Ovulation Tracking: BBT, LH Tests, and Apps Compared

Knowing when you ovulate can really boost your chances of conceiving. Your fertile window is the 5 days before ovulation plus ovulation day itself. The idea that everyone with a 28-day cycle ovulates on day 14 is often wrong: only about 30% of women ovulate on exactly day 14, and for the rest it varies between days 11 and 21. This guide compares 5 ways to track it.

1. Basal body temperature (BBT):

• How: take your temperature by mouth at the same time every morning, as soon as you wake up and before you get out of bed, using a BBT thermometer that shows tenths of a degree or finer
• Pattern: about 36.1-36.4°C (97-97.5°F) before ovulation, a rise of 0.3-0.5°C (0.5-0.9°F) after it, then 36.4-36.7°C (97.5-98.1°F) until your period
• Pros: cheap (you only need a thermometer), and it CONFIRMS that ovulation happened
• Cons: it shows ovulation only AFTER it has happened, illness and irregular sleep throw it off, and you need about 3 months of charts to see your pattern

2. LH urine tests (ovulation predictor kits):

• How: they detect the LH (luteinizing hormone) surge. Start 2-3 days before you expect to ovulate and test once or twice a day (afternoon is often best)
• Pros: they warn you BEFORE ovulation, which usually happens 12-36 hours after your first positive test, so you can see your most fertile days coming. About 99% accurate at detecting the LH surge itself
• Cons: false positives are common with PCOS (LH can stay high), and you can miss the surge if you don't test often enough. A box holds 7-30 strips, so there is a moderate monthly cost
• Types: drugstores sell both simple strips and digital tests; digital ones are easier to read but cost more

3. Cervical mucus (Billings or Creighton method):

• How: check the toilet paper when you wipe, or check with a clean finger. After your period, mucus usually goes from dry → creamy → milky → clear and stretchy like raw egg white (ovulation is near)
• Pros: free, no equipment, and it teaches you to read your body's signs
• Cons: it is subjective, semen, lubricant, or an infection can change it, and it takes practice to learn

4. Smartwatch or wearable (Oura, Apple Watch, Tempdrop):

• How: measures your temperature and heart rate overnight and uses an algorithm to estimate ovulation
• Pros: no manual logging, works automatically while you sleep, gives you reports looking back
• Cons: expensive, needs 2-3 months to learn your pattern, and is less reliable with irregular cycles

5. Period tracking app:

• How: you log your period dates and symptoms and, in premium versions, BBT or LH results
• Pros: free or low cost, with an easy visual calendar
• Cons: predictions based on dates alone are not very accurate (they assume an average 28-day cycle) and are wrong 30-50% of the time with irregular periods
• TIP: a date-based app plus LH tests is the most practical combination at home

Which method suits whom:

• Regular periods, just starting to try: app + LH tests, a cheap and effective combination
• Irregular periods: a wearable, or daily LH tests + BBT
• PCOS: LH tests can mislead, so ultrasound follicle tracking with your doctor works better
• Trying for a while: see a fertility clinic after 12 months of trying if you are under 35, after 6 months if you are 35 or older, and right away if you are 40 or older

Best timing: your fertile window is 6 days long (the 5 days before ovulation plus ovulation day). Having sex every day or every other day during this window gives you the best odds. Sperm can survive up to 5 days, so having sex as soon as the window opens means sperm are already waiting when the egg is released, which gives fertilization the best chance.

Common myths:

• "Put your legs up after sex": there's no evidence for it. Sperm reach the uterus within minutes anyway
• "Having sex too often uses up the sperm": having sex more than once a day lowers sperm concentration, but it doesn't lower your chances of conceiving
• "It's not happening because I'm stressed": stress can delay ovulation by a few days, but it doesn't cause infertility
• "Getting pregnant takes about a year": many couples conceive much sooner; about 85% of healthy couples conceive within 1 year and 92% within 2. If you are 35 or older, see a doctor after 6 months of trying

Trying to conceive can be stressful, but tracking your cycle gives you a sense of control. There's no perfect method, so pick the one that fits your life and budget. The main rule: start having sex 5 days before ovulation and keep going through ovulation day. The rest is up to your body, your care team, and a little patience.