Home / Percentage Decrease Calculator

Percentage Decrease Calculator

By Cedrick Reese · Reviewed August 2026

Find out how much a value has gone down, expressed as a percentage of where it started. Enter the original value and the new, lower value below.

This percentage decrease calculator finds how much a value went down, expressed as a percentage of where it started. If you're not sure the value will always go down, use the Percentage Change Calculator instead. If you already know a discount percentage and want to work backward to the original price, use the Reverse Percentage Calculator.

Formula: Decrease % = ((Original − New) ÷ |Original|) × 100

Calculate percentage decrease

The starting number, before the decrease.

The ending number, after the decrease.

Percentage decrease

—

The percentage decrease formula

Percentage decrease uses the same formula as percentage change — it's simply the case where the result comes out negative, shown here as a positive drop:

Decrease % = ((Original − New) ÷ |Original|) × 100

Worked examples

A stock price moves from $100 to $75. What's the percentage decrease?

Decrease % = ((100 − 75) ÷ 100) × 100 = (25 ÷ 100) × 100 = 25%

Going the other way: applying a known percentage decrease

If you already know the percentage and want the resulting value, multiply the original number by (1 − percentage ÷ 100). A 20% decrease on 200 is 200 × 0.80 = 160.

Frequently asked questions

What if the result comes out negative?

A negative result means the value actually increased, not decreased. This calculator will tell you that directly and point you to the Percentage Change Calculator, which handles both directions without assuming a decrease.

How do I find the new value after a known percentage decrease?

Multiply the original number by (1 − percentage ÷ 100). A 20% decrease on 200 is 200 × 0.80 = 160. This is the reverse of what this calculator solves — here you're going from percentage back to a dollar or unit value.

Is percentage decrease the same as percentage change?

Percentage decrease is percentage change limited to the negative case, shown as a positive drop instead of a negative number. Both use the identical formula: ((Original − New) ÷ |Original|) × 100. If you're not sure the direction will always be downward, the Percentage Change Calculator handles either direction automatically.

I know the discounted price and the discount percentage — how do I find the original price?

That's a different problem from what this calculator solves. This page finds the percentage between two known values. To work backwards from a final price and a percentage to the original price, use the Reverse Percentage Calculator.

If something decreases 50%, does a 50% increase bring it back to where it started?

No — decrease and increase percentages aren't symmetric, because each one is calculated against a different base. $200 decreased by 50% is $100. Increasing $100 by 50% only gets you to $150, not back to $200 — you'd actually need a 100% increase to reverse a 50% decrease. The percentage is always relative to the current value, not the original.

Sources

Calculators

Percentage Change Calculator Find the percentage change between an old value and a new value. Percentage Increase Calculator Find how much a value went up, as a percentage of where it started. Percentage Difference Calculator Compare two values fairly when neither one is the original. Reverse Percentage Calculator Find the original value before a discount, tax, or increase was applied. Percent Off Calculator Find the sale price and dollar savings from a discount percentage.

Guides

How to Calculate Percentage Change: Step-by-Step Guide The four-step manual method, with worked examples including a negative starting value.

This calculator is provided for general informational purposes and is not financial, tax, or professional advice. Verify important decisions with a qualified professional.

Cedrick Reese, Founder

I'm Cedrick Reese, a retired veteran and web developer who built PercentageChangeCalculators.com as part of Ready Utilities, my collection of free, user-friendly online tools. My journey began in the early 2000s with affiliate marketing and niche site development, which grew into a passion for creating practical digital utilities and calculators. After retiring, I earned a Computer Systems Technician certificate from UEI College, completed Electro-Mechanical Technologies at Tulsa Welding School, and finished the Carpentry program at Florida State College at Jacksonville. Today, I combine my technical background and craftsmanship by building furniture using traditional woodworking methods, gardening, and developing helpful online tools for users worldwide.