Fuel Cost Calculator

Fuel cost calculator: trip, commute, and carpool math

This calculator estimates gasoline cost from distance and L/100km or MPG, then multiplies fuel volume by pump price. Commute scaling uses ×5, ×22, and ×260 on the trip total you entered.

What this calculator does

Estimates gasoline cost for a trip or commute from distance, fuel economy, and pump price in metric or imperial units. Optional Round trip doubles distance. Results include fuel volume, an efficiency bucket (Eco-Friendly / Moderate / Fuel-Heavy), CO₂ from fixed emission factors, commute projections (×5 weekly, ×22 monthly, ×260 yearly on the current trip total), and cost per person when passengers share fuel. Calculations run locally in the browser.

Metric fuel volume:

$\text{Liters} = \frac{\text{km}}{100} \times \text{L/100km}$
Imperial fuel volume:

$\text{Gallons} = \frac{\text{miles}}{\text{MPG}}$
Total cost:

$\text{Cost} = \text{fuel volume} \times \text{price per unit}$
CO₂ (this model):

2.31 kg CO₂ per liter (metric display in kg) or 8.89 kg per US gallon (imperial display in lbs). Approximate; blend and driving style shift real tailpipe output.

How the math works

Default metric check: 100 km at 8 L/100km → (100 ÷ 100) × 8 = 8.00 L. At $1.50/L → $12.00 total. Efficiency badge: Moderate (L/100km >6 and ≤10). CO₂: 8 × 2.31 = 18.5 kg. Commute: $12 × 5 = $60/week; × 22 = $264/month; × 260 = $3,120/year. With Round trip, distance doubles first → $24.00 and projections scale from that total. Carpool: total ÷ passenger count; two people on $12 → $6.00 each, 50% savings badge.

Imperial toggle converts inputs (km↔mi, L/100km↔MPG via 235.215, price via 3.78541) so the same physical trip keeps nearly the same total after rounding—defaults become 62.1 mi, 29.4 MPG, $5.68/gal → still about $12.00. Lowering economy on the same distance scales cost linearly: 6 L/100km on 100 km → $9.00 vs $12.00 at 8 L/100km.

Limits of the model

No tolls, parking, maintenance, diesel blends, or EV charging. Commute multipliers assume the same trip on workdays; they do not model vacation weeks or hybrid schedules. Efficiency badges are fixed thresholds, not EPA window-sticker ratings. CO₂ uses combustion averages, not vehicle-specific tests. For route distance before pricing fuel, use the related distance calculator; fold totals into monthly plans with the budget calculator.

Fuel Cost Calculator FAQ

How does this calculator compute trip fuel cost?

Fuel volume comes from distance and economy: metric uses liters = (km ÷ 100) × L/100km; imperial uses gallons = miles ÷ MPG. Total cost = fuel volume × price per liter or gallon. At defaults (100 km, 8 L/100km, $1.50/L), that is 8.00 L and $12.00.

What does the Round trip checkbox do?

It doubles trip distance before fuel math. Same defaults with Round trip on → effective 200 km → 16.00 L → $24.00 total. Commute projection (weekly, monthly, yearly) scales off that higher trip total.

How does the commute projection work?

It multiplies your current trip total (one-way or round-trip, whichever you entered) by 5 for weekly, 22 for monthly, and 260 for yearly. Defaults at $12.00 one-way → $60/week, $264/month, $3,120/year. It assumes that same trip on workdays; it does not add wear, tolls, or parking.

What do the efficiency badges mean?

Metric L/100km: Eco-Friendly ≤6, Moderate >6–10, Fuel-Heavy >10. Imperial MPG: Eco-Friendly ≥40, Moderate 25–39, Fuel-Heavy <25. Default 8 L/100km reads Moderate. They compare your entered economy to fixed buckets, not EPA ratings.

How is CO₂ estimated in the results panel?

Fuel volume × 2.31 kg/L (metric, shown in kg) or × 8.89 kg/US gal (imperial, shown in lbs). At defaults: 8.00 L × 2.31 = 18.5 kg (one decimal). That is a gasoline-combustion average; blend, temperature, and driving style shift real tailpipe output.

How does carpool split work?

Enter People splitting cost (default 1). Cost per person = total fuel cost ÷ passenger count. At 2 people on the $12.00 one-way default → $6.00 per person and 50% savings vs driving alone. Insurance, wear, and depreciation are not included.

What happens when I switch metric and imperial?

The Units toggle converts distance, economy, and price using standard factors (km ↔ miles, L/100km ↔ MPG via 235.215, price per L ↔ per gal via 3.78541). Defaults become 62.1 mi, 29.4 MPG, $5.68/gal; total cost stays $12.00 for the same drive after rounding.

How do I compare better fuel economy on the same trip?

Edit Fuel efficiency and leave distance and price unchanged. On the default 100 km trip at $1.50/L, dropping from 8 to 6 L/100km cuts fuel from 8.00 L to 6.00 L, total cost from $12.00 to $9.00, and the badge from Moderate to Eco-Friendly. Commute projection scales from $3,120/year to $2,340/year.

What does this tool not include?

No tolls, parking, maintenance, diesel vs gasoline blends, or EV charging. Commute scaling is a simple multiply on fuel cost only. CO₂ uses fixed combustion factors, not live grid or vehicle-specific EPA data.

Trip details

How to use this calculator

Reading your fuel cost results

Example: 100 km, 8 L/100km, $1.50/L (metric default)

Fuel efficiency field: 8 → 6 L/100km

Round trip checkbox

Carpool split

Imperial Units toggle