An explanation of the formulas, data sources, and update process behind every calculator on this site.
Every calculator on MegaCalcOnline.com is built around official Australian formulas, rates, and thresholds — not generic international assumptions. This page explains where our data comes from, how often it's updated, and how to interpret the results you see.
Income tax, Medicare levy, HECS-HELP, and salary calculators use the current financial year's ATO individual income tax rates and thresholds, including the Medicare levy and low income tax offset (LITO) where applicable. Superannuation calculators use current ATO contribution caps and ASFA benchmark figures.
Mortgage repayment calculations use standard amortisation formulas (principal and interest split across the loan term). Stamp duty calculators use each state and territory's published duty rates and first home buyer concession thresholds. Interest rate defaults are illustrative — always check your lender's current rate, which will differ from any example shown.
BMI, BMR, and body composition calculators use internationally recognised formulas (such as the Mifflin-St Jeor equation for BMR) that are standard in clinical and fitness contexts. These tools provide general estimates only and are not a substitute for professional medical or health advice.
Math, date/time, and unit conversion calculators use standard mathematical formulas and internationally recognised conversion factors, verified against standard reference sources.
Australian tax brackets, superannuation caps, and government payment rates typically change at the start of each financial year (1 July) or when legislation passes. We review and update calculators against new ATO, Services Australia, and ASFA figures as they're published. Each calculator page displays a "Last Updated" date so you can see when it was last reviewed.
| Topic | Primary Source |
|---|---|
| Income tax, GST, Division 293 | Australian Taxation Office (ato.gov.au) |
| Superannuation caps & benchmarks | ASFA, ATO Super guidance |
| Age Pension, Centrelink payments | Services Australia |
| Interest rates, cash rate context | Reserve Bank of Australia (RBA) |
| Stamp duty by state | Each state/territory Revenue Office |
| General financial literacy guidance | Moneysmart (ASIC) |
| Health formulas (BMI, BMR, etc.) | Standard clinical/fitness reference formulas |
Every calculator on this site provides an estimate for general informational purposes only. Results do not account for every individual circumstance — such as specific deductions, offsets, exemptions, or personal financial history — and should not be relied upon as financial, tax, legal, or medical advice. Always confirm important calculations with a registered tax agent, licensed financial adviser, mortgage broker, or medical professional before making a decision.
Found a calculation that looks incorrect, or a rate that's out of date? Please let us know via our Contact page — we review and correct genuine errors promptly.