Fuel Cost Calculator

Yes. This Fuel Cost Calculator estimates the raw petrol/diesel cost of a trip, commute, or year of driving — it's a household budgeting tool. The IRD kilometre rate (see our Kilometre Rate Calculator) is a tax reimbursement figure for sole traders, partners, and trust beneficiaries claiming vehicle expenses — it bundles in depreciation, insurance, registration, and RUC via a fixed $/km rate set by IRD, not just fuel. Use this calculator to budget your fuel spend; use the kilometre rate calculator to work out an IRD-compliant business vehicle claim.

Litres used = total distance (km) × fuel efficiency (L/100km) ÷ 100. Cost = litres used × fuel price ($/L). For a daily commute, the per-trip figure is multiplied by your chosen days per week, then by 52 weeks to get an annual figure.

No — this is a fuel-only estimate. Diesel and electric vehicles in NZ pay Road User Charges separately, billed per km travelled rather than per litre of fuel, so RUC isn't part of a $/L fuel calculation. The default diesel price (2.10/L) reflects pump price only — budget RUC on top if you drive a diesel or EV.

The default petrol price ($2.85/L) is an indicative national average sourced from MBIE's weekly fuel price monitoring. Actual pump prices vary by region, retailer, and day — often by 20–30 cents per litre. Always check the price you're actually paying and edit the field before relying on the result.

It depends on the vehicle and driving conditions (city stop-start driving uses noticeably more fuel than open-road driving). As a starting point: small cars sit around 6.5 L/100km, medium cars around 8.0, SUVs around 10.0, utes/4WDs around 11.5, and hybrids around 4.5. Your vehicle's actual combined-cycle figure is usually printed on the fuel economy label or in the owner's manual — use that instead of the preset if you know it.