Four percentage calculators in one — find a percentage of a number, work out what percentage one number is of another, and calculate percentage change.
Multiply Y by X ÷ 100. Example: 15% of £280 = 280 × 0.15 = £42. Useful for: VAT amounts, discounts, commission, tips, pension contributions.
Divide X by Y and multiply by 100. Example: £42 of £280 = (42 ÷ 280) × 100 = 15%. Useful for: finding what proportion one number is of another — your tax rate, your savings rate, the deposit percentage on a house.
((New − Old) ÷ Old) × 100. Example: salary rising from £35,000 to £37,450 = ((37,450 − 35,000) ÷ 35,000) × 100 = 7%. A negative result means a decrease. Useful for: pay rises, investment returns, inflation comparisons.
Increase: multiply by (1 + rate/100). Decrease: multiply by (1 − rate/100). Example: £45,000 increased by 5.5% = £45,000 × 1.055 = £47,475. A 20% discount on £65 = £65 × 0.80 = £52.
Percentages are foundational to UK financial calculations — from interest rates to tax bands, from VAT to mortgage deposits, from inflation to investment returns. Understanding the four core percentage operations covers nearly all everyday needs: percentage OF a number ("what is 20% of £150?" → £30), one number AS a percentage of another ("what percentage is £30 of £150?" → 20%), increase/decrease BY a percentage ("£150 increased by 20%" → £180), and reverse-percentage ("what was the original price before 20% VAT?" → £150 / 1.20 = £125).
The most common UK financial percentage applications: VAT calculations (20% standard rate, 5% reduced rate, 0% zero rate) — to ADD VAT to a £100 net price, multiply by 1.20 (£120); to STRIP VAT from a £120 gross price, divide by 1.20 (£100). Income tax bracket math — 20% basic, 40% higher, 45% additional rates applied to specific income slices. Mortgage Loan-to-Value (LTV) calculation — £200,000 mortgage on a £250,000 property = 80% LTV. Compound interest projections — £10,000 at 5%/year for 10 years = £10,000 × (1.05)^10 = £16,289.
Practical UK examples requiring percentage math: pay rise calculations ("a 4% pay rise on £30,000 = £1,200 extra/year, but real-terms loss if inflation is 5%"); pension contribution sizing ("5% workplace pension on £40,000 = £2,000/year gross"); SDLT band calculations ("5% on the £75,000 between £250,000 and £325,000 = £3,750"); credit-card APR understanding (a 22% APR on a £1,000 balance carried for a year = £220 of interest, compound monthly = slightly more). Even savings: a 4.5% AER on £20,000 means £900/year if interest is taken annually, or slightly more with monthly compounding.
Common percentage pitfalls: "100% increase" doubles a number, "200% increase" triples it (the increase IS the multiplier, not the result). A 50% decrease followed by a 50% increase doesn't restore the original — £100 falling 50% to £50 then rising 50% reaches only £75. Percentage differences vs percentage point differences matter: tax rising from 20% to 22% is a 2 percentage-point increase but a 10% relative increase. These distinctions matter for mortgage rates, pension projections, and financial reporting.
This page performs arithmetic only. It contains no statutory rates or thresholds of its own, so there is nothing here to cite. Checked on 2 September 2026.
UKCalc assumptions — not official figures
Percentage points versus percent. A rate moving from 20% to 22% is a rise of two percentage points, but a 10% relative increase. Financial reporting frequently conflates the two.