Percentage Decrease Calculator
Find exactly how much — in percentage terms — a value has fallen from its original level.
About the Percentage Decrease Calculator
Knowing by how much something fell is just as important as knowing it went down at all. The Percentage Decrease Calculator quantifies that drop in universally understood percentage terms.
The Formula
Percentage Decrease = ((Original Value − New Value) / Original Value) × 100
Example: A laptop was $1,200 and is now on sale for $900. Decrease = ((1200 − 900) / 1200) × 100 = 25%.
Practical Applications
Retail pricing: Black Friday deals advertised as "40% off" use this exact formula. Verify advertised discounts by plugging original and sale prices into this tool.
Weight loss tracking: Started at 220 lb and now weigh 198 lb? That's a 10% decrease — a meaningful milestone tracked by many health programs.
Business costs: Operating expenses fell from $85,000 to $71,400 after process improvements — a 16% reduction worth reporting to stakeholders.
Energy use: Monthly electricity consumption dropped from 900 kWh to 720 kWh after installing solar panels — a 20% decrease in consumption.
Percentage Decrease vs. Percentage Off
These terms mean the same thing. "20% off" a $50 item means the price decreases by 20%, saving you $10. The new price is $40.
Reverse Calculation: Finding the Original
If you know the decreased value and the percentage decrease, find the original: Original = New Value / (1 − Decrease%/100). A product now costs $68 after a 15% markdown — the original price was 68 / 0.85 = $80.
Avoiding Confusion with Negative Percentages
When using generic percentage-change tools, a negative result signals a decrease. Always confirm which direction change occurred before reporting results in business dashboards or academic papers.