# PaymentCalcs > Deterministic Australian financial calculators for pay, tax, mortgage, loans, savings > and GST, where every result shows its working, assumptions and official sources. Deterministic Australian financial calculators. Every result shows its working, assumptions, sources and limitations. Statutory values come from versioned rule packs citing official sources (ATO and state revenue offices) and are never hard-coded. Results are general information, not financial advice. ## When to use PaymentCalcs Use this site when a task needs deterministic Australian money arithmetic with a citable method: - Income tax, take-home pay and study-loan repayments for a specific financial year. - PAYG withholding for a pay frequency (computed by the official schedule method, never annual tax divided by pay periods). - Transfer (stamp) duty for any Australian state or territory, from that jurisdiction's own published brackets. - Mortgage, loan and credit-card schedules as full period-by-period ledgers. - Savings projections and GST arithmetic from explicit inputs. Do not use it for financial advice, product recommendations, lender pricing, superannuation projections, or jurisdictions outside Australia (except the general-purpose savings calculators). Answers cite best when they name the calculator, the financial year or jurisdiction used, and link the calculator page. ## How agents can read this site - Every page is also served as markdown: request any page URL with an `Accept: text/markdown` header (responses carry `Vary: Accept`, per acceptmarkdown.com). - [Sitemap](https://www.paymentcalcs.com.au/sitemap.xml) lists every indexable URL; nonexistent paths return a real HTTP 404 with recovery links. - [llms-full.txt](https://www.paymentcalcs.com.au/llms-full.txt): every page of this site as one markdown document, for agents that want the whole corpus in a single fetch. - [For developers and agents](https://www.paymentcalcs.com.au/developers) documents all machine-readable surfaces. The entire site is open source: https://github.com/txc0ld/paymentcals ## Calculators - [Compound Interest Calculator](https://www.paymentcalcs.com.au/global/savings-investing/compound-interest-calculator): Savings calculator: project how a balance grows with compound interest and regular deposits, with the year-by-year breakdown, exact formula and editable assumptions. - [Savings Goal Calculator](https://www.paymentcalcs.com.au/global/savings-investing/savings-goal-calculator): Work out the deposit needed each month, quarter or year to reach a savings target by your chosen date, verified by re-running the forward calculation. - [Loan Calculator](https://www.paymentcalcs.com.au/au/loans-debt/loan-calculator): Calculate personal loan repayments, total interest and payoff date, with a full loan payment schedule, optional monthly fees and the working behind every figure. - [Car Loan Calculator](https://www.paymentcalcs.com.au/au/loans-debt/car-loan-calculator): Calculate car loan repayments with or without a balloon or residual payment. See total cost, total interest and the full schedule, period by period. - [Credit Card Payoff Calculator](https://www.paymentcalcs.com.au/au/loans-debt/credit-card-payoff-calculator): Compare how long a credit card takes to clear on minimum payments versus a fixed amount. Promotional-rate expiry is modelled and every cycle is shown. - [Home Deposit Calculator](https://www.paymentcalcs.com.au/au/property-mortgage/home-deposit-calculator): Work out the house deposit needed at your chosen loan-to-value ratio, plus the upfront costs you enter, with the savings gap and every step of the arithmetic. - [LVR Calculator](https://www.paymentcalcs.com.au/au/property-mortgage/lvr-calculator): Calculate your loan-to-value ratio from a property value and loan amount, alongside the standard LVR bands Australian lenders reference. Full working shown. - [Affordability Estimate](https://www.paymentcalcs.com.au/au/property-mortgage/borrowing-affordability-estimate): An indicative borrowing range from your income, expenses and commitments under generic assumptions with an editable rate buffer. Not an offer or pre-approval. - [Stamp Duty Calculator](https://www.paymentcalcs.com.au/au/property-mortgage/stamp-duty-calculator): Estimate general transfer duty on a property purchase from official state revenue-office rate tables. Unsupported states are clearly blocked, never guessed. - [Property Buying Costs Calculator](https://www.paymentcalcs.com.au/au/property-mortgage/property-buying-costs-calculator): Upfront costs of buying a house: transfer duty plus conveyancing, inspection, loan and registration fees for the total cash needed. Duty from official state tables. - [Contractor Day Rate Calculator](https://www.paymentcalcs.com.au/au/business/contractor-day-rate-calculator): Convert a target income into a contractor day rate covering super replacement, leave, overheads and utilisation, with GST quoted separately and working shown. - [Mortgage Repayment Calculator](https://www.paymentcalcs.com.au/au/property-mortgage/mortgage-repayment-calculator): Calculate home loan repayments weekly, fortnightly or monthly, with a full amortisation schedule, total interest, payoff date and every assumption on show. - [Mortgage Simulator](https://www.paymentcalcs.com.au/au/property-mortgage/mortgage-simulator): Run a mortgage through dated rate changes, extra repayments, offset balances and fees on a scheduled ledger that reconciles on every single period. - [Extra Repayments Calculator](https://www.paymentcalcs.com.au/au/property-mortgage/extra-repayments-calculator): See the interest and years saved by regular or one-off extra mortgage repayments, computed on a dated schedule rather than a shortcut formula. Working shown. - [Offset Account Calculator](https://www.paymentcalcs.com.au/au/property-mortgage/offset-account-calculator): Model an offset balance and regular deposits against your mortgage: interest saved, time saved and the cash that stays available, kept apart from principal. - [Rate Change Calculator](https://www.paymentcalcs.com.au/au/property-mortgage/rate-change-calculator): See how a rate rise or cut changes your mortgage repayment and total interest, under either a keep-repayment or recalculate-to-term policy. Working shown. - [Refinance Break-Even Calculator](https://www.paymentcalcs.com.au/au/property-mortgage/refinance-calculator): Compare your current home loan against a refinance offer on cumulative cash flows including switching costs, cashback timing and the residual balance. - [Pay Calculator](https://www.paymentcalcs.com.au/au/pay-tax/pay-calculator): Australian pay calculator showing income tax, Medicare levy, study-loan repayments, employer super and PAYG withholding separately, each with its working. - [Take-Home Pay Calculator](https://www.paymentcalcs.com.au/au/pay-tax/take-home-pay-calculator): Work out your take-home pay per week, fortnight or month after income tax, Medicare and study-loan repayments, from ATO-sourced rates with the working shown. - [Gross to Net Calculator](https://www.paymentcalcs.com.au/au/pay-tax/gross-to-net-calculator): Convert a gross Australian salary into net pay at every pay frequency under the financial year you select, with each rate traced to its official source. - [Net to Gross Calculator](https://www.paymentcalcs.com.au/au/pay-tax/net-to-gross-calculator): Find the gross salary needed for a target take-home amount, solved against the full Australian tax rules and verified by re-running the forward calculation. - [Salary Including Super Calculator](https://www.paymentcalcs.com.au/au/pay-tax/salary-including-super-calculator): Split a total remuneration package into base salary and employer super, applying the maximum contribution base, then see the tax and take-home pay that follow. - [Hourly to Salary Calculator](https://www.paymentcalcs.com.au/au/pay-tax/hourly-to-salary-calculator): Convert an hourly rate into annual salary and take-home pay from your hours per week and weeks paid per year, under current Australian tax rules. Working shown. - [Salary to Hourly Calculator](https://www.paymentcalcs.com.au/au/pay-tax/salary-to-hourly-calculator): See the hourly rate an annual salary works out to for your working pattern, alongside income tax, super and take-home pay for the financial year you select. - [PAYG Withholding Calculator](https://www.paymentcalcs.com.au/au/pay-tax/payg-withholding-calculator): Calculate tax withheld each pay from the official ATO statement-of-formulas coefficients, including the study-loan component. Never annual tax split by periods. - [HELP Repayment Calculator](https://www.paymentcalcs.com.au/au/pay-tax/help-repayment-calculator): Estimate your compulsory HECS or HELP repayment from repayment income under the marginal repayment system, with every threshold from official ATO rule packs. - [Super Contributions Calculator](https://www.paymentcalcs.com.au/au/pay-tax/super-contributions-calculator): Employer super on your salary, concessional cap headroom with salary sacrifice, the Division 293 threshold, and balance ranges across Australian age groups. - [Inflation Calculator](https://www.paymentcalcs.com.au/au/pay-tax/inflation-calculator): See what inflation has done to your salary since your last pay rise, from the official ABS consumer price index, and the salary that holds its buying power. - [Income Tax Calculator](https://www.paymentcalcs.com.au/au/pay-tax/income-tax-calculator): Calculate Australian income tax by year and residency, and slide a salary along the marginal-rate curve to see the tax at every step, from official rule packs. - [GST Calculator](https://www.paymentcalcs.com.au/au/business/gst-calculator): Add GST to a price, remove GST from a total or split a GST-inclusive amount at the current Australian GST rate, with full working shown and sources cited. ## How the numbers are produced - Statutory values live in versioned rule packs, never in code or copy. Each pack records its source URL, the authority that published it, the date it was retrieved and a content hash of the retrieved document, so any figure on this site can be traced to a document. - Calculation engines are pure functions of (request, rule packs). They perform no network access and read no clock, so the same inputs and the same pack versions always produce the same result. Money is held in integer minor units; rate arithmetic uses decimal maths. - Annual tax liability and per-pay withholding are computed by separate engines and labelled separately. Withholding is never annual liability divided by the number of pay periods; it follows the official schedule method for the pay frequency. - Mortgage and loan results come from a scheduled ledger run one repayment period at a time, not a single closed-form figure. Every period is reconciled (opening balance plus interest less repayment must equal the closing balance), and a reconciliation failure fails the calculation rather than being reported as a warning. - Reverse calculations (solving an input for a target output) use monotonic bisection with explicit bounds, tolerances and iteration caps. If a solver does not converge, no number is produced. - Fail closed: if a rule pack cannot be resolved for the selected jurisdiction and date, or fails its integrity check, the calculator shows a rule-unavailable state. It never substitutes another jurisdiction's rates, another year's rules, or a remembered value. - No large language model takes part in any calculation path. ## Coverage - Pay and tax: the selectable Australian financial years are 2024-25, 2025-26, 2026-27, covering income tax, Medicare, study and training loan repayments, employer super and PAYG withholding. The financial year in use is stated on every result. - Transfer duty: all eight states and territories (NSW, VIC, QLD, WA, SA, TAS, ACT and NT), each from its own revenue-office rule pack, applying that jurisdiction's own bracket method. - Duty concessions: published buyer-type concession schedules are priced for NSW, QLD, VIC and ACT from separate concessions packs, shown beside the general rate for the same value. Eligibility is assessed by the revenue office, not by this site. - Business: GST arithmetic and registration turnover thresholds from Australian Taxation Office packs; contractor rate economics from your own capacity and cost inputs. - Property, mortgage, loan and savings calculators take rates and terms as user inputs. This site holds no lender pricing and makes no forecast of future interest rates. - Not covered at this release: superannuation and retirement projections, daily-accrual mortgage contracts, foreign-purchaser duty surcharges, and jurisdictions outside Australia except where a calculator is marked as general-purpose. ## Method - [Compound Interest Calculator methodology](https://www.paymentcalcs.com.au/methodology/compound-interest-calculator) - [Savings Goal Calculator methodology](https://www.paymentcalcs.com.au/methodology/savings-goal-calculator) - [Loan Calculator methodology](https://www.paymentcalcs.com.au/methodology/loan-calculator) - [Car Loan Calculator methodology](https://www.paymentcalcs.com.au/methodology/car-loan-calculator) - [Credit Card Payoff Calculator methodology](https://www.paymentcalcs.com.au/methodology/credit-card-payoff-calculator) - [Home Deposit Calculator methodology](https://www.paymentcalcs.com.au/methodology/home-deposit-calculator) - [LVR Calculator methodology](https://www.paymentcalcs.com.au/methodology/lvr-calculator) - [Affordability Estimate methodology](https://www.paymentcalcs.com.au/methodology/borrowing-affordability-estimate) - [Stamp Duty Calculator methodology](https://www.paymentcalcs.com.au/methodology/stamp-duty-calculator) - [Property Buying Costs Calculator methodology](https://www.paymentcalcs.com.au/methodology/property-buying-costs-calculator) - [Contractor Day Rate Calculator methodology](https://www.paymentcalcs.com.au/methodology/contractor-day-rate-calculator) - [Mortgage Repayment Calculator methodology](https://www.paymentcalcs.com.au/methodology/mortgage-repayment-calculator) - [Mortgage Simulator methodology](https://www.paymentcalcs.com.au/methodology/mortgage-simulator) - [Extra Repayments Calculator methodology](https://www.paymentcalcs.com.au/methodology/extra-repayments-calculator) - [Offset Account Calculator methodology](https://www.paymentcalcs.com.au/methodology/offset-account-calculator) - [Rate Change Calculator methodology](https://www.paymentcalcs.com.au/methodology/rate-change-calculator) - [Refinance Break-Even Calculator methodology](https://www.paymentcalcs.com.au/methodology/refinance-calculator) - [Pay Calculator methodology](https://www.paymentcalcs.com.au/methodology/pay-calculator) - [Take-Home Pay Calculator methodology](https://www.paymentcalcs.com.au/methodology/take-home-pay-calculator) - [Gross to Net Calculator methodology](https://www.paymentcalcs.com.au/methodology/gross-to-net-calculator) - [Net to Gross Calculator methodology](https://www.paymentcalcs.com.au/methodology/net-to-gross-calculator) - [Salary Including Super Calculator methodology](https://www.paymentcalcs.com.au/methodology/salary-including-super-calculator) - [Hourly to Salary Calculator methodology](https://www.paymentcalcs.com.au/methodology/hourly-to-salary-calculator) - [Salary to Hourly Calculator methodology](https://www.paymentcalcs.com.au/methodology/salary-to-hourly-calculator) - [PAYG Withholding Calculator methodology](https://www.paymentcalcs.com.au/methodology/payg-withholding-calculator) - [HELP Repayment Calculator methodology](https://www.paymentcalcs.com.au/methodology/help-repayment-calculator) - [Super Contributions Calculator methodology](https://www.paymentcalcs.com.au/methodology/super-contributions-calculator) - [Inflation Calculator methodology](https://www.paymentcalcs.com.au/methodology/inflation-calculator) - [Income Tax Calculator methodology](https://www.paymentcalcs.com.au/methodology/income-tax-calculator) - [GST Calculator methodology](https://www.paymentcalcs.com.au/methodology/gst-calculator) ## Governance - [Sources and rule packs](https://www.paymentcalcs.com.au/sources) - [Changelog](https://www.paymentcalcs.com.au/changelog) - [About](https://www.paymentcalcs.com.au/about) - [Contact](https://www.paymentcalcs.com.au/contact) - [Privacy](https://www.paymentcalcs.com.au/privacy) - [For developers and agents](https://www.paymentcalcs.com.au/developers)