Stock Profit Calculator
This calculator estimates profit, return on investment (ROI) and annualized return for a single stock trade. It supports commissions, dividends, a simple stock-split factor and a user-provided tax-rate assumption.
Use the basic mode for a quick result and the detailed mode for an estimated post-tax result. Results are for informational purposes and not tax, legal or investment advice.
Governance
Record aca644ada6e3 • Reviewed by Fidamen Standards Committee
Adds a simple, user-configurable tax estimate on realized gains and reports net profit and net ROI. Use this as an estimate only; tax laws vary and actual calculations may require tax lot-level data.
Inputs
Results
Net profit after estimated tax (USD)
$161.50
Estimated tax on gain (USD)
$28.50
Net return on investment
16.07%
Annualized return after tax (CAGR)
16.07%
| Output | Value | Unit |
|---|---|---|
| Net profit after estimated tax (USD) | $161.50 | USD |
| Estimated tax on gain (USD) | $28.50 | USD |
| Net return on investment | 16.07% | % |
| Annualized return after tax (CAGR) | 16.07% | % |
Visualization
Methodology
Calculations follow standard financial math for trade cash flows: total cost = buy price × shares + buy fees; total proceeds = sell price × shares − sell fees; dividends are added to proceeds before computing profit and returns.
Annualized return is computed using a compound annual growth rate (CAGR) approximation: (ending value / beginning value)^(1 / years) − 1. Tax estimates are a simple percentage applied to an estimated taxable gain and do not replace tax-professional calculations.
Worked examples
Example: Buy 100 shares at $10, sell at $12 after 365 days, $5 commissions each side, no dividends. Gross profit ≈ $100, ROI ≈ 10%, annualized ≈ 10%.
Example with tax: Same trade with a 15% tax rate on estimated gains → estimated tax ≈ $15, net profit ≈ $85.
F.A.Q.
How accurate are results?
Results use standard arithmetic and are validated against unit tests. Accuracy for floating-point arithmetic follows typical double-precision behavior. This tool provides estimates; rounding, broker-specific fee structures, tax rules and lot accounting can change real outcomes.
Does the calculator handle multiple buy/sell lots or partial sales?
No. This calculator models a single aggregated trade (one buy block, one sell block). For multiple lots or partial sales, you should run multiple calculations or use accounting that supports per-lot basis.
Is the tax estimate exact?
No. Tax is a simple percentage applied to an estimated taxable gain. It does not model short-term vs long-term rates, exemptions, deductions or jurisdictional specifics. Consult a tax professional for precise tax treatment.
Why is the annualized return sometimes undefined or extreme?
Annualized return uses the ratio of ending to starting value and exponentiation by 1/years. Very small or negative starting values, zero holding period, or negative net proceeds can produce undefined, very large, or complex values. The tool requires a positive total cost and a holding period greater than zero for a meaningful CAGR.
Sources & citations
- National Institute of Standards and Technology (NIST) — https://www.nist.gov
- International Organization for Standardization (ISO) — https://www.iso.org
- Institute of Electrical and Electronics Engineers (IEEE) — https://www.ieee.org
- U.S. Securities and Exchange Commission (SEC) — Investor guidance — https://www.sec.gov
- Internal Revenue Service (IRS) — Tax guidance — https://www.irs.gov
- SEC — Investor.gov Educational Resources — https://www.investor.gov/
- CFA Institute — Global Investment Performance Standards (GIPS) — https://rpc.cfainstitute.org/gips-standards
- FINRA — Investment Products — https://www.finra.org/investors/investing/investment-products
Further resources
Versioning & Change Control
Audit record (versions, QA runs, reviewer sign-off, and evidence).
Record ID: aca644ada6e3What changed (latest)
v1.0.0 • 2025-11-06 • 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 • 2025-11-06 • 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 6, 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 • 2025-11-06 • 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: 384edbaebc23