss: Losing 10 lbs from 200 lbs is (10 ÷ 200) × 100 = 5% weight loss.
A stock falling from $50 to $35 lost (15 ÷ 50) × 100 = 30%. To break even, it needs to rise ~43% — illustrating why drawdowns are brutal.
Expense reduction uses the same formula: cutting $500/month expenses from a $5,000 budget = 10% reduction.
Frequently Asked Questions
How do I calculate percentage decrease?
(old - new) ÷ old × 100. Example: 200 → 160 = (40/200) × 100 = 20% decrease.
What's the difference between percent and percentage points?
Percent is proportional change; percentage points are absolute differences. Going from 5% to 7% interest is a 2 percentage point increase but a 40% percent increase.
If a stock drops 50% then rises 50%, am I back to even?
No — you're down 25%. $100 → $50 → $75. This is the asymmetric nature of losses: you need a 100% gain to recover a 50% loss.