Period Calculator

Period Calculator

Cut down on surprises with our handy period calculator! Use this to help plan ahead for special occasions, vacations, or even ovulation if you’re trying to conceive. Just answer a few short questions and we will generate a customized calendar just for you.

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Tell your friends about the period calculator now.

Answer three easy questions to get started!
Date of your last period?
Today's Date
How long did it last?
8 Days
What’s your usual cycle length?
28 Days
Track Now
Your Calculator
Previous 3 Months
 | 
Next 3 Months
Pre-Period
Period Days
Post Period
Peak Ovulation

Note: This period calculator is only an estimate. Your unique menstrual cycle may vary from these results.

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  • o.b. pro comfort non applicator tampons
    Pre-Period Days

    Your period is on its way and it’s a good idea to start preparing. Get your favorite non-applicator tampons from o.b.® to be ready for it.

    o.b.® Original® Regular
    • For light to moderate flow days
    • This design expands to fit your unique body
    • Protective pocket surrounds your finger while you insert
    Find out more
  • o.b. pro comfort non applicator tampons
    Period Days

    Time to use your o.b.® non-applicator tampons. These are designed to expand all around to fit each unique body type.

    o.b.® Original® Regular
    • For light to moderate flow days
    • This design expands to fit your unique body
    • Protective pocket surrounds your finger while you insert
    Find out more
  • o.b. pro comfort non applicator tampons
    Post-Period Days

    It’s over now, but you might still be spotting a bit, you can keep wearing the o.b.® non-applicator tampons until it ends. Prepare for next month by getting your favorite o.b.® items now so you’re never caught off guard.

    o.b.® Original® Regular
    • For light to moderate flow days
    • This design expands to fit your unique body
    • Protective pocket surrounds your finger while you insert
    Find out more