Choose a consistent period
Build the budget annually, then divide by twelve if a monthly figure is useful. Separate recurring costs from one-off purchase and preparation costs. Include the items that apply to your situation, and do not assume another owner’s insurance or licensing cost will be yours.
Use your own figures
Get actual quotes and use receipts when available. Keep estimates labelled as estimates. Fuel use varies with journeys, conditions and the vehicle; a brochure figure may not match your use. Record what you included so comparisons can be repeated fairly.
Allow for uncertainty
A maintenance reserve is planned money, not proof that a particular repair will happen. Choose a reserve that fits the car’s condition and your ability to handle a bill. Review it after inspection or servicing rather than treating it as a guaranteed annual total.
Compare the trade-offs
A car with lower fuel use may have higher purchase, insurance or repair costs. A useful comparison shows the assumptions alongside the totals. The site calculator estimates costs from your entries; it does not quote a finance product or predict resale value.