How the calculation works

1. Convert gallons to litres

A U.S. liquid gallon equals 3.785411784 litres. BorderBetter divides the U.S. pump price by this number so it can be compared with a Canadian price per litre.

2. Convert U.S. dollars to Canadian dollars

The U.S. price per litre is multiplied by the USD/CAD exchange rate. The calculator then adds the foreign-exchange percentage you select. The daily Bank of Canada rate is indicative; the rate charged by your card or bank may differ.

3. Estimate the fuel you can buy

Your tank capacity is multiplied by the unfilled portion of your tank. A 60-litre tank that is 25% full can take approximately 45 litres.

4. Compare the fill-up cost

The converted U.S. price, including the selected exchange cost, is compared with the Canadian price. That difference is multiplied by the estimated litres you can buy to produce gross fuel savings.

5. Estimate trip fuel

Round-trip kilometres are multiplied by your fuel economy in litres per 100 kilometres. This estimates the fuel consumed getting there and back. That fuel is valued at the Canadian pump price you entered.

6. Account for trip cost

For a dedicated gas trip, the estimated round-trip fuel cost is deducted from gross fuel savings. If you are already making the trip, that normal travel fuel cost is not deducted because it is not an additional cost of buying gas.

Maximum worthwhile U.S. price

This is the estimated U.S. price per gallon at which calculated net fuel savings reach zero using your current inputs. Below it, U.S. fuel would still save money; above it, the fuel purchase would not.

Limits of the estimate

Real results can change with pump prices, station location, exchange rates, payment-card fees, traffic, driving conditions, idling, vehicle load and actual fuel economy. Border wait time and the value of your time are not currently included.