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Flo vs Natural Cycles: catalog facts
Flo	Natural Cycles
Best for: People tracking their menstrual cycle, ovulation or pregnancy on a phone	Best for: People looking for hormone-free birth control or fertility tracking
Free + paid options Free to download, with a paid premium subscription.	Paid Subscription service; prices are not listed on the homepage.
Android, iOS	Android, iOS
Tracks periods, ovulation and pregnancy in one app Symptom logging alongside cycle dates	FDA-cleared as a birth control app Covers contraception, pregnancy planning, postpartum and perimenopause All 3 strengths for Natural Cycles FDA-cleared as a birth control app Covers contraception, pregnancy planning, postpartum and perimenopause Works with an overnight band and other compatible devices
Proprietary service that handles sensitive health data Some features require a paid subscription	Less effective than an IUD, with 93% typical-use effectiveness Requires regular temperature or biomarker measurements All 3 limitations for Natural Cycles Less effective than an IUD, with 93% typical-use effectiveness Requires regular temperature or biomarker measurements Pricing not listed on the homepage
Downloadable app, Hosted service	Downloadable app
Not open source	Not open source
License not stated	License not stated
Not stated if an account is needed	Account needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Sources for Flo flo.health play.google.com/store/apps/details apps.apple.com/us/app/flo-cycle-period-tracker/id1038369065 Catalog checked September 23, 2026	Official website Full listing and sources Sources for Natural Cycles naturalcycles.com play.google.com/store/apps/details apps.apple.com/us/app/natural-cycles-fertility-app/id765535… Catalog checked September 24, 2026

“Not stated” means we have not confirmed it. Features can vary by device and plan.