Designed for men

Stop guessing how she feels.

Know Her is the period tracker app for boyfriends and husbands. See her phase, mood and energy every day — no medical knowledge needed.

Start Free

Download on the App Store Get it on Google Play
Know Her period tracker app — home screen widget showing her cycle phase for men

Luteal?

Ovulation?

Follicular?

Make it simple.

Everything you need. Nothing you don't.

Know Her period tracker — home screen widget showing her cycle phase

Everything at a glance

See her current and next phases directly from your home screen widget. Two widget sizes. Instant updates.

Know Her period tracker — daily dashboard showing mood, energy and phase for the male partner

Your relationship dashboard

See what's happening now and how to support her. Get personalized guidance for every phase of her cycle.

Know Her period tracker — calendar view for boyfriends and husbands

Mood and energy, day by day

Follow signals that help explain how she may be feeling — from vitality and emotional sensitivity to irritability and physical comfort.

Know Her period tracker — daily conditions and mood indicators for men

Stay one step ahead

Get the full picture of her calendar and see what's coming next. Prepare in advance and show up at the right moments.

Just what you need. No more, no less.

5-second setup

The quickest onboarding. No account, no forms, no medical information. Answer 2 questions and you're in.

Reliable from day one

Built on 612K cycles and data from 19 million women across the world. Continuously improves its predictions the more you use it.

Designed for simplicity

No relationship advice — just clear understanding of your partner. Know what matters, when it matters.

Personal notes & reminders

Set reminders for anything — now or in the future — in her cycle. Plans, thoughts, or personal notes brought back to you later.

Your notifications, your rules

Only relevant updates: phase changes, insights, and your own notes. Turn them on or off anytime. Full control, always.

100% private & offline

Nothing leaves your device. No account, no cloud, no sync. Protected with Face ID and biometrics. Your data stays only on your phone.

Real questions. Honest answers.

Most period trackers are built for women — full of symptoms, charts, and medical data that doesn't mean much to a male partner. Know Her is different. It was built by men, for men who want to understand her cycle without the noise. No relationship coaching scripts, no medical jargon she'd need to explain. Just the essentials: her current phase, her energy, what she might need from you. Simple enough to check in under a second — right from your home screen widget.
Very. Know Her is built around a simple calendar that shows her entire cycle at a glance — current phase, upcoming phases, and important indicators like her mood, fertility and energy. Every phase has its own colour and a short visual cue so you always know what to expect, not just today but across the weeks ahead. No charts to interpret, no terminology to look up. Open the app, see where she is, know what that means for you. That's it.
Know Her learns from her specifically. Every confirmed period makes it more accurate — adjusting to her actual rhythm instead of assuming a generic 28-day cycle. The predictions are grounded in large-scale research: studies covering 19 million women (Flo Health, Scientific Reports, 2024) and 612,000 real cycles (Natural Cycles, npj Digital Medicine, 2019). The longer you use it, the more it's built around her.
You don't need to. Just enter the date her last period started — Know Her handles the rest. It starts with research-backed averages and refines its predictions automatically every cycle. No setup complexity, no biology degree required.
No. Know Her works entirely from information you enter yourself — no account for her, nothing to install, nothing to share. You just need the date her last period started. She doesn't even need to know you're using it — though she might appreciate that you care enough to try.
Yes. Any day on the calendar can have a personal note — whatever makes sense to you. A reminder to plan something special, a night you want to remember, something you noticed about her mood. It's your private space, completely free-form. If you want to be reminded of a note on a specific day, just turn on the notification for it. Everything is written by you, seen only by you, and stays on your device.
Yes. Add the Know Her widget to your home screen and see her current phase and days remaining at a glance — no need to open the app. When her cycle is always visible, it becomes second nature to stay in sync with her.
Yes. Know Her sends you an alert the day before her phase changes, so you're never caught off guard. Notifications are on by default — you can turn them off anytime in settings if you prefer to check manually.
Yes. Everything stays on your phone — no account, no cloud, no sync, nothing to leak. You can lock the app with Face ID or biometrics for extra privacy on top of that.
You get 14 days of full access, completely free. After that, Know Her runs on a simple subscription — monthly or annual. Cancel anytime directly in your App Store settings.
Yes. Settings → Reset clears your data so you can start over with new information at any time.
English, Portuguese, Spanish, Italian, French, and German — the app automatically matches your device's language.
No. Know Her is designed to help you understand and plan around her cycle — it's not a medical device, diagnostic tool, or method of contraception. For health decisions, always consult a healthcare professional.

Not just the best — the best value on the market.

Free

All features included. Everything you need to support her.

14 days
Start Free
  • Daily mood, energy and fertility indicators
  • Widget for instant updates
  • Get notified when phases change
  • Smarter predictions over time
  • View upcoming phases in advance
  • Set personal notes and reminders
  • Fully private, offline and biometric-protected
Monthly

Full access, month to month. Cancel anytime.

$2.99/mo
Start Free
  • Daily mood, energy and fertility indicators
  • Widget for instant updates
  • Get notified when phases change
  • Smarter predictions over time
  • View upcoming phases in advance
  • Set personal notes and reminders
  • Fully private, offline and biometric-protected
Most Popular
Annual

Just $1.67/mo. Save 44% vs monthly.

$19.99/yr
Start Free
  • Daily mood, energy and fertility indicators
  • Widget for instant updates
  • Get notified when phases change
  • Smarter predictions over time
  • View upcoming phases in advance
  • Set personal notes and reminders
  • Fully private, offline and biometric-protected

Available on
iOS & Android.

Free for 14 days.

No commitment. Cancel anytime.

Download on the App Store
Send us a message