What is the average jaw mouth opening?

Posted by Rob Christensen on 6/22/2010 to Jaw Function, Trismus, and Jaw Therapies

What is the average opening of the mouth and jaw? In an adult? A man? A woman? A child?

Most studies show that the maximum jaw range of motion (ROM) or maximum mouth opening (MMO) is related to body size and height. So men can usually open wider than women, taller people more than shorter people. In studies, MMO for adults has generally been around 50 mm, with a range from 32mm to 77mm. Men can open to about 50-60, and women to 45-55mm.

In a study done in 2008, linked below, a team tried to determine how to assess oral opening function of children. This is difficult because they have such varied body sizes and growth rates. In their study they suggest using the 3 finger test to simply and quickly determine the maximum opening. In this test, patients use their index, middle and ring finger of their non-dominant hand as a general gauge for a range of their opening, but they also note "it is not highly reliable"

Want more info? Click through to the full study:

Clinical measurement of normal maximum mouth opening in children | CRANIO: The Journal of Craniomandibular Practice | Find Articles at BNET



Date: 8/28/2012 10:21:13 AM
my age is 19 height is 4 ft but my mouth opening is 41mm is that average or not ??? please respond me as soon as you can ...
Date: 8/28/2012 10:30:06 AM
Hello as i paste it previously that my age is 19 height 4ft and opening of mouth is 44mm would it be affected if a person used of bittle nuts and would it comes to normal size...???
Date: 8/28/2012 11:38:08 AM
Normal size opening is mostly based on body size. You are quite small, so 41mm may be your normal size opening. However, betel nuts are known to cause trismus (reduced opening) of the mouth. Use the 3-finger test (above) to determine if you are achieving your maximum opening.
Date: 10/4/2012
My mouth opening size is 40mm and my height is 5ft 7 inch, is that average or not? Before I used to chew Gutkha(betel nuts). Thank you
John O'Donnell
Date: 5/9/2013
I can only fit 2 fingers in my mouth I am 6 foot tall and 36 years old
Mike Cook
Date: 5/31/2013
I'm 5'3", and I can open my mouth about 63.5mm; this is above average, yes? I'm also double-jointed; this seems like it'd have an impact on the range of motion for my jaw as well as other parts of my body, yes?
Jack hart
Date: 7/28/2013
Holy crud mine is 76mm ima girl lol im 15 and 5"3 i can almost fit my entire hand in my mouth XD
Date: 6/30/2014
I m 5"1' I can fit only two fingers ie middle ND index in my mouth is that good I m 19 yrs old
Date: 7/2/2014
In general, if you can insert 2-3 fingers between your teeth, you have a reduced opening, but not trismus. Trismus is generally about 2 fingers or less, and is the point where a smaller opening starts to cause functional problems.
Date: 7/14/2014
Hi my age is 19, height is about 5"6 I can open my mouth to 50mm...I'm male..it is normal?
Date: 8/31/2014
Umm... 13 year old girl and I was at the orthodontist and I got a measuring of 60mm
Date: 4/19/2015
I can fit four fingers one fum in my mouth and is it normal for your jaws to grow bigger?
Date: 4/19/2015
I can fit four fingers one fum in my mouth and is it normal for your jaws to grow bigger?
Date: 6/11/2015
I have had to see a TMJ specialist because I was suppose to get my widom teeth out but I couldn't open my mouth enough because the joint had slid out of place, and today I didn't feel that pressure I usually do when I try to open it all the way. I'm 16 and I'm 5'8 what should my mouth measurement be is anyone can tell me? I see the doctor next month but don't wanna wait to see if I'm finally back to normal.
Date: 11/18/2015
62 inches and 3 fingers fit in my mouth vertically which is only 2 and possibly a quarter of his fingers.
ajay Naithani
Date: 5/14/2016
6 foot 180 cm height healthy only 3 fingure is passing in my mouth
Amin Bashir
Date: 9/21/2016
After my dentist visit about 3 weeks ago, I can not open my mouth more than 1 finger size. Can not eat banana, apple or other fruit unless I cut it to grape size bite. What restricts the opening of my mouth, what muscles help to open my mouth and how to fix my problem? amin
ankush alandkar
Date: 12/12/2016
I am 5"4 fit 2 is normal

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