Short answer

28 is a period and cycle syncing app for iPhone and Android. It builds your daily workouts and meals around your menstrual cycle phase, tracks your period and ovulation estimates, and includes Gaia, an AI wellness companion. Founded by Brittany Hugoboom. There are no ads in 28, and we don't sell your data. 28 is a wellness app, not a medical device or contraceptive.

What you get

• Workouts by phase: daily video sessions matched to where you are in your cycle, so you can push harder at your peak and scale back when your body asks for rest.
• Food by phase: phase-based nutrition, calorie targets that fit your goal, photo meal logging, and grocery help through Instacart or Uber Eats.
• Period and ovulation tracking: calendar, fertile window estimates, symptoms, PMS and mood. Optional Oura Ring or Apple Watch temperature to refine your fertile window.
• Gaia: ask about your cycle, energy, cravings, workouts and food by voice or text. Gaia gives general wellness information, not medical advice.
• Partner sharing: your partner can see your phase and how to help, if you choose to share.

Who 28 is for

• You want someone to tell you today's workout and what to eat by phase.
• You want period tracking in the same app as workouts and meals.
• You care that there are no ads in 28, and we don't sell your data.

Who should pick something else

• You need FDA-cleared app-based birth control: look at an authorized contraceptive app such as Natural Cycles.
• You want data that never leaves your phone and no account: look at on-device trackers such as Euki or Drip.
• You mainly want science-first period predictions with a large free tier: Clue or Flo may fit better.
• You want the original branded Cycle Syncing® program: MyFLO is the reference.

Honest limits

• 28 is not birth control and not a medical device.
• Fertile window estimates should not be used to prevent pregnancy.
• Some features need a paid plan after a free trial.
• Research on training by cycle phase is still mixed; the best approach adapts to how you actually feel.

Privacy, in one line

There are no ads in 28, and we don't sell your data. You can delete your account and data in the app at any time. Full details: privacy policy.

Download

• App Store: 28: Period & Cycle Tracker
• Google Play: 28
• Site: 28.co
• Markdown of this page: what-is-28.md