Contact lens prescription does differ from spectacle prescription, mainly due to the distance between the spectacle and your eyes.

For those with spectacle prescription less than -4.00 D, the difference is insignificant. Patients can choose to wear either the same prescription or slightly lower. Spectacle prescription of -4.00D above, the difference with contact lens prescription will become more significant.

The chart below, is a conversion chart of spectacle prescription to contact lens prescription.

(-) Minus prescription is refer for short sighted or myopia. (+) Plus precription is refer for long sighted or hyperopia.

Besides that, a simple calculation can be done to determine your contact lens prescription (as the diagram below):

If you need any further understanding or clarification about your contact lens prescription, feel free to email or seek consultation from your eyecare practitioner.

32 thoughts on “Contact Lens Prescription”

  1. Hi, I don’t quite know what to do now … I have calculated my -3 prescription from your chart to be -2.9D but what do I do with that?

    My eyeglass prescription is

    OD -3.00 -0.25 110
    OS -3.00 -5.0 123
    OD +1.75
    OS +1.75

    Can you tell me what the contact lense prescription would be for ordering contacts on-line?

    Thank you.

  2. Hi Jennifer,

    According to theoretical calculation, your contact lens prescription would be
    OD -2.90
    OS -2.90/-4.40×120
    However, as contact lens prescription is -0.25 jump, hence your estimated contact lens prescription would be
    OD -2.75
    OS -2.75/-4.00×120
    Medium Add

    This is an estimated prescription and vision may varies for every individual. For more accurate contact lens prescription, I would suggest you visit your optician for a thorough contact lens fitting.

    Thank you.

  3. Hello. Im also having a bit of trouble converting my glasses presciption
    Sphere/ cylinder/ axis
    Right eye: -4.50. -1.00 005
    Left eye : -4.50. -0.50 180

    Thank you in advance!

  4. Hi Rachel,

    According to theoretical calculation, your contact lens prescription will be
    Right eye (RE) -4.25/-0.75×180
    Left eye (LE) -4.25

    This is an estimated prescription and vision may varies for every individual. For more accurate contact lens prescription, I would suggest you visit your optician for a thorough contact lens fitting.

    Thank you.

  5. Hi, how would I work this formula in reverse? I have my contact lens prescription, but I want to convert it to a prescription for glasses.

    Both my left and right eyes are -2.50

  6. Hi Denise,

    Basically, by working reverse formula, you would not get your actual glasses prescription.
    If you just need a glasses to see, need not have sharp vision, you can have prescription of -2.75.

    Prefer not to have an eye examination? Then, I would suggest you bring your old or current glasses to your optician, then will be able to know your prescription via checking the lenses.

    Thank you.

  7. contact lens :

    od -325 – 125 x 075
    os -325 – 050 x 090
    pd 64

    Can some please tell me what this converts to in eye glasses , both 12 mm and 14 mm ?

  8. Hi Karma,

    I would suggest you refer to your optician for your actual glasses prescription.
    Otherwise, for 12mm, you may use back the exact same prescription as your contact lenses.
    Thank you.

  9. Hi my glasses RX is -2.00 -1.25 ax 003
    -1.75 -1.25 ax 012 what would be my contact RX? Thanks so much

  10. If I order contact lenses as power of -8.0, bc 8.60 and dia 14.2 how can I convert this to eyeglasses?

  11. Hi Erika,

    You would not get an accurate glasses power by converting from your contact lenses power.
    Approximately, your glasses power will be -9.00D.
    Thank you.

  12. R-3.00 sph-0.75 ax 010 BC 8.7
    L-3.25 sph-0.75 ax 180 BC 8.7
    Can you convert this from contacts to glasses for me please

  13. Can someone help me with converting my contacts to glasses?
    Left eye
    Base curve Median
    Diameter 14.5

    Right eye
    ase curve Median
    Diameter 14.5

  14. My glasses prescription is

    RIght: sph -2.50 cyl -1.25 axis 180
    Left: sph -2.25 cyl -1.00 axis 170

    What would be my toric contact prescription? Does the sph and cyl stay the same or lower by 0.25? Please help!!!

  15. Hi my Doctor undercorrected my contacts from -6.50 to -6.00 because my work involves microscopy. Currently -6.00 contacts work for me as I don’t drive. I only noticed a little blurriness for power point presentations when I sit far. I was wondering if I were to get new glasses…If I should get -650 or -675 Rx? Thankyou for your time.

  16. I’m having trouble converting my glasses because I only see large numbers here . I have a small prescription
    Of only SPH +0.50 in my left eye and SPH +0.75 in my right how do I turn this into a contact prescription .

  17. Hey, my prescription would be
    OD: -3.00 / -0.75 / 140
    OS: -2.00 / -0.75 / 40

    So what would my contact prescription be?

  18. Hi dear. Sorry for the late reply.
    It is always better to consult your doctor for your driving prescription.

    Nonetheless, you can have an extra pair of glasses that you wear while using your contact lenses for clearer distance vision.
    Thank you.

  19. Hello, I’m still confused on the formula and would like to know my prescription, I’m in need of contacts.
    My left eye follows as
    -1.50 C
    -1.75 A

    My right eye is:
    -1.25 C
    -1.50 A
    Could you please help

  20. If your C means Cylinder and your A means Axis. Then your contact lens prescription will be as below.
    LE -4.25/-1.25×180
    RE -3.75/-1.25×150

  21. This is only an estimated power.
    Vision may varies from one individual to others. For more accurate prescription, please refer to your regular optician/optometrist/doctor, for a trial fit.

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