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Natural Cycles vs Flo: catalog facts
Natural Cycles	Flo
Best for: People looking for hormone-free birth control or fertility tracking	Best for: People tracking their menstrual cycle, ovulation or pregnancy on a phone
Paid Subscription service; prices are not listed on the homepage.	Free + paid options Free to download, with a paid premium subscription.
Android, iOS	Android, iOS
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	Tracks periods, ovulation and pregnancy in one app Symptom logging alongside cycle dates
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	Proprietary service that handles sensitive health data Some features require a paid subscription
Downloadable app	Downloadable app, Hosted service
Not open source	Not open source
License not stated	License not stated
Account needed	Not stated if an account is needed
Not stated if it works offline	Not stated if it works offline
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	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

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