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calcthai.com · Car Ownership Cost Calculator
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Car Ownership Cost Calculator
Add up depreciation, finance interest, fuel, insurance, road tax and compulsory insurance, maintenance and parking to see the real cost of owning a car per month and per kilometre.
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Add up depreciation, finance interest, fuel, insurance, road tax and compulsory insurance, maintenance and parking to see the real cost of owning a car per month and per kilometre.
How it works
Depreciation = price × (1 − resale share). Fuel a year = yearly distance ÷ economy × fuel price. Yearly cost = fuel + insurance + tax and compulsory insurance + maintenance + monthly parking × 12. Total = depreciation + finance interest + yearly cost × years, then divided by total months and total kilometres.
Hand check: an THB 800,000 car resold at 50% loses THB 400,000. 10,000 km a year at 10 km per litre and THB 30 fuel costs THB 30,000 a year. Over 5 years with no other costs the total is THB 550,000: THB 9,166.67 a month or THB 11 per km.
Uses constant yearly averages; real fuel prices, premiums and repairs change with time and vehicle age. Resale value depends on the market and condition. For a financed car, enter total contract interest, not all instalments, because principal is already in the price.
Frequently asked questions
Why not enter all instalments?
Instalments contain principal and interest. Principal is the car price, already counted through depreciation, so adding all instalments would double-count it.
What should I enter for road tax and compulsory insurance?
Use last year's receipts, or calculate road tax with the road tax tool and add the compulsory insurance premium.
What is cost per kilometre useful for?
Compare it with taxis, public transport or mileage claims, and when deciding whether a second car is worthwhile.
Sources
Method last verified 21 Sep 2026