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Healthcare · head to head

Flo vs Sleep Cycle

Flo logo

Flo

Healthcare

Period and cycle tracking app that settled with the US FTC in 2021 over sharing health data with third parties despite promising not to

From
Free
Rated
-
Full reviewWebsite
Sleep Cycle logo

Sleep Cycle

Fitness

Phone based sleep tracking app that uses the microphone or accelerometer to detect sleep phases and wake you in a light sleep window

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Flo flo Health settled with the US FTC in 2021 over allegations it shared sensitive health data, including pregnancy and menstruation details, with Facebook, Google and other third parties despite telling users the data would stay private, a fact directly relevant to how much a user should trust current privacy claims without independently checking the published policy.; Sleep Cycle sleep stage detection is inferred from sound and motion rather than measured with dedicated physiological sensors, so accuracy is lower than a ring or watch based tracker like Oura.
  • They diverge on capability: Flo covers Cycle and ovulation tracking, Sleep Cycle covers Sound and motion sleep analysis.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which Flo and Sleep Cycle actually diverge.

Attributes where Flo and Sleep Cycle differ
AttributeFloSleep Cycle
PlatformsiOS, Android, WebiOS, Android
CategoryHealthcareFitness

Identical on both: starting price (Free), pricing model (Free with a Premium subscription), free tier (Yes), user rating (Not yet rated).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Flo

  • Cycle and ovulation tracking
  • Pregnancy mode
  • Anonymous Mode
  • Symptom and mood logging
  • Expert content library
  • Community and forums

Only in Sleep Cycle

  • Sound and motion sleep analysis
  • Smart alarm
  • Sleep quality trends
  • Snore and sleep talk recording
  • Sleep aid sounds and stories
  • Apple Health and wearable integration

What people use each for

The jobs each tool is most often brought in to do.

Flo

  • Someone tracking cycle and ovulation who wants to weigh app convenience against the sensitivity of the data being loggednot Sleep Cycle
  • A user in a jurisdiction with legal risk around reproductive health data who wants to check Anonymous Mode and current data sharing policy before logging pregnancy or fertility attemptsnot Sleep Cycle
  • A buyer wanting to compare Flo directly against Clue on published data practices before choosing which app to trust with this informationnot Sleep Cycle
  • Someone who wants pregnancy tracking content alongside cycle tracking in one app rather than switching apps mid-pregnancynot Sleep Cycle

Sleep Cycle

  • Someone who wants sleep tracking without buying a ring or watch, using a phone they already ownnot Flo
  • A person who struggles with grogginess from alarms and wants to be woken during a light sleep window insteadnot Flo
  • Someone who wants to check whether they snore or talk in their sleep, which requires the Premium subscriptionnot Flo
  • A buyer comparing upfront cost against Oura or a smartwatch before deciding whether hardware-free tracking is good enoughnot Flo

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Flo

  • Flo Health settled with the US FTC in 2021 over allegations it shared sensitive health data, including pregnancy and menstruation details, with Facebook, Google and other third parties despite telling users the data would stay private, a fact directly relevant to how much a user should trust current privacy claims without independently checking the published policy.
  • Reproductive health data, including logged periods, fertility attempts and pregnancy status, has been the subject of law enforcement data requests in some jurisdictions following changes to reproductive rights law, and cloud-stored logs are a real category of exposure regardless of a vendors intentions.
  • Anonymous Mode, the privacy feature introduced after the settlement, is a setting that must be checked and understood rather than assumed, and its exact scope and default status should be verified in the current privacy policy rather than taken from marketing copy.
  • Free tier predictions rely on self-reported symptom data and general population models, so accuracy for irregular cycles or specific medical conditions is limited compared with clinical tracking.
  • The subscription auto-renews and, like most mobile subscriptions, must be cancelled through app store account settings rather than inside the app itself.

Sleep Cycle

  • Sleep stage detection is inferred from sound and motion rather than measured with dedicated physiological sensors, so accuracy is lower than a ring or watch based tracker like Oura.
  • The app needs to run overnight with the microphone active or the phone on the mattress, which raises its own privacy consideration for anyone uncomfortable with a phone microphone recording an entire room overnight.
  • Most of the features that make the sleep data actionable, detailed trends and snore analysis, are behind the Premium subscription rather than included free.
  • Battery drain overnight from continuous microphone or motion sensing is a real practical issue for anyone who also wants to use the phone as a normal alarm without charging it.
  • Detection can be disrupted by a shared bed, a partners movement or snoring, or ambient household noise, all of which reduce accuracy for the primary user.

Pricing, plan by plan

Flo

Free
  • Flo Premium$11.99/month
    • Free tier covers core cycle tracking, predictions and symptom logging
    • Premium adds deeper personalised insights and expert content, around $11.99 a month
    • Annual and lifetime purchase options typically offered at a lower effective rate

Sleep Cycle

Free
  • Sleep Cycle Premium$39.99/year
    • Basic sleep tracking and the smart alarm are free, no hardware required
    • Premium unlocks detailed trends, snore recording playback and most sleep sounds
    • Annual Premium commonly around $39.99, with a higher effective rate if billed monthly

Which should you pick?

Choose Flo if

  • You need cycle and ovulation tracking.
  • You want to start without paying.
  • You work on iOS, Android, Web.
  • You also want pregnancy mode.
Flo review

Choose Sleep Cycle if

  • You need sound and motion sleep analysis.
  • You want to start without paying.
  • You work on iOS, Android.
  • You also want smart alarm.
Sleep Cycle review

Questions people ask

Is Flo or Sleep Cycle better?
Neither clearly leads. Flo starts at Free and Sleep Cycle at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Flo or Sleep Cycle?
Flo starts at Free and Sleep Cycle at Free.
Does Flo or Sleep Cycle run on more platforms?
Flo runs on iOS, Android, Web. Sleep Cycle runs on iOS, Android.
Can I use Flo for free?
Both have a free tier, so you can try either at no cost before committing.
What is Flo best used for?
Flo is most often used for someone tracking cycle and ovulation who wants to weigh app convenience against the sensitivity of the data being logged, a user in a jurisdiction with legal risk around reproductive health data who wants to check anonymous mode and current data sharing policy before logging pregnancy or fertility attempts, a buyer wanting to compare flo directly against clue on published data practices before choosing which app to trust with this information, someone who wants pregnancy tracking content alongside cycle tracking in one app rather than switching apps mid-pregnancy. Of those, someone tracking cycle and ovulation who wants to weigh app convenience against the sensitivity of the data being logged and a user in a jurisdiction with legal risk around reproductive health data who wants to check anonymous mode and current data sharing policy before logging pregnancy or fertility attempts are not what Sleep Cycle is typically brought in for.
What can Flo do that Sleep Cycle cannot?
Flo covers Cycle and ovulation tracking, Pregnancy mode, Anonymous Mode, Symptom and mood logging. Sleep Cycle covers Sound and motion sleep analysis, Smart alarm, Sleep quality trends, Snore and sleep talk recording.

Answered from the vendors’ own pages

Flo: What happened with the FTC in 2021?

The US FTC alleged Flo Health shared sensitive health data, including pregnancy and menstruation details, with third parties like Facebook and Google despite promising to keep it private. Flo settled without admitting liability, agreeing to obtain consent for future sharing and to an independent privacy review.

Sleep Cycle: Do I need to buy any hardware for Sleep Cycle?

No. It uses your phones microphone or accelerometer, placed on the nightstand or mattress, with no separate device to buy.

Flo: What is Anonymous Mode?

A privacy setting Flo states disconnects entered health data from an identifiable profile. Check the current app and privacy policy for whether it is on by default or must be turned on manually, since this affects what data is linked to your identity.

Sleep Cycle: Is Sleep Cycle free?

Basic tracking and the smart alarm are free. Detailed trends, snore recording and most sleep sounds require Sleep Cycle Premium.

Flo: Is Flo free?

Core cycle tracking and predictions are free. Deeper personalised insights and expert content require Flo Premium.

Sleep Cycle: How accurate is phone based sleep tracking compared with a ring or watch?

Less accurate, since it infers sleep stages from sound and motion rather than measuring heart rate or temperature directly, which dedicated wearables like Oura do.

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