Capital Gains Tax Calculator
This calculator estimates the taxable capital gain and the estimated tax owed when you sell an asset. It supports both aggregated-basis calculations and specific-identification basis when you select particular purchase lots.
Use the fields to input sale proceeds, basis, holding period, and the tax rates that apply to you. For primary residence sales, you may apply a one-time exclusion up to the amount you enter.
Governance
Record a9d1b477d890 • Reviewed by Fidamen Standards Committee
Compute gain using total acquisition cost plus improvements as the basis. Applies primary residence exclusion if selected and distinguishes short-term vs long-term rates by holding period.
Inputs
Advanced inputs
Specific identification inputs
Results
Taxable capital gain
$5,000.00
Estimated tax owed
$750.00
Applicable tax rate
15.00%
Effective tax rate
15.00%
Net proceeds after tax
$9,250.00
| Output | Value | Unit |
|---|---|---|
| Taxable capital gain | $5,000.00 | USD |
| Estimated tax owed | $750.00 | USD |
| Applicable tax rate | 15.00% | — |
| Effective tax rate | 15.00% | — |
| Net proceeds after tax | $9,250.00 | USD |
Visualization
Methodology
The tool computes gross gain as sale proceeds minus adjusted basis. Adjusted basis includes acquisition cost plus capital improvements and may use an identified basis when you select specific-identification.
If you indicate a primary residence and enter an exclusion amount, the calculator subtracts up to that exclusion from the gross gain before applying carried-forward capital losses.
Short-term gains (holding period less than one year) are taxed at your ordinary income rate input; long-term gains use the long-term rate input. The estimated tax owed equals taxable gain multiplied by the selected rate.
Worked examples
Example: You sell 1 unit for $10,000 with an acquisition cost of $5,000 and $0 improvements. Selling expenses are $200 and you held the asset 2 years. Long-term rate 15%. Gross gain = $10,000 − $5,000 = $5,000. Taxable gain = $5,000. Tax owed = $750.
Example (primary residence): If the asset is a primary residence and you qualify for a $250,000 exclusion, and the gross gain is less than $250,000, the taxable gain will be reduced to zero.
F.A.Q.
Can this calculator determine the correct IRS tax bracket for my ordinary income?
No. This tool requires you to enter the ordinary income tax rate and long-term capital gains rate that apply to you. For exact marginal bracket calculations and filing guidance, consult your tax professional or the official tax authority guidance.
Does the calculator handle multiple lots with different acquisition dates and prices?
You can use the specific-identification method to enter the exact identified basis for the lot(s) you sold. For many lots, aggregate the identified basis manually and enter it as a single identified basis.
How accurate are the estimates?
Estimates are mathematical approximations based on your inputs and do not substitute for professional tax advice. They do not account for alternative minimum tax, state taxes, surtaxes, depreciation recapture, or other jurisdiction-specific rules.
What should I do if my situation is complex (e.g., depreciated property, trade or business assets)?
Complex situations may require additional calculations (such as depreciation recapture and section-specific rules). Consult a tax professional or authoritative guidance from your tax authority for those scenarios.
How should I use the primary residence exclusion fields?
Enter 'Yes' if you meet the specific ownership and use tests that permit a primary residence exclusion in your jurisdiction and enter the exclusion amount you expect to claim. The calculator will cap the exclusion at the lesser of the exclusion amount and the gross gain.
Sources & citations
- IRS - Topic No. 409: Capital gains and losses — https://www.irs.gov/taxtopics/tc409
- NIST (standards and best practices) — https://www.nist.gov
- ISO - Standards overview — https://www.iso.org/standards.html
- IEEE - Standards and publications — https://www.ieee.org
- OSHA - Occupational safety and health standards — https://www.osha.gov
- IRS Publication 544 — Sales and Other Dispositions of Assets — https://www.irs.gov/publications/p544
Further resources
Versioning & Change Control
Audit record (versions, QA runs, reviewer sign-off, and evidence).
Record ID: a9d1b477d890What changed (latest)
v1.0.0 • 2025-11-02 • MINOR
Initial publication and governance baseline.
Why: Published with reviewed formulas, unit definitions, and UX controls.
Public QA status
PASS — golden 25 + edge 120
Last run: 2026-01-23 • Run: golden-edge-2026-01-23
Versioning & Change Control
Audit record (versions, QA runs, reviewer sign-off, and evidence).
What changed (latest)
v1.0.0 • 2025-11-02 • MINOR
Initial publication and governance baseline.
Why: Published with reviewed formulas, unit definitions, and UX controls.
Public QA status
PASS — golden 25 + edge 120
Last run: 2026-01-23 • Run: golden-edge-2026-01-23
Engine
v1.0.0
Data
Baseline (no external datasets)
Content
v1.0.0
UI
v1.0.0
Governance
Last updated: Nov 2, 2025
Reviewed by: Fidamen Standards Committee (Review board)
Credentials: Internal QA
Risk level: low
Reviewer profile (entity)
Fidamen Standards Committee
Review board
Internal QA
Entity ID: https://fidamen.com/reviewers/fidamen-standards-committee#person
Semantic versioning
- MAJOR: Calculation outputs can change for the same inputs (formula, rounding policy, assumptions).
- MINOR: New features or fields that do not change existing outputs for the same inputs.
- PATCH: Bug fixes, copy edits, or accessibility changes that do not change intended outputs except for previously incorrect cases.
Review protocol
- Verify formulas and unit definitions against primary standards or datasets.
- Run golden-case regression suite and edge-case suite.
- Record reviewer sign-off with credentials and scope.
- Document assumptions, limitations, and jurisdiction applicability.
Assumptions & limitations
- Uses exact unit definitions from the Fidamen conversion library.
- Internal calculations use double precision; display rounding follows the unit's configured decimal places.
- Not a substitute for calibrated instruments in regulated contexts.
- Jurisdiction-specific rules may require official guidance.
Change log
v1.0.0 • 2025-11-02 • MINOR
Initial publication and governance baseline.
Why: Published with reviewed formulas, unit definitions, and UX controls.
Areas: engine, content, ui • Reviewer: Fidamen Standards Committee • Entry ID: d0da55b164ed