mycalcstool

Methodology

mycalcstool publishes browser-based calculators. We document the main formulas, tax assumptions, and reference sources that influence the output so users can understand what the estimate includes and what it leaves out.

Finance calculators

Mortgage Calculator uses standard amortization formulas and can add property tax, insurance, PMI, and HOA fees.

Salary Calculator uses 2026 federal tax brackets, standard deductions, FICA rules, and state tax tables stored in the project data files.

Compound Interest Calculator combines the selected compounding frequency with recurring contributions to estimate future value.

Investing calculators

Stock average cost and averaging down calculators use total position cost divided by total shares to estimate a new average cost.

Stock return and foreign stock FX return calculators use purchase value, sale value, entered costs, and exchange rates to estimate scenario returns.

Dividend and ETF recurring investment calculators use user-entered dividend, tax rate, expected return, contribution, and time horizon assumptions.

Investing calculators do not rate securities, recommend trades, or guarantee future returns. Live prices, broker fees, taxes, and exchange rates should be entered or checked by the user.

AI cost calculators

The AI token calculator estimates tokens from text length. Actual token counts vary by model, language, whitespace, punctuation, and tokenizer.

ChatGPT API cost and AI model cost comparison calculators multiply input tokens, output tokens, request count, and editable per-million-token prices.

Default model prices are examples. Before making a budget decision, check the official pricing pages from OpenAI, Anthropic, Google, or the provider you use.

Health and utility calculators

Health calculators use public reference formulas such as BMI or TDEE equations and should be treated as educational estimates only.

Utility calculators use direct mathematical conversions and arithmetic, but input context still matters.

Reference sources

  • IRS, Social Security Administration, and state tax agencies for US payroll and tax rules
  • National Tax Service, National Pension Service, National Health Insurance Service, and Employment Insurance guidance for Korean calculators
  • Publicly available reference equations for BMI, TDEE, due date, and related health estimates

Limits of the result

Calculator outputs are estimates, not legal, medical, tax, or financial advice.

Rates, rules, deduction limits, market prices, exchange rates, and AI model prices can change. Important decisions should be verified with an official source or licensed professional.

Korean finance assumptions were reviewed on April 25, 2026. Investing and AI cost calculator page structure, default explanations, and related links were reviewed on August 6, 2026.

If you spot an outdated rule or formula, send the source and page URL through the Contact page.