Period Forecaster, Early Pregnancy Test Calculator

Use your ovulation date to get a more precise forecast of when your next period will start - in many cases the exact period start date even if your menstrual cycle varies! Also shows if your period is late, and, optionally, timelines when to take home pregnancy tests.

This period calculator can be very accurate but you need to have ovulated in this cycle (more below), and the forecast is for your next menstruation start date, not future predictions beyond that.

Calculate Next Period Based On:


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Period Calculator Fields

Luteal Phase Length - Luteal Phase is the number of days between ovulation and when your next period starts. If you're a logged in MyMonthlyCycles member, your luteal phase setting in My Preferences fills in.

How to calculate Luteal Phase Length?

With MyMonthlyCycles's Enhanced Fertility Tools, your average luteal phase length is calculated based on your ovulation tracking, and you can update preferences for retrieval on this calculator.

You can also use Mymonthlycycles luteal phase calculator, which can calculate using a previous menstrual cycle stats.

Average Menstrual Cycle Length - This is the average number of days your cycle lasts. If you are a logged in member, your cycle length fills in based on your period tracking calendar.

Ovulation Date - Enter the date you ovulated during your current menstrual cycle.

How do I know when I've ovulated?

There are several ways to help determine when you ovulated:

  1. Basal Body Temperature (BBT)

    BBT, your waking temperature, can detect when you've ovulated. BBT can not be used to determine in advance when you will ovulate during your cycle. That's because BBT is a retrospective marker of ovulation -- good news for determining when you did ovulate.

    After a thermal shift upward (of typically 4/10ths of a degree), which remains elevated for several days, ovulation has generally already occurred. If your chart's pattern shows the sustained BBT rise, ovulation most likely occurred the day before the rise. The amount of the thermal shift can vary, which is why tracking and charting your BBT over several months helps you see your patterns.

    Track BBT free at MyMonthlyCycles. With Enhanced Fertility, chart BBT to help identify ovulation, and more!

  2. Observing Cervical Fluid (CF)

    Cervical Fluid changes throughout your fertility cycle, going from dry and almost non-existent following your period, to a creamier consistency as you progress through your follicular phase. As you near ovulation, CF generally becomes more abundant with a slippery texture (EWCM - egg white cervical mucus). EWCM is alkaline, providing the ideal hosting and transport environment for sperm.

    EWCM is also your body's way of telling you ovulation is about to occur. Immediately following ovulation, cervical fluid decreases and starts to dry up again. When this happens, you've likely just ovulated!

    Daily CF Tracker free at MyMonthlyCycles. With Enhanced Fertility, track all cervical signs and see your ovulation pattern charts!

  3. Monitors, Scopes, OPKs

    Yet another way to determine when you ovulate is by using fertility monitors, ovulation microscopes, and/or ovulation prediction tests kits (OPKs).

    For example, OPKs detect the LH surge in your urine, which happens about 24-36 hours before ovulation, thereby giving you excellent advance notice that ovulation is about to occur and, therefore, a simple marker of when you ovulate (i.e. 24-36 hours after the LH surge).

  4. Secondary Ovulation Indicators

    Secondary indicators are often used with the primary fertility detectors above, but not stand-alone.

    Mittelschmerz - Some women experience mittelschmerz: pain that occurs during ovulation in the lower abdomen, on the same side as the ovary that ovulates that month's egg. If you're a mittleschmerzer, it's your body announcement: I'm ovulating!

    Cervical Firmness, Position, Opening - The cervix changes throughout your menstrual cycle; at ovulation time, it's generally softer, higher, and more open, making it easier for sperm to travel through it.

To pinpoint when you ovulate, you might want to use several, or all, of the above ovulation detection methods. If, for example, your cervical mucus is EWCM, indicating ovulation is about to occur, watch your BBT chart closely for several days to determine if your BBT has risen and stays elevated; Similarly, if your ovulation prediction test detects the LH surge and you are simultaneously observing EWCM, each of these two primary ovulation signs validates the other.

Disclaimer: We make no guarantee that your period, fertile days, and/or when home pregnancy tests might be effective, will occur on the predicted dates, since each person's menstrual and fertility cycles can vary in any given monthly cycle for a variety of reasons. All information provided herein is for informational purposes only. It is not intended as a substitute for advice provided by a medical doctor or qualified healthcare provider. No guarantee is made about the accuracy, completeness, or relevance of the information contained herein.