< Cycle Calculators

Missed Period Calculator

If you have missed your period due to cycle issues, menstrual suppression, perimenopause or pregnancy, calculate the correlation to missed cycles, periods, and flow days during the skipped time span.

This calculator is also more advanced than our late period calculator (released 2 decades ago!): if you are late, but have not missed a cycle, use both your average and longest cycles to compare lateness; And, see the point at which you will have missed an entire cycle.

Member? Login and cycle info fills in: last period, cycle lengths...

Number of days your period usually lasts

Copyright bInfinity Web, Inc. All rights reserved.

Helpful Member Reports/Charts:

IMPORTANT NOTE: If your period is later than usual, or your cycle and/or periods are changing or becoming irregular, always talk with your gynecologist or healthcare provider who can evaluate based on your specific cycle history.

About Missed Period Calculator

Use this calculator to find out where you are in your cycle: are you late, or have you completely skipped one or more cycles? Enter the fields below to calculate.

Entry Fields

Member Note: You can override any value filled in from your cycle tracking history.

Last Period Start Date: - Enter the date your last period started. If you are a logged in member, this is filled in from your period tracking history.

Average Cycle Length: - Enter your average cycle length: how many days your cycle usually lasts. If you're a member and logged in, this auto-calculated value is filled in.

Longest cycle length: - This is an optional field. Enter your longest cycle. For example, if your cycles usually range from 27 to 31 days, enter 31.

For logged in members, your auto-calculated longest cycle fills in, which takes into account your Max Cycle Exclusion Rule, if specified.

Period Flow: - Enter how many days your period usually lasts, used to calculated total missed flow days. For members, this field is retrieved from your App Prefs.

Today's Date: - Fill in your date if it differs from that displayed.

What Causes a Missed Period?

There are a variety of reasons for missing one or more periods, called secondary amenorrhea, many outlined below.

  • Pregnancy - Every month the uterine lining thickens in preparation for pregnancy. If not pregnant, the endometrial lining is shed, resulting in menstruation. If pregnant, the lining is retained, continuing to thicken to provide a nurturing environment into which the embryo will attach and grow: baby's first nursery!

    Ovulation does not occur once pregnant; where there's no ovulation, no period follows.

  • Rapid weight change - Significant weight loss in a short amount of time can cause periods to be delayed or to stop, primarily due to lack of calories which, in turn, can cause a hormonal imbalance that interferes with ovulation.

    Being overweight can cause delayed or skipped periods due to excessive levels of estrogen, which causes a hormonal imbalance impacting ovulation. It's also associated with PCOS (see below) in adolescence.

  • Stress - Unusual and sustained stress can cause one's body to shut down reproductively such that ovulation does not occur, and therefore no periods.

  • Thyroid Disorder - The thyroid hormone helps regulate the menstrual cycle. Both hyperthyroidism, where the thyroid is overactive, producing too much thyroxine, and hypothyroidism, where too little is produced, can cause missed periods.

  • Polycystic Ovary Syndrome (PCOS) causes a hormonal imbalance, which interfere with the ability to ovulate, resulting in irregular or missed periods.

  • Premature Ovarian Failure (POF) - Sometimes called Premature Menopause, POF is a condition in which ovarian function slows markedly or ceases prior to age 40. The most common symptom is irregular or absent menstrual periods.

  • Perimenopause - the transitional period of several years before menopause. Hormone level fluctuations (gradual decrease in estrogen) often result in irregular menstrual cycles. It is not unusual to miss several cycles, resume menses as before, and repeat in a similar or different cycle pattern.

  • Hormonal Birth Control - When taken continuously, hormonal birth control is a way to completely stop one's periods and is also referred to as menstrual suppression. Like any prescribed medication, always discuss with your healthcare provider if menstrual suppression is a safe option for you.

    Some also experience missed periods when coming off of hormonal birth control, which can take several months to return.

What's Difference Between Late and Missed Period?

Generally a late period is one that starts a few days later than your usual period. For example, if your cycle is usually 27 to 29 days in length, and you have a cycle that starts in 32 days, that period is a late period, but not a missed period because it did start a few days later than usual.

A missed period, on the other hand, is a period that is completely skipped. So if your cycle length ranges from 25 to 28 days, and you get to cycle day 56 or later with no period, you've completely skipped a cycle. In fact, in this example, on day 56 you've skpped 2 cycles: the first that did not start on day 28, and the second which still had not started 28 days later on day 56.

Your doctor or other trusted health resources may have different definitions for a late or missed cycle. Sometimes these terms are used synonymously. On pregnancy test instructions missed period typically means the day your period should start.

For the purpose of this calculator, the distinction outlined above is used. Further, the calculator considers the first cycle that does not start as being late but not missed until one complete cycle has passed, enabling comparisons to your longest cycle, if provided, and more.

How Can I Track Irregular Cycles in MyMonthlyCycles?

From its inception in 2003, MyMonthlyCycles was designed to handle irregular cycles via its flexible one click/tap period calendar or full menstrual tracking calendar. With either, simply indicate the start day of your period and the rest, as they say (sort of), is your cycle history!

Look back on any cycle and easily determine its cycle length via the Cycle Day (CD) counter in the day preceding the next cycle start.

How Can I Chart Irregular Cycles in MyMonthlyCycles?

MyMonthlyCycles has dozens of Reports and Charts that provide concise details on all aspects of your cycles.

Cycle History is particularly useful to review cycle lengths, indicating shorter or longer than usual cycles and periods.

Disclaimer: The information provided on this calculator is for educational purposes only. It is not medical advice and is not intended as a substitute for medical advice. You should not use this information for self-diagnosis or for treating a health problem or disease. You should never disregard medical advice or delay seeking medical advice or treatment because of something you have read herein. If you have any questions whatsoever about your medical health or believe you have a medical problem or disease, you should contact your medical doctor or healthcare provider.