Calculation transparency
How our car calculators work.
The formulas, amortisation logic, assumptions and exclusions behind the SouthAfricaCars.com finance, fuel, ownership and settlement tools.
Why this page exists
A calculator is useful only when its assumptions are clear. This page explains how each result is produced, what is included, what is excluded and why a written quote or official figure may differ.
Car finance calculator
Finance repayment and amortisation methodology
The Car Finance Calculator estimates a fixed monthly instalment using vehicle price, deposit, annual interest rate, term and any balloon payment. It can then simulate additional monthly payments and produce monthly and annual repayment schedules.
Amount financed = vehicle price − deposit + financed initiation fee
The initiation fee is added only when the user says it will be financed.
Balloon amount = vehicle price × balloon percentage
The balloon is capped at the amount financed and treated as the intended final balance before optional extra payments.
Monthly rate = annual interest rate ÷ 12
The annual percentage entered by the user is converted to a monthly decimal rate.
Instalment = [r × (P − B ÷ (1 + r)^n)] ÷ [1 − (1 + r)^−n]
P is the amount financed, B is the balloon, r is the monthly rate and n is the number of months.
Monthly debit order = scheduled finance instalment + monthly service fee
The optional extra payment is shown separately because it is not part of the scheduled debit order.
Monthly interest = opening balance × monthly rate
The scheduled principal is the scheduled instalment less that month's estimated interest.
Closing balance = opening balance + interest − scheduled instalment − extra payment
The extra amount is assumed to reduce principal after the scheduled instalment. It cannot reduce the balance below zero.
Total finance paid = scheduled instalments + extra payments + service fees + final balance payment
Total including deposit adds the upfront deposit. Initiation and service fees are also reported separately.
The financed amount less the balloon is divided evenly across the term.
Every extra amount is assumed to reduce principal. A real provider may allocate it differently.
The model stops charging service fees once the simulated balance reaches zero.
If the balance is not cleared early, the amount left after the final scheduled month is shown as the final payment.
Each month shows opening balance, payment, interest, principal, extra payment, fee and closing balance.
Monthly schedule values are grouped into finance years for a more compact overview.
Shareable links store only the entered assumptions in URL parameters. They do not change the formula or create a quote. The page's canonical URL remains the calculator URL without parameters.
Fuel cost calculator
Fuel-cost methodology
The Fuel Cost Calculator converts distance and average consumption into an estimated quantity of fuel, then applies the price entered by the user.
Fuel used = distance travelled ÷ 100 × consumption in litres per 100 km
Fuel cost = fuel used × fuel price per litre
Real consumption can vary with traffic, speed, load, terrain, tyre pressure, weather, driving style and vehicle condition. The calculator does not retrieve a live fuel price automatically.
Total cost of ownership
Ownership-cost methodology
The Total Cost of Ownership Calculator combines finance, fuel and user-entered running costs. It also estimates cash outflow, net cost after resale and cost per kilometre.
Monthly fuel = monthly km ÷ 100 × fuel consumption × fuel price
Monthly running costs = insurance + maintenance + tyres/repairs + parking/tolls + annual licence cost ÷ 12
Monthly all-in cost = monthly finance + monthly fuel + monthly running costs
Estimated net cost = total cash out − estimated resale value
Resale value is an assumption supplied by the user. It is not a valuation and can differ materially from an actual future sale price.
Settlement shortfall calculator
Sale and settlement methodology
The Settlement Shortfall Calculator compares a current written settlement amount with expected private-sale and dealer proceeds.
Net sale proceeds = expected sale price − selling costs
Net position = net sale proceeds − settlement amount
Cash still required = max(0, settlement amount − net sale proceeds − cash available)
The result is only as current as the settlement quote and sale estimates entered. It does not predict the lender's final settlement on a later date.
Rounding and display
Calculations use unrounded JavaScript numbers internally. Currency results are generally displayed to the nearest rand, so totals reconstructed from displayed values may differ slightly from the calculator's internal totals.
What the calculators do not do
- They do not retrieve or recommend a live interest rate, fuel price, fee or resale value.
- They do not perform a credit assessment or determine affordability.
- They do not reproduce every contractual feature used by every finance provider.
- They do not account automatically for missed payments, late fees, daily-interest conventions or insurance products.
- They do not replace a written finance quote, settlement quote, valuation or professional advice.
Calculator logic is reviewed when features or formulas change. The finance methodology was last updated on 21 July 2026 to document amortisation schedules, extra-payment assumptions and shareable calculation links.
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Last reviewed: 21 July 2026. This methodology is provided for transparency and general information. Calculator results remain estimates and are not financial, legal, tax, insurance or mechanical advice.