Contact Lens Power Conversion Chart (Glasses to Contacts)
Short answer: if your glasses power is -4.00 or weaker, order the same power in contacts. Stronger than -4.00, order slightly less minus — glasses sit ~12 mm from your eyes, contacts sit on them, and that gap (vertex distance) changes the effective power. The converter below does the math and snaps the result to powers Mojosee actually stocks (0.00 to -8.00).
Pick a power to convert
Do each eye separately — most prescriptions differ between OD (right) and OS (left). Every Mojosee product page lets you choose a different power per lens.
Conversion chart (nearsighted / minus powers)
| Glasses SPH | Contact power to order | Exact vertex value |
|---|---|---|
| 0.00 to -4.00 | Same as glasses | difference < 0.25 |
| -4.25 | -4.00 | -4.04 |
| -4.50 | -4.25 | -4.27 |
| -4.75 | -4.50 | -4.49 |
| -5.00 | -4.75 | -4.72 |
| -5.25 | -5.00 | -4.94 |
| -5.50 | -5.00 | -5.16 |
| -5.75 | -5.50 | -5.37 |
| -6.00 | -5.50 | -5.59 |
| -6.50 | -6.00 | -6.02 |
| -7.00 | -6.50 | -6.44 |
| -7.50 | -7.00 | -6.86 |
| -8.00 | -7.50 | -7.27 |
| -8.50 | -7.50 | -7.67 |
| -9.00 | -8.00 | -8.07 |
| -9.50 and stronger | beyond our -8.00 range | — |
"Contact power to order" is the exact vertex value rounded to the nearest power Mojosee stocks: 0.25 steps down to -5.00, then 0.50 steps to -8.00.
How to read your glasses prescription
OD / OSOD is your right eye, OS your left. Some prescriptions just say R and L. Convert each eye separately.
SPH (Sphere)The main power — the number this page converts. Minus means nearsighted.
CYL & AXISAstigmatism correction. Small CYL (-0.75 or less) is often fine with spherical lenses; larger values need professional advice — see the astigmatism guide.
PDPupillary distance — used for glasses frames only. You can ignore it for contacts.
Ordering in three steps
- Convert each eye's SPH with the tool above (right and left are usually different).
- On the product page, use the POWER selector — add one lens at your right-eye power and one at your left-eye power. 1 unit = 1 pair of the same power, so mixed-power wearers order two single powers.
- Double-check base curve comfort: our lenses are 8.5–8.7 mm base curve, the most common fit. New to contacts entirely? Start with the first-timer playbook.
What this chart can't do
Plus powers (farsighted): the adjustment runs the opposite direction — a +5.00 in glasses needs more plus in contacts. Confirm with your optometrist.
High astigmatism: spherical colored lenses can't replace toric correction. Ask your eye-care professional about your spherical equivalent before ordering.
Replace an exam: this is a standard optical vertex calculation, not medical advice. Lenses are made from FDA-cleared materials, but fit and eye health still belong to your eye-care professional — more in the safety guide.
FAQ
Why is my contact power weaker than my glasses power?
Because the lens sits 12 mm closer to your eye. The same optical effect needs slightly less power when there's no gap — that's the vertex correction, and it only becomes meaningful past -4.00.
My two eyes have different powers. Can I still order?
Yes — pick each power separately on the product page and add both to cart. Ordering two different powers of the same design is completely normal.
My prescription is from over a year ago. Can I use it?
Most prescriptions are written for 1–2 years. If yours has expired, get a quick re-check first — eyes drift, and a stale power means blurry lenses. More on that in glasses vs contact prescriptions.
Do you sell plano (0.00) lenses?
Yes — every design is available in plano for style-only wear, alongside the prescription range.
What if my converted power lands between two available steps?
Round to the weaker (less minus) power — slightly under-correcting is more comfortable than over-correcting. The converter above already does this for you.
Ready to order? Browse colored contacts for dark eyes or the natural collection — designs carry powers from plano to -8.00, each eye selectable separately.
