Capital Gains Tax Calculator

A capital gains tax calculator estimates the federal tax you owe on the profit from selling a capital asset — a stock, ETF, bond, real estate property, cryptocurrency, or collectible — for more than you paid for it. The IRS taxes these profits differently depending on how long you held the asset before selling, your total taxable income, and your filing status.

The most important dividing line is the one-year holding period. Assets sold within 365 days of purchase produce short-term capital gains, taxed at your ordinary income rate (10%–37% in 2024). Assets held for more than one year produce long-term capital gains, taxed at the preferential rates of 0%, 15%, or 20% — a significant difference that can mean tens of thousands of dollars in tax savings on the same gain.

This calculator applies the 2024 U.S. federal tax brackets for both short-term and long-term gains, accounts for the 3.8% Net Investment Income Tax (NIIT) on high earners, applies the $3,000 capital loss deduction limit with carryover tracking, and handles multiple assets simultaneously — making it suitable for modeling an entire year's worth of investment transactions.

Disclaimer: This calculator provides estimates for educational purposes only. Tax law is complex and changes frequently. Consult a qualified tax professional for advice specific to your situation.

The calculator applies a multi-step process that mirrors how the IRS actually computes capital gains tax:

Worked example: You are single with $80,000 ordinary income. You sell a stock held 18 months for a $20,000 long-term gain. Your total income = $100,000 — within the 15% long-term bracket (up to $518,900 for single filers in 2024). Long-term tax = $20,000 × 15% = $3,000. No NIIT (income under $200,000). Effective rate on the gain = 15%. If you had held less than one year, the same $20,000 would be taxed at your 22% marginal rate = $4,400 — a $1,400 difference from simply waiting a few more months.

The short-term vs. long-term distinction is the most important concept in capital gains taxation. Short-term gains are simply added to your ordinary income and taxed at the same rate as your wages. Long-term gains are stacked on top of ordinary income but taxed using a separate, lower rate schedule. The threshold is exactly one year — the day you sell must be at least 366 days after the day you bought for the holding period to qualify as long-term.

The Net Investment Income Tax (NIIT) is an additional 3.8% Medicare surtax introduced by the Affordable Care Act that applies to net investment income (which includes capital gains) for taxpayers above certain income thresholds: $200,000 for single filers, $250,000 for married filing jointly. The NIIT applies to the lesser of your net investment income or the amount by which your modified adjusted gross income exceeds the threshold — meaning it applies to only the portion of gains that push you above the limit, not all gains.

Special rules for specific asset types: Not all assets follow the standard 0/15/20% schedule. Collectibles (art, coins, wine, antiques) are capped at a maximum 28% long-term rate, regardless of income — still preferential vs. 37% ordinary income, but not as low as stocks. Unrecaptured Section 1250 gain on the sale of depreciable real estate (the portion attributable to prior depreciation deductions) is capped at 25%. Cryptocurrency is treated as property — all the same short-term/long-term rules apply, and each trade (including crypto-to-crypto swaps) is a taxable event.

Capital loss rules: Capital losses must be applied in a specific order. Short-term losses first offset short-term gains, and long-term losses first offset long-term gains. Any excess losses then cross over to offset gains of the opposite type. If total losses still exceed total gains, up to $3,000 of net loss can offset ordinary income per year. Losses beyond $3,000 carry forward indefinitely to future tax years — this carryover is tracked in the calculator's results panel.