Percentage Decrease Calculator — Find % Drop Between Two Numbers

Percentage decrease measures how much a value has fallen, relative to where it started. It answers questions like "the price dropped from ₹2,000 to ₹1,500 — what percentage discount is that?" or "attendance fell from 90 students to 72 — by what percentage?"

Just like percentage increase, this is always calculated against the original (starting) value, not the new one — a drop from 100 to 50 is a 50% decrease, but a drop from 50 back down to 25 is also 50%, even though the actual numbers involved are different.

Formula

Percentage Decrease = ((Old Value − New Value) ÷ Old Value) × 100

This always gives a positive number when the value has genuinely gone down.

Worked Example

Worked example

Question: A jacket's price drops from ₹2,000 to ₹1,500. What is the percentage decrease?

Step 1 — Find the difference: ₹2,000 − ₹1,500 = ₹500

Step 2 — Divide by the old value: ₹500 ÷ ₹2,000 = 0.25

Step 3 — Convert to a percentage: 0.25 × 100 = 25%

Answer: The price decreased by 25% — that is the discount rate.

Discounts are percentage decreases

Every "% off" sale tag is a percentage decrease calculation in reverse — the shop decides the decrease first (say 30% off) and works out the new price from there. If you know both prices and want to check the advertised discount is accurate, this calculator confirms it in one step.

Decreases larger than 100%?

A percentage decrease can never realistically exceed 100% for a positive value dropping to zero — a decrease of exactly 100% means the new value is 0. If your calculation shows more than 100%, double check the new value is not negative or that the old and new values have not been swapped.

Frequently Asked Questions

What is the formula for percentage decrease?

Subtract the new value from the old value, divide by the old value, then multiply by 100: ((Old − New) ÷ Old) × 100.

How do I check a shop's advertised discount is correct?

Enter the original price as the old value and the sale price as the new value — the result should match the advertised discount percentage.

What does 100% decrease mean?

A 100% decrease means the value has dropped all the way to zero.

Can I use this for exam score drops or attendance drops?

Yes — any two comparable numbers work, whether that is price, attendance, marks, revenue, or population.

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