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Percentage Calculator
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Percentage Decrease Calculator

Find out how far a value has fallen in percentage terms. Enter the original and the new value, and the calculator shows the size of the drop and how it was worked out.

What is the percentage decrease?

Enter your numbers and press Calculate — the full working appears here.

The percentage decrease formula

A decrease is measured against the value you started with, exactly like an increase — the only difference is the direction of travel.

((Original − New) ÷ Original) × 100

((200 − 150) ÷ 200) × 100 = 25%

Written this way the answer comes out positive, which is how a decrease is normally quoted — “a 25% decrease”, not “a −25% change”.

Worked example: an energy bill

Your monthly energy bill falls from $180 to $126 after you switch tariff. How big is the saving in percentage terms?

  1. Find the size of the fall.180 − 126 = 54
  2. Divide it by the original bill.54 ÷ 180 = 0.3
  3. Multiply by 100.0.3 × 100 = 30%

Answer30% decrease

Open this example in the calculator →

When you need a percentage decrease

  • Price cuts — how much a reduced price has actually come down, independent of the advertised claim.
  • Cost savings — the effect of switching supplier, renegotiating a contract or cutting a subscription.
  • Falling demand — sales, bookings or sign-ups against a previous period.
  • Usage reductions — energy, fuel or data consumption after a change of habit.
  • Depreciation — the drop in a vehicle or device's value since purchase.

If you are shopping rather than analysing, the discount calculator is the more direct tool — it gives you the money off and the price you pay rather than a percentage.

Frequently asked questions

How do I calculate percentage decrease?
Subtract the new value from the original, divide by the original, then multiply by 100. Going from 200 to 150: 200 − 150 = 50, then 50 ÷ 200 = 0.25, then 0.25 × 100 = 25%.
What is the percentage decrease from 200 to 150?
25%. The value fell by 50, and 50 is a quarter of the original 200.
How do I subtract a percentage from a number?
Multiply by 1 minus the percentage as a decimal. To take 20% off 200, multiply 200 × 0.8 = 160. That single step replaces working out the reduction and subtracting it.
Can a percentage decrease be more than 100%?
Only if the value crosses below zero. A fall of 100% means the value reached zero, so anything beyond that implies a negative result — a debt rather than a balance, for example.
Why is a 50% rise not cancelled out by a 50% fall?
Because each percentage is measured against a different starting point. £100 rising 50% gives £150; 50% of £150 is £75, leaving you at £75 rather than back at £100. Reversing a 50% rise takes a 33.3% fall.

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