How to Calculate Crypto Capital Gains

Every time you sell crypto for a profit, the IRS expects a cut, and the size of that cut depends almost entirely on two things: how long you held, and what you paid for it. Get those two numbers right, and capital gains tax is straightforward math. Get them wrong, and you’re either overpaying or setting yourself up for an audit letter.

This guide shows how to calculate crypto capital gains with real examples, which rate applies when, and exactly where the numbers go on your return.

Key Takeaways

• Held under 1 year: ordinary income rates (10–37%). Held over 1 year: 0%, 15%, or 20%.
• Your gain = sale value minus cost basis, and basis depends on which cost method you use.
• The IRS allows specific identification, so you can choose which lots you sell and cut your tax bill legally.
• Crypto-to-crypto trades are taxable at the moment of the swap.
• Everything reports on Form 8949, which rolls into Schedule D.

Short-Term vs Long-Term: The Rate Table

The holding period is measured from the day you acquired the crypto to the day you disposed of it, not the day you bought it with USD, but the day the specific units became yours.

The gap is enormous. A $50,000 gain taxed at 37% short-term costs $18,500. The same gain long-term at 15% costs $7,500, an $11,000 difference from waiting 12 months.

How to Calculate Your Gain

The formula is simple:

Capital Gain = Fair Market Value at Sale − Cost Basis

Cost basis is what you paid, including exchange fees and network fees. The tricky part: if you bought in multiple batches, which batch did you sell? That’s where cost basis methods come in.

The Three Cost Basis Methods

The IRS allows specific identification for crypto if you identify the units at the time of the sale; your exchange’s lot-level records do this automatically on most major platforms.

Worked Example: Three Batches, One Sale

Say you bought Bitcoin in three batches and sold one:

With FIFO, you sell the Jan 2025 lot: gain = $18,000 − $9,000 = $9,000 (long-term, held 19 months: 15% = $1,350).

With specific identification on the Dec 2025 lot instead: gain = $18,000 − $14,000 (0.2 × $70,000) = $4,000 (short-term, 8 months: 24% = $960).

Same sale, two different tax bills. That’s why tracking lots matters, and why crypto tax software is worth the cost for active traders.

Crypto-to-Crypto Swaps

Swapping BTC for ETH is a sale of BTC followed by a purchase of ETH in the IRS’s eyes. The gain or loss on the BTC leg is realized at the moment of the trade, using the fair market value of the ETH you received. Your new basis in the ETH is that same market value.

The IRS’s framework for all of this goes back to Notice 2014-21: crypto is property, and property rules apply to every disposal.

Where the Numbers Go: Form 8949 and Schedule D

Every disposal gets a line on Form 8949, split into four parts: short-term and long-term, each with transactions reported to you (1099-DA) and those that aren’t. The totals flow into Schedule D, which lands on your 1040.

Since the 2025 tax year, crypto brokers report covered transactions on Form 1099-DA; the first full 1099-DA filing season is running in 2026. The form gives you the proceeds, but double-check the cost basis column: brokers report what happened on their platform, and if you moved coins between wallets or bought on another exchange, the basis can be incomplete.

If you hold the crypto in a self-custody wallet, nothing is reported to the IRS automatically, but you still owe the tax. The reporting burden is on you, and the US crypto tax rules guide covers exactly what must be reported.

Common Mistakes

• Using FIFO when specific identification would cut the bill: the IRS lets you choose; most people just don’t.
• Forgetting fees in the basis: a $50 network fee on a $1,000 purchase raises your basis, and that’s legitimate.
• Ignoring crypto-to-crypto swaps: the largest source of underreported gains.
• Not tracking the acquisition date: without it you can’t prove long-term status.
• Assuming your exchange’s 1099-DA is complete: self-custody moves and cross-platform buys break the chain.

FAQ

What’s the difference between short-term and long-term crypto gains? Short-term (held under 1 year) is taxed at ordinary income rates up to 37%. Long-term (over 1 year) is taxed at 0%, 15%, or 20%, a difference worth thousands on large gains.

Can I choose which Bitcoin I sell to minimize tax? Yes, specific identification lets you pick the lots you sell, as long as you identify them at the time of the trade. Most exchanges record this automatically.

Is swapping crypto for crypto a taxable event? Yes. The IRS treats it as selling one asset and buying another; the gain on the sold asset is realized at the swap.

How do I report crypto capital gains? On Form 8949, line by line, with totals flowing into Schedule D on your 1040.

Do I pay tax if I never cashed out to USD? If you swapped or spent crypto, yes, the disposal is taxable in USD terms at the moment of the trade, even if no dollars were involved.

For the complete picture (taxable events, staking income, and loss harvesting), start with the US crypto tax guide. And if you’re sitting on losses this year, our guide to crypto tax loss harvesting shows how to turn them into tax savings.

Sources

• IRS: Frequently Asked Questions on Virtual Currency Transactions

• IRS Publication 544: Sales and Other Dispositions of Assets

• IRS Form 8949 and instructions

Rates and rules change; verify current guidance before filing.