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Full Face Respirator Mask Sizing

Choosing the Proper Size of Respirator Mask

3M Respirators Side by Side size Comparison
3M Full Face Masks. Small, Medium & Large

3M Full Face Respirator Sizing

Designed to protect sensitive membranes in the eyes, nose, throat and mouth, 3M 6800 series full face respirators come in 3 sizes, Small, Medium and Large. Each of the 3 masks are all the same size except for the rubber seal which is mounted to the product. The rubber face seal dictates the size of each of the masks. Below you will find a listing of the 3 sizes, and some approximate measurements and statistics for each mask.

3M states conservatively that the Medium size respirator mask (full and half face) fit 80% of the population. Most people that fit the Large respirator sizes, will know this due to past experience with items like glasses, hats, helmets or other items that end up not fitting on their heads. While it's important to perform a proper fit test, the majority of our customers will be quite happy with the medium size respirator.

Respirator Rules of Thumb

Leave the area immediately and then check your mask and/or filters if:
  • If you can taste it
  • If you can smell it
  • If you can feel it
  • If you feel drowsy, dizzy, confused, or nauseous
  • If it stings, irritates or causes discharge (runny noses, etc..)
  • If something feels or seems wrong

It is important to note that not all chemicals cause side effects. Some are odorless, tasteless, and have no symptoms other than injury or death.


Common Questions about Respirators

3M Full Face Respirator Comparison


Medium 3M 6800 Medium Full Face Mask

3M 6800 Medium Respirator (Grey)
3M 6800 Medium Mask
80% of users
The 3M 6800 Medium respirator fits 80% of the population, and I would argue that most individuals that fit the large respirator, can also fit this respirator. The dimensions of this mask from top to bottom are 7.5 inches with an opening of 5-1/2 inches. From side to side, the width of the opening is roughly 5.5 inches, with the opening being about 4-1/4 inches. In our office here at Enviro Safety, everyone "fits" the medium size mask, with one individual leaning towards the Large mask. None of our staff fit the small respirator.

Large 3M 6900 Large Full Face Mask

3M 6900 Large Respirator (Dark Grey)
3M 6900 Large Mask
15% of users
The 3M 6900 Large Full face respirator here is distinguished by the dark grey rubber face seal. The mask openings top to bottom are 7-3/4 inches with an open space of 5-3/4 inches making the mask slightly larger in opening. From side to side the measurements are 5.5 inches with an opening of 4-1/2 inches. When held side to side, the large mask spreads open slightly more, but the differences are subtle. Not like the size differential you see with the small sized mask.

Small 3M 6700 Small Full Face Mask

3M 6700 Small Respirator (Light Grey)
3M 6700 Small Mask
5% of users
The 3M 6700 Small Full face respirator here is distinguished by the light grey rubber face seal. The small version of the mask is suitable for individuals of very small head/face size.

Fit testing your mask

Fit testing of respirators should always be performed with the appropriate fit testing materials. Fit testing kits can be found on our website. Fit testing involves wearing a respirator inside of a hood, and spraying a mist into the hood. The subject, wearing the respirator and filters then breaths in certain patterns and reports if he or she can detect the mist. By doing a proper fit test one can be assured that the mask fits properly. However, fit testing does not indicate that the mask or filters used are effective in the contaminated area. Choosing the right cartridge or filter is critical for any application, and a certified site audit must be completed in order to properly protect individuals from harm.

Fit test kits come in bitter or sweet versions - and are a requirement by OSHA for many work environments where employees are required to wear breathing protection in hazardous or potentially hazardous environments.

Filters and Cartridges

Filters and cartridges for masks should be chosen depending upon the environment and the measured hazards present. These filters and cartridges can be found on our website in our filters and cartridges section


The following is a way to quickly determine if a full face mask or half face mask is fit properly to an individual. This is not accepted by OSHA or any formal agency - so use at your own risk. However, when presented with a situation where fit testing is not available and the only choice is not testing, or doing a quick test like this, you may wish to consider this. Of course, in any situation where the fumes, chemicals or particles may damage health or risk life, a professional fit testing is a must.

Quick, unofficial fit test*

  1. Don the respirator as you normally would.
  2. Tighten the straps.
  3. Place your hands gently over the filter mount holes. It's important to NOT to press in.
  4. Breath in. You should find it impossible to breath.
    1. if the mask leaks around your face - choose another mask.
    2. if the mask does not leak - you may have an adequate fit.

*Utilize this procedure at your own risk! This procedure does not substitute in any way for a proper fit test and a site evaluation for chemical levels and quantities

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