With the exception of the Bandit™, the Allergy™ mask (small available) and the FB-1 mask (XL available), there are two sizes available, medium and large. Generally, medium will be suitable for the average size women and large for the average size man. Please use the table below for guidance.
As a rule of thumb mask sizing is as follows;
5′ Small Build – 5’3′ Slight Build = Small
5′ Heavy Build – 5’6′ Average Build = Medium
5’6″ Heavy Build – 6′ Average Build = Large
6′ Heavy Build – 6’+ Average Build = X-Large
A sizing chart is available here
To confirm your size or for us to advise you, please send the following details to customerservices@respro.com
Height:
Weight:
Neck size:
Hat size:
Height:
(most people know their height)
Weight:
(most people know their weight)
Neck Size:
Using piece of cotton or string, measure the circumference around the neck. use a ruler to determine the length of string. This is the neck circumference.
Head size (AKA Hat Size):
Using piece of cotton or string, measure the circumference around the head. use a ruler to determine the length of string. This is the head or hat size circumference.
Respro® Masks are reusable 
Respro® Bulletin Board 
I’m trying to figure out my size. 5 ft, 118 lb, 13-in neck, 5-in face.
Hi,
PERSONAL SIZING
http://respro.com/pg/faqs/mask-sizing-guide
It is important that a mask fits correctly otherwise air will just pass through the gaps and not function how it is intended. Even if it has the best filter; if it is a poor fit it will reduce its ability to filter out the pollutants.
If you do use our website service, we strongly recommend that you send in your details to confirm your sizing. We ask this so that we can ensure you have the correct size and that the mask will be of benefit to you or those who are using it. It is also important for any sizing issues that may arise so we are able to assess and resolve any problems.
Our policy on returns:
If we have advised you of the size for your mask and it is subsequently found to be an incorrect size, then we will exchange the mask.
Please see the following link for sizing assistance and supply the following measurements so we can confirm your size: http://respro.com/pg/faqs/mask-sizing-guide
Height:
Weight:
Neck size:
Head size:
Eye to chin length:
Height:
(most people know their height)
Weight:
(most people know their weight)
Neck Size:
Using piece of cotton or string, measure the circumference around the neck. use a ruler to determine the length of string. This is the neck circumference. Easier still check your shirt size.
Head size (AKA Hat Size):
Using piece of cotton or string, measure the circumference around the head. use a ruler to determine the length of string. This is the head or hat size circumference.
Eye to Chin: REALLY IMPORTANT
Take a piece of string and place it between the eyes on the top of the nose bridge, run the string over the tip of your nose and down to just under the chin. This is the eye to chin length. Please note the curved line and the point to point distance. If you are in doubt then a Passport image would also be useful.