Check the vehicle owner's manual: The owner's manual typically lists the bulb types used in the vehicle. Check the section on headlights for the bulb type information.
Check the old bulb: If you have removed the old bulb, you can look for markings and numbers on the bulb itself. Typically, there will be a number or model on the bottom or near the bottom of the bulb.
Search online: You can use the internet to search for bulb types. Many automotive parts websites offer bulb type lookup tools where you can input your vehicle make, model, and year to find the correct bulb type.
Consult an automotive repair shop: If you're still unable to determine the correct bulb type, you can consult with a local automotive repair shop. They can provide you with the correct bulb type based on your vehicle information and assist with the replacement of the bulb.