A spark plug is very essential for every vehicle. The basic function of a spark plug is to ignite the engine. Over the century, modern vehicles have changed in several ways and the same is the case for spark plugs. We can distinguish them based on their sizes by determining the dimension of the thread or nut. They are available in different metals that can boost the engine’s performance. Every car owner has the most common question, ‘Are all spark plugs the same size?’ Many vehicle owners will always search the exact size of spark plugs that can fit their vehicles. You can easily get your spark plug from a nearby automobile shop or order them online. It is necessary that you get the right size of spark plug for your vehicle, or it may cause major damage to your vehicle.
Are all Spark Plugs the Same size?
The following table will help you to choose the correct size of spark plugs for your vehicle. These plugs are available in various sizes and are to be used according to the requirement of your vehicle.
What sizes are spark plugs available in?
Spark plug sizes in inches
Spark plug size in mm
|Motorcycle, scooter, small cars
|Lawnmowers/ small engines
|Ford, Newer Asian cars
|18mm bi hex
Depending on the size, each spark plug can be used with a specific type of cylinder in a vehicle. There are multiple cylinders in a vehicle, implying multiple spark plugs in your automobile. It is not necessary that all of them are of the same size.
Generally, spark plugs are differentiated based on the metal used. The various types of spark plugs based on the metal used are Copper, Platinum, and Iridium. All these plugs can be found in various sizes and have their specific usage. However, many car owners prefer platinum spark plugs due to their durability and excellent performance.
You should pick the best spark plug according to your requirement and keep in mind the car’s performance. It is advisable that you do not upgrade your copper spark plugs to platinum ones as there are more chances of damage to your engine and its performances.
Copper Spark Plugs:
Copper spark plugs contain solid copper and are good in electrical conductivity. These plugs are the most commonly available ones at a very cheap price. As it has the largest diameter, it needs more voltage to generate a spark. These plugs have a shorter life span but provide more power and good performance. Copper spark plugs are available in various sizes and can be used for vehicles depending on the size of the cylinder. These plugs are economical but used less nowadays as they are not reliable and need to be changed more frequently. These were most commonly used in older vehicles built up before the 1980s.
Platinum Spark Plugs:
Platinum is a much harder metal used in spark plugs. One of the advantages of this spark plug is its durability. Platinum comes in two categories- single and double platinum. A single platinum spark plug is similar to a copper spark plug with a platinum disc welded to the tip of the center electrode, whereas a double platinum spark plug has both the side electrodes welded with platinum. For higher performance, you should select a double platinum spark plug. Platinum spark plugs are available in various sizes and the most commonly used ones are 5/8″ (16mm) and 13/16″. However, you must make sure that you buy the size according to the cylinder you intend to put it in.
Iridium Spark Plugs:
Iridium spark plugs are harder and their durability is higher than other spark plugs. This plug uses less voltage to generate the electric current due to small electrodes. Iridium spark plugs are available in various sizes but are expensive and hence used rarely. Iridium’s extremely high melting point is perfectly suited to today’s high-temperature engines and excellent acceleration. If the owners manual mentions the use of Iridium spark plug, you must not downgrade to some other metal spark plug. Also, make sure that you use the right spark plug size for your vehicle.
I hope this article has answered all your questions related to spark plugs and various sizes available. Choosing a wrong size spark plug may damage your cylinder and reduce the performance of the engine. In some cases, the wrong size spark plug might not even fit into the cylinder. All these spark plugs – Copper, Platinum, and Iridium are available in various sizes. Make sure you choose the correct size spark plug required by your engine and follow the user manual for usage.