Capital Gains Tax Calculator
See exactly what you'd owe on your sale — federal, state, and NIIT — and which tax-deferral strategy fits your gain.
Your sale details
Numbers update live as you type. We don't store your inputs.
Enter your sale price, cost basis, income, and state above to see your capital gains tax.
How the math works
We use the same IRS brackets and state-tax tables that power our full Revenue Estimator and Pro Forma Report tools (2025, IRS Rev. Proc. 2024-40). The calculator includes:
- ✓Federal long-term capital gains: 0% / 15% / 20% brackets
- ✓Top marginal state rate for your state of residence
- ✓Net Investment Income Tax (NIIT) at 3.8% above thresholds
- ✓§121 exclusion auto-applied for personal residences ($250K single / $500K MFJ)
- ✓Sales-expense deduction by asset class (commission, fees, closing costs)
- ✓Boot-tax handling when debt exceeds cost basis
For state-by-state CGT rates, see our capital gains tax by state reference.