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 study abstract:




Date 8/28/2012 10:21:00 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 10:30:00 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 11:38:00 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

Suyash sagar

Date 8/18/2017

I m 5 foot 8 inches and I can fit only 3 fingers in my mouth, and I am 27 years old


Date 9/29/2017

Well I'm 6 feet, and I beat the record with a 90mm open range, which I know is above the average. XP


Date 10/11/2017

Hello last week I had a surgery of my wisdom tooth . Dat cause infection so doctor took out. My age is 28 n after 2 weeks when I try to open the mouth I feel it's not open as before surgery so it is common or if not so what should I do ? Plz give suggestions

donald charron

Date 10/12/2017

38 year old male lomited opening 5 feet 125 pounds no teeth not able to fit more than my thumb space between top and botom jaw mri have shown nothing only that in each mri done it states minimal moth opening and i suspect that with the minimal opening they are not able to verify that anything is wrong


Date 11/28/2017

My mouth open only 32mm hardly if I can do mouth exercise trice a day because I m tmj problem so please tell me best muscles relaxant which has no side effect and my height normally 4and half fit ,I use daily voltral tab 50mg ,whenever medicine stop again same mouth closing problem began ,please help me to give best and because I m tmj from 6years

Roman Escobedo

Date 12/6/2017

I'm so confused. I'm doing research on what the radius and the diameter of an average mouth than can open. ANYBODY got some suggestions?


Date 1/3/2018

I just got an accident and now only 2 fingers can fil in my mouth and m 5.7 tall


Date 1/29/2018

no one finds this humorous in any what way


Date 2/24/2018

MY SELF PRASANTA Hello last week I had a surgery of my impacted wisdom tooth . Dat cause infection so doctor took out. My age is 30 yrs after 2 weeks when I try to open the mouth I feel it's not open as before surgery so it is common or if not so what should I do ? Plz give suggestions


Date 8/22/2018

This comment was recently deleted, so here it goes again: Wow. Fascinating stuff. Couldn’t resist the temptation to conduct an experiment of my own. Started a few weeks ago with three spicy Italian sausages (beginning without buns). Each measured approximately 30mm in diameter (about 90mm total). I train my jaw twice a day, and after the first week jumped up to four sausages. The week after, four sausages including buns. While I am aware that some compression is bound to happen, I estimate but this fourth week, I’ve been training with five sausages and buns, an estimated 150mm! Accidentally swallowed an entire sausage whole, so I would highly reccomend against recreating this experiment without sufficient supervision. Any recommendations as to how I can more accurately measure my opening? My significant other and I are curious for an accurate reading, and aren’t quite sure the “Sausage Method” is the most efficient. I am roughly 5 ft., weigh 98.7 lb, and have never entered a hot dog eating contesting (but am considering it now if anyone recommends it). Any input is much appreciated!

Add Comment