Percentage Decrease Calculator UK

Work out the percentage decrease between two values or apply a decrease to a number to find the reduced amount. Enter your figures and the calculator shows the answer with the working, so you can see exactly how it got there.

The Percentage Decrease Formula

To find how much something has fallen in percentage terms:

Percentage decrease = ((original − new) ÷ original) × 100

Always divide by the original value, not the new one. That is the single most common error with this calculation.

Working example: a jacket drops from £120 to £90. The decrease is £30, so (30 ÷ 120) × 100 = 25%. The price fell by 25%.

If your answer comes out negative, the value actually increases. A change from £80 to £92 gives (80 − 92) ÷ 80 × 100 = −15%, meaning a 15% rise.

Applying a Decrease to a Number

If you know the percentage and want the reduced value, multiply by (1 − rate as a decimal):

Decreased value = original × (1 − percentage ÷ 100)

Decrease £200 by 12%: 200 × 0.88 = £176 in one step. This multiplier method is quicker than finding 12% and subtracting, and it is the approach GCSE exam boards reward.

Everyday UK Examples

• Sale prices: 30% off a £65 pair of trainers: 65 × 0.7 = £45.50. You can also calculate discounts with our Percentage Off Calculator UK.
• Car depreciation: A car bought for £24,000 now worth £15,600 has lost (8,400 ÷ 24,000) × 100 = 35% of its value. Try our Car Depreciation Calculator.
• Energy usage: Cutting a bill from £180 a month to £153 is a 15% reduction.
• Weight loss: Going from 90kg to 81kg is a 10% decrease of starting body weight. Check calorie targets using the Calorie Deficit Calculator.
• Pay and hours: Dropping from a 40 hour week to 32 hours is a 20% reduction, the standard four day week cut. Check post-tax impact with our Salary Calculator UK.

Why a Decrease Is Harder to Undo Than You Think

Percentage changes are not symmetrical, and this asymmetry costs people real money.

If a £100 investment falls 50% to £50, a 50% rise only takes it back to £75. Recovering the full £100 needs a 100% gain. The general rule: after a fall of X%, the recovery required is X ÷ (100 − X) × 100. A 20% drop needs a 25% rise to break even and a 75% collapse needs a 300% recovery.

The same logic warns against adding successive decreases. A 20% discount followed by an extra 10% off is not 30% off. The reductions compound: £200 × 0.8 × 0.9 = £144, which is 28% off. Retailers rely on shoppers rounding that up.

Percentage Decrease vs Percentage Points

If a mortgage rate falls from 5% to 4%, that is a drop of 1 percentage point but a 20% decrease in relative terms. News reports mix these constantly. When the values you are comparing are themselves percentages, be explicit about which measure you mean.

If you need to reverse a percentage change, check out the Reverse Percentage Calculator UK or solve standard percentages with the Percentage Calculator UK.