Prescription snorkel dive mask sizing help page

Unlocking the Perfect Fit: Your Guide to Measuring Your Face for a Scuba/Snorkel Mask

Your Guide to Measuring Your Face for a Scuba/Snorkel Mask (Fit Made Simple)

A great seal = great vision. Use this quick guide to measure your face and choose a mask that fits comfortably, whether you’re buying a prescription snorkel mask, a prescription scuba mask, or any diving mask with prescription lenses.

Tools

1) Soft measuring tape (or rigid ruler)

2) Mirror

3) Pen & paper

scuba diver wearing prescription snorkel mask by oceans optics fron view

Step 1: Head circumference (overall size)

Wrap the tape around the brow line, above the ears—like a comfy hat. Keep it level and snug (not tight).

53–55 cm: Small

56–58 cm: S/M

59–61 cm: M/L

62–64 cm: XL

Tip: If you’re between bands, start with S/M. Choose M/L if you have broader cheekbones or have felt nose-pocket pressure in smaller masks.

Step 2: Eye width

Measure straight across the face at eye level—outer corner to outer corner—keeping the tape or ruler flat (don’t wrap around the curve of your face). This helps gauge frame width and skirt shape for a reliable seal.

Step 3: Nose-to-brow height

Measure from the bottom of the nose to the top of the brow line. This indicates how much vertical space you need so the nose pocket and frame don’t press uncomfortably.

Fit tips that prevent leaks and fog

Do a quick dry-fit at home: place the mask without the strap, inhale lightly through your nose, if it stays for a moment, the skirt shape matches.

Less squinting = fewer leaks. Pick a size that seals with the lightest inhale.

Soft silicone skirts and tempered-glass lenses improve comfort and durability (all our diving masks with prescription lenses are scuba-rated).

Accuracy checklist

1) Measure twice and average your numbers

2) Keep the tape level at the brow line

3) Record in cm (head) and mm/cm (face measurements)

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Want to find your perfect fit?

FREE Find My Mask Quiz

Answer 5 questions and we will recommend you the best fit.

Step 1: Enter your prescription to determine your recommended underwater vision Underwater, light bends differently and can make your usual prescription feel too strong. We lower it slightly to prevent overmagnification and keep your vision clear

Suggested Lens Strength:

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