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Project N95's Guide to Mask Sizing and Fit

We have compiled a guide to help you find the right fitting N95, KN95, KF94, or other high filtration mask for your face size. Below you will find a chart comparing size by mask type, a guide to determining your face size, a list of common fit issues, instructions for checking if your masks fit, and masks we recommend for different face sizes, shapes, and fit issues.

How to use this guide

  • Review the size chart and face size guide to determine your size.
  • Learn how to evaluate the fit of your mask using the seal test.
  • Read our mask guides to find masks for specific face sizes.
  • Read the size guidance on product pages.
  • Filter by size on the category pages.
  • Read product reviews when available.
  • Help others find masks that fit by leaving a product review. If you are comfortable with it, provide face size, shape, and any features that have made it hard for you to find a mask in the past. This can help others find a mask that fits well.

Mask Size Comparison Chart

Use this chart to understand how different mask sizes are shown on the Project N95 site based on mask type and to understand which mask size to choose based on your face size.

Face Size N95 KN95 KF94 Other High Filtration Masks
Kids Ages 2-5 N/A Pre-k Extra Small (XS) Pre-K
Kids Ages 6+ N/A Kids/Small Small (S) Kids
Small/Petite S or S/M S or S/M Medium (M) S or S/M
Medium S/M or M/L S/M or M/L Large (L) S/M or M/L
Large M/L or L/XL M/L or L/XL Large (L) M/L or L/XL
Extra Large L/XL or XL L/XL or XL Extra Large (XL) L/XL or XL

BNX KN95 Size Chart

Face Size BNX KN95
Kids Ages 6+ Small
Small/Petite Medium
Medium Large
Large Large

How to Determine Your Face Size

We have put together this handy guide to determine your face size. You can determine your face size by using the measurement system below. We have also included some quick tips below this guide to help you figure out your fit if you don't have a tape measure handy.

Quick Tips that don't require a tape measure
  • Check the Project N95 website if you have purchased from us in the past to see what size your mask is classified as.
How to Measure
  • Width - measure the horizontal width of the face from the widest point of the cheekbone.
  • Height - measure from the bridge of the nose, to beneath the chin.
Mask Face Measurement Width Mask Face Measurement Height

Face Size Measurement Chart

This chart is based on the NIOSH Bivariate Panel. Normally these measurements are performed using calipers. If you are measuring yourself at home you may not get a perfect measurement. Please use these measurements as a basic guide and in conjunction with the tips provided above for determining face size.

Face Size Size Number Face Height (mm) Face Width (mm)
Small/Petite 1 98.5 to 108.5 mm 120.5 to 132.5 mm
Small/Petite 2 98.5 to 108.5 mm 132.5 to 144.5 mm
Small/Petite 3 108.5 to 118.5 mm 120.5 to 132.5 mm
Medium 4 108.5 to 118.5 mm 132.5 to 144.5 mm
Medium 5 98.5 to 118.5 mm 144.5 to 158.5 mm
Medium 6 118.5 to 138.5 mm 120.5 to 134.5 mm
Medium 7 118.5 to 128.5 mm 134.5 to 146.5 mm
Large (L) 8 118.5 to 128.5 mm 146.5 to 158.5 mm
Large (L) 9 128.5 to 138.5 mm 134.5 to 146.5 mm
Extra Large (XL) 10 128.5 to 138.5 mm 146.5 to 158.5 mm

How do you know if your mask fits?

Below is a basic guide on how to perform a seal check. Performing this check can help you to understand if your mask fits properly. This is not a comprehensive guide, or a substitute for professional fitting for medical employees or where available for the public.

For a more comprehensive guide please check out our full seal test article.

Step 1: Put your mask on.

Step 2: Adjust the mask to seal it to your face.

Step 3: Feel for air flow around the mask. Cup your hands around the top of your mask and feel for air on your hands. Repeat with the bottom portion of your mask.

If you do not feel the air from the exhalations, your mask fits properly and you are ready to go.

Step 4: Adjust the mask’s placement if needed. Move the mask towards the area where you felt air leaking and press down lightly to readjust the mask. Then reperform the seal check from Step 3 until you no longer feel air escaping from your mask.

Step 5: If you are still feeling air escape from your mask you can try crisscrossing the straps to get a better seal. Again reperform the seal check from Step 3 until you no longer feel air escaping from your mask.

Step 6: Try a new or different mask if you are still not able to get a proper fit after performing the seal check.