Capital gains tax, calculated with the working shown.

Enter a gain, get the tax, and see every step of the arithmetic, the allowance applied, your basic rate band split, the rate on each slice. Correct figures for each tax year back to 2021 to 2022, including the mid-year rate change of 30 October 2024 that most calculators ignore. Everything runs on this page, nothing you type goes anywhere.

The working
Enter your figures and the working appears here.

Assumes an individual with the standard personal allowance, assets other than residential property, no reliefs, and current frozen income tax thresholds. For 2024 to 2025 the allowance and losses are set against post-October gains first, the ordering HMRC permits and the one that favours you. An estimate for orientation, not a filing document.

This was the easy part.

Every calculator on the internet, including this one, asks you to already know your gain. The actual work of crypto tax is computing that gain, matching every disposal under same day, 30 day and section 104 pooling rules across every wallet and exchange you have ever used. The full app does exactly that, on your machine, with the rule named on every disposal, free below 1,000 transactions.

Compute my actual gains

Calculator questions.

How is UK capital gains tax calculated on crypto and shares
Net gains for the tax year, minus the annual exempt amount (£3,000 currently), are taxed at 18% where they fit inside your unused basic rate band and 24% above it. Older years used different allowances and rates, and this calculator carries the correct historic figures per year.
Is this calculator accurate for my actual tax return
It computes the tax on a gain you already know, using the correct year figures. The genuinely hard part of crypto tax is computing the gain itself under the matching rules, same day, 30 day, then section 104 pooling, which is what the full app does, free below 1,000 transactions.
Does this calculator send my numbers anywhere
No. It runs entirely on this page in your browser. Nothing you type is transmitted, stored or logged, which you can verify in your browser network tab.
What happened to capital gains tax rates on 30 October 2024
Rates on assets other than residential property rose from 10% and 20% to 18% and 24% from 30 October 2024, mid tax year, so 2024 to 2025 disposals are taxed under two regimes depending on their date. The calculator handles the split.

Figures verified 21 August 2026 against HMRC's published allowances, rates, historic rates and allowances and income tax bands. General information, not personal tax advice, see a vetted professional for your own affairs.