Appy · 2 min
Cycle-tracking apps, what they're good at, what they're not
3 sections · 2 min read
What are cycle-tracking apps genuinely good at?
Cycle-tracking apps are excellent at one thing: giving you a record over time. If you track period start dates consistently for 6 months, you can spot patterns, cycle length variability, pain days, mood days, PMS patterns, that no single memory can.
That record is gold at a doctor's appointment. It answers the question 'how long are your cycles?' with data instead of guessing.
What do cycle-tracking apps get wrong?
The 'fertile window' and -day predictions are mathematical guesses based on your past cycle lengths. They are reasonable in textbook 28-day cycles and fairly unreliable in PMOS, irregular cycles, or any cycle under major stress. Relying on them for contraception is risky without confirmation methods.
Some apps have sold user data to advertisers. Others have been subpoenaed in legal contexts. Read the privacy policy, seriously, before you entrust an app with years of intimate data.
How reliable are cycle-tracking apps if you're trying to conceive?
The best-evidenced predictor of in a home setting is urine testing ( predictor kits), ideally paired with cervical mucus observation. Basal body temperature confirms after it happens, useful for pattern-building, not for 'now' timing.
Use the app to record what you observe. Do not use the app's predictions alone.
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Reviewed by clinicians
Authored and reviewed by clinicians from the founding team. Information only, not personalised medical advice.