Capital Gains Tax Calculator
The Capital Gains Tax Calculator estimates how much tax you owe when you sell a capital asset — shares, property, cryptocurrency, or collectibles. It covers US federal capital gains tax rates (0%, 15%, and 20% long-term; ordinary income rates short-term) and UK Capital Gains Tax rates (10%/18% basic rate, 20%/24% higher rate) for the 2024-25 tax year.
Educational estimate. Calculator results are for planning and information only, not financial, tax, medical, legal, or engineering advice. Verify important decisions with official sources or a qualified professional.
Capital Gains Tax Calculator
US & UK Capital Gains Tax Estimator
📐 Formula & Method
Capital Gain
Your taxable capital gain is the proceeds from the sale minus your cost basis (purchase price) and any allowable selling costs.
US Long-Term Capital Gains Tax (2024)
For assets held over 1 year. These are 2024 rates for single filers. Net Investment Income Tax (NIIT) of 3.8% may apply for high earners.
UK Capital Gains Tax (2024-25 post-Budget)
UK CGT rates were changed in the October 2024 Autumn Budget. Non-property gains: 10% (basic rate) / 20% (higher rate). Residential property gains: 18% (basic rate) / 24% (higher rate). Annual CGT allowance is £3,000 for 2024-25.
📋 How to Use
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1
Enter the purchase price (cost basis) — the original price you paid including buying costs.
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2
Enter the sale price — what you received when you sold the asset.
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3
Enter any selling costs such as commissions, legal fees, or broker charges.
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4
Select your holding period and tax situation (US or UK).
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5
For US rates, select your income band to determine your applicable capital gains rate.
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6
Click Calculate to see your capital gain, estimated tax, and net proceeds.
💡 Key Insights
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In the US, holding an asset over 12 months drops your tax rate from ordinary income (up to 37%) to long-term CGT (0/15/20%) — usually a >15-point saving.
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The US 0% long-term CGT bracket extends to ~$47k single / ~$94k joint of taxable income (2024). Many early retirees realise gains tax-free here.
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UK CGT annual exemption fell from £12,300 → £6,000 → £3,000 (2024–25). The shrinking allowance makes ISA wrapping more valuable than ever.
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UK property CGT rates (18%/24%) are higher than non-property (10%/20%) and have no private residence relief unless it's your only home.
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Tax-loss harvesting lets US investors offset gains with realised losses — up to $3,000/year of ordinary income, with the excess carried forward.
🧮 Worked Examples
US long-term, mid bracket
Bought stock at $20,000, sold at $50,000, selling costs $1,000, single filer in 15% LT bracket.
UK higher-rate non-property
UK higher-rate taxpayer sells shares with £18,000 gain.
📊 How to Interpret Your Result
Gain offset by losses
No tax owed. Excess loss can offset other gains or up to $3,000 ordinary income (US).
Long-term US, 0% bracket
Realise as much gain as possible here — it's genuinely tax-free.
Short-term US gain
Taxed as ordinary income — up to 37% federally. Strongly consider waiting until 12 months to qualify for long-term rates.
UK higher-rate gain
Use Bed & ISA to shelter future gains. Spouses can split assets to use both annual exemptions.
⚠️ Common Mistakes to Avoid
Forgetting selling costs (brokerage fees, agent commissions).
Fix: These reduce your taxable gain dollar-for-dollar. Always include.
Mis-identifying holding period (US short vs long).
Fix: Long-term = held more than 365 days. Count from trade date, not settlement date.
Ignoring the US 3.8% NIIT.
Fix: Single filers above $200k MAGI / joint above $250k pay an extra 3.8% on investment income.
UK — forgetting the bed-and-breakfast 30-day rule.
Fix: You can't repurchase the same asset within 30 days to crystallise a loss; HMRC matches the disposal to the repurchase.
🎯 Who This Calculator Is For
Equity investors rebalancing
Plan disposals to stay within favourable brackets.
Property investors
Compute SDLT-adjusted gain on a UK second home or US rental.
Crypto / RSU sellers
Model the tax bite before liquidating large positions.
How Capital Gains Tax Works in the US and UK
A capital gain occurs when you sell a capital asset — stocks, bonds, real estate, cryptocurrency, or collectibles — for more than you paid for it. The profit (gain) is typically subject to capital gains tax. Losses can often be used to offset gains, reducing your tax bill.
In the United States, long-term capital gains (assets held more than 1 year) are taxed at preferential rates of 0%, 15%, or 20% depending on your taxable income. Short-term gains (held 1 year or less) are taxed as ordinary income — at rates from 10% to 37%. High earners may also owe a 3.8% Net Investment Income Tax (NIIT) on investment income above $200,000 (single) / $250,000 (married filing jointly).
In the United Kingdom, Capital Gains Tax (CGT) rates were changed significantly in the October 2024 Autumn Budget. For 2024-25: basic rate taxpayers pay 10% on non-property gains (increased from 10%), 18% on residential property gains (up from 18%). Higher rate taxpayers pay 20% on non-property gains (up from 20%), 24% on residential property gains (unchanged from 24%). The annual CGT exemption was cut to £3,000 in 2024-25.
UK residents benefit from an annual CGT-free allowance (£3,000 in 2024-25, reduced from £12,300 in 2022-23). This means you can realize up to £3,000 in gains each tax year before paying any CGT. Principal Private Residence (PPR) relief means you don't pay CGT on gains from your main home.
🔬 Methodology & Accuracy
Formula: Gain = Sale price − Cost basis − Selling costs. Tax is applied at the appropriate rate band (US long-term 0/15/20%, short-term ordinary income; UK 10/20% non-property, 18/24% property; UK £3,000 annual exemption auto-applied).
Data sources: IRS Publication 550 (2024); HMRC CGT rates updated for the October 2024 Autumn Budget; UK Finance Act 2024.
Last reviewed: January 2026 · Accuracy: Results are precise to two decimal places using IEEE-754 double-precision arithmetic. Intended for educational and planning use only.
For informational purposes only. Results are estimates based on the inputs and formulas provided. For financial, tax, medical, or legal decisions, consult a qualified professional. Rates and regulations change — always verify current figures with official sources.
Accuracy & Feedback
❓ Frequently Asked Questions
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