Do I pay before or after pumping gas in the US?

It depends on the station. At the pump you can usually tap or insert a card first, fill up, and the exact amount is charged. Inside, you prepay a dollar amount before the pump turns on. Overnight, many stations only allow prepay.

What does 'prepay' mean at a US gas station?

You go inside first and either hand the cashier a card or pay cash for a set amount tied to your pump number. The pump then unlocks up to that amount. If you paid cash for more than you used, you go back inside for the change.

Which gas grade should I choose?

Regular, the cheapest and lowest octane (87), is right for almost every car including rentals. Only choose mid-grade or premium if the car's fuel door or manual specifically asks for premium.

Is gas sold in litres or gallons in America?

US gallons. One US gallon is about 3.79 litres, so a price like $3.50 works out to roughly $0.92 per litre. Pumps show the total gallons and dollars as you fill.

How to pump gas in the USA, step by step

Filling up in America is quick once you know the rhythm, but a few things differ from home: you often pay before you pump, fuel is sold by the gallon, and the card reader may ask for a US ZIP code. Here's the whole routine.

1. Pull up and pick a side

Drive in so the pump is on the same side as your car's fuel door. Not sure which side? On most cars a small arrow next to the fuel-gauge icon on the dashboard points to it. Switch off the engine.

2. Decide how you'll pay

Two options, and the station decides which are open:

Pay at the pump — tap or insert a card right at the pump. This is fastest, but the reader usually asks for the ZIP code of your card's US billing address. Foreign cards frequently fail this step; if yours does, pay inside instead (see using a foreign card at US gas stations).
Prepay inside — tell the cashier your pump number and pay first, by card or cash, for a set dollar amount. The pump then unlocks. Many stations, especially overnight, only allow this. If you prepaid cash for more than you used, go back inside for the change.

3. Choose your grade

US pumps offer three unleaded grades, and the octane rating is posted on every pump by law (the FTC Fuel Rating Rule):

Regular — 87 octane. The right choice for almost every car, including rentals. Cheapest.
Mid-grade — 88 to 90. Rarely needed.
Premium — 91 to 94. Only if the car specifically calls for it.

Diesel comes from a separate pump, often a different colour handle and a higher price — don't put it in a petrol car. If you're at high altitude in the Rockies, posted octane numbers run a point or two lower, which is normal.

4. Pump the fuel

Lift the nozzle, select your grade if prompted, and squeeze the handle. It clicks off automatically when the tank is full — you don't need to top it up past that. Prices are per US gallon (about 3.79 litres), and the pump counts up gallons and dollars as you go.

5. Take your receipt

At the pump, choose "Yes" for a receipt on screen, or get one from the cashier inside. Keep it — rental companies sometimes ask for proof you refilled, and it's your record of the exact price.

A few American habits worth knowing

Cash can be cheaper. Some stations post two prices, with a small discount for paying cash instead of card.
Pre-authorization holds. Paying at the pump by card can place a temporary hold (often $75–$150) that clears in a few days — worth knowing on a debit card or a card near its limit.
It's self-service — except in New Jersey, and often Oregon, where an attendant may pump for you. See full-service gas: New Jersey, Oregon and pumping your own.

Frequently asked questions

Do I pay before or after pumping gas in the US?: It depends on the station. At the pump you can usually tap or insert a card first, fill up, and the exact amount is charged. Inside, you prepay a dollar amount before the pump turns on. Overnight, many stations only allow prepay.
What does 'prepay' mean at a US gas station?: You go inside first and either hand the cashier a card or pay cash for a set amount tied to your pump number. The pump then unlocks up to that amount. If you paid cash for more than you used, you go back inside for the change.
Which gas grade should I choose?: Regular, the cheapest and lowest octane (87), is right for almost every car including rentals. Only choose mid-grade or premium if the car's fuel door or manual specifically asks for premium.
Is gas sold in litres or gallons in America?: US gallons. One US gallon is about 3.79 litres, so a price like $3.50 works out to roughly $0.92 per litre. Pumps show the total gallons and dollars as you fill.