Instructions on How to Size a Mouthguard

Your mouthguard is an important piece of safety equipment in many sports. Football, boxing and many martial arts require it, while it remains optional but recommended in many others. A mouthguard cushions the impact of a blow to the chin. This protects your teeth from breaking under the impact, and helps reduce the amount of kinetic energy that transfers upward into your brain. Sizing a mouthguard is not intuitive, but it is easy once you know how. These instructions are for basic mouthguards. For more expensive and complex models, consult with the manufacturer's instructions.

A mouthguard cushions the impact of a blow to the chin. (Image: fastfun23/iStock/Getty Images)

Step 1

Put the mouthguard in your mouth. Close your mouth normally and focus on the back of your mouth, near your molars. If you feel the mouthguard is pressing against your jaw hinge, or triggering your gag reflex, remove and trim the guard at the two open ends. Most brands of mouthguards have lines marking the ends for best results when trimming.

Step 2

Repeat step one until the mouthguard is comfortable in terms of how it fills your mouth.

Step 3

Pour one cup of water into the glass bowl, then heat for two minutes on high in a microwave.

Step 4

Drop the mouthguard in the hot water for a count of 10. Fish it out using your spoon, or chopsticks.

Step 5

Shake the mouthguard once to remove any excess hot water, then place it in your mouth. Bite down firmly for a slow count of 20.

Step 6

Remove the mouthguard and drop it in the ice water for two minutes. This will set the newly fitted mouthguard permanently to match your mouth and teeth.

Step 7

Pull the mouthguard out of the ice water. Dry it off and put it away.

Things You'll Need

  • Mouthguard

  • Scissors

  • Glass bowl

  • Microwave

  • Spoon or chopsticks

  • Ice water


Rinse your mouthguard before and after use and periodically clean it in cool soapy water.


Test the temperature of the mouthguard with the tip of your finger before putting it in your mouth to mold to your teeth. It should be comfortably hot.

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