How this calculator works
Fuel cost is only one slice of what a kilometer actually costs — insurance, tax, and maintenance are fixed yearly costs that keep accruing whether you drive a lot or a little. Spreading each of those over your annual distance turns them into a per-kilometer figure you can add to fuel cost.
More detail
Why fuel-only estimates undercount real cost
Insurance, tax, and routine maintenance don't scale down just because you drove fewer kilometers this year — they're largely fixed. That means the less you drive, the higher your true per-km cost climbs, even though fuel cost per km stays the same, because the same fixed costs are spread over fewer kilometers.
Low mileage isn't automatically cheap. A car driven only 5,000 km a year still pays full insurance and tax, so its true cost per km can be several times higher than a car driven 20,000 km a year with the same fixed costs. If cost-per-km is what matters to you, driving more (within reason) can actually lower it.
Frequently asked questions
For 15,000 km a year, 12 km/L, and 1,700 won/L fuel, what's the fuel cost per km?
Fuel cost per km = 1,700 ÷ 12 ≈ 141.7 won/km.
With insurance 800,000, tax 300,000, and maintenance 500,000 won a year added in, what's the total cost per km?
Those three add up to about 106.7 won/km (53.3 + 20.0 + 33.3 before rounding), so combined with the 141.7 won/km fuel cost the total is roughly 248.3 won/km.
Why does driving less increase my per-km cost?
Insurance, tax, and much of maintenance are fixed annual amounts. Spread over fewer kilometers, each kilometer carries a bigger share of those fixed costs — so low-mileage driving raises cost per km even though total spending is lower.