Can I Measure Segment Height by Myself?


Getting the perfect pair of glasses isn’t just about frames and lenses—it’s about nailing the details like segment height. Wondering if you can measure it yourself? Spoiler alert: You absolutely can! Let’s dive into the materials you’ll need and a step-by-step guide to ensure your eyewear fits like a dream.

Understanding Segment Height:

Segment height is a crucial measurement in crafting lined or standard bifocal lenses. Why does it matter? Well, it determines the lens proportions. Too high, and you’re stuck mostly with the lower magnifying prescription; too low, and your reader lens won’t be useful without some head gymnastics.


Materials You’ll Need:

Good news—measuring segment height solo is a breeze and requires no fancy equipment. If you’ve got a pair of bifocals, you’re all set. Simply slip them on, grab a ruler with millimeter markings, and measure (or have a helpful friend assist) the distance from the bottom of one lens to the top of your bottom eyelid. That measurement? Your segment height. Now, armed with this intel, you’re ready to input the details when ordering prescription bifocals online. Easy, right?


Mirror: A full-length mirror
works best for accuracy.


Ruler or Measuring Tape:
Precision is part of the game.


Marker or Sticky Notes:
For marking the spot.

Pair-of-glasses-for-reference-to measure-segment-height

Your Favorite Pair of Glasses:
A reference point for perfection.


Step-by-Step Process

Step 1: Set the Stage
Position yourself in a well-lit room with your mirror and materials at the ready.

Step 2: Put on Your Glasses
Wear your pair of glasses. This will be your guide to getting the perfect fit.

Step 3: Find Your Pupils
Look straight ahead into the mirror and mark the center of each pupil with a small dot or sticky note. These marks are your starting points.

Step 4: Measure Down
Using your ruler or measuring tape, measure downward from each pupil mark to the bottom of the lens. This distance is your segment height. Attention: the measurement refers to the bottom of the lens, not the frame.

Step 5: Record and Repeat
Note down the segment height for each eye. For accuracy, repeat the process a couple of times to ensure consistency.

Step 6: Double-Check for Symmetry
Check that the segment heights for both eyes are symmetrical. If not, make slight adjustments until you achieve balance.

And…Voila! You’ve just conquered the art of measuring segment height. Armed with this knowledge, your next pair of glasses is destined to provide not just clear vision but also that perfect, tailored fit. Say goodbye to guesswork and hello to eyewear that truly reflects you. Happy measuring!

Measuring the SEGMENT HEIGHT

Watch Video



Don’t let the importance of the segment height measurement dissuade you from measuring it yourself. For one thing, it’s not an exact science. If you like a bigger magnifying surface at the bottom, you can bump the measurement up by a millimeter or two; if want more of your standard corrective prescription to take up the lens, you simply shave off one or two millimeters. As a rule of thumb, however, the segment height shouldn’t exceed the halfway point on your frame.

If you prefer not to measure segment height by yourself, you can leave that portion of the prescription order form blank. If you do, your new lenses will be made with the standard segment height that corresponds to the frame style you’ve selected. So if you’re comfortable with the standard height of a bifocal, you don’t have to measure segment height at all. If you’d rather adjust the location of that bifocal line, provide a segment height and the optics lab will customize your bifocals to your liking.

If you have any questions about measuring segment height or any other concerns, please feel free to contact us!

  1. Jane says:

    What about segment height for progressive lenses?

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