1 of 13 · Today
One ring, one glance.
Where you are, what has passed and what is likely next. Splash floats round the ring, and dozes off at night.
How estimates workYour cycle
stays with you.
A free period and ovulation tracker with no account and no subscription. Your cycle stays on your phone by default, and anything you back up or share is encrypted first.
What we can and can’t see
Only about 13% of cycles are exactly 28 days.1 So Splash shows a window, and how sure it is.
Drag the ring, or use the arrow keys. Watch the window move.
Day 9Follicular phase
Next period likely in 18 to 22 days
- Period
- Fertile window (estimated)
- Next period window
An illustration with an example cycle, not a prediction.
And it shows its working.
After four full cycles, Insights replays its own predictions on your past cycles, using only what came before each one, and shows how close each guess landed. It tells you how predictable your cycle has been, not a promise about the next one.
How predictions workExample: how predictable a cycle has been
7 of the last 8 period predictions landed within 2 days of the real start.
1. Bull JR et al. Real-world menstrual cycle characteristics of more than 600,000 menstrual cycles. npj Digital Medicine, 2019. ↩
Everything, on one phone.
Log in two taps, see a range, not a guess, and find Splash on your Lock Screen, Home Screen and wrist.
2 of 13 · Daily log
Log it in a couple of taps.
Flow, pain, mood, sleep, tests and notes, each with a severity. Search for a symptom, or type or say it and Splash files it.
All features3 of 13 · Calendar
Hearts that mark your fertile window.
Period days in coral, the estimated fertile window as blue hearts, and dashed circles for what Splash expects, so a guess never looks like a fact.
Trying to conceive4 of 13 · Insights
Your cycle, in a sentence.
Your average cycle in plain words, where it sits in the typical 21 to 35 day range, and a next-period window that narrows as you log.
Insights5 of 13 · Lock Screen
Timers on your Lock Screen.
Pain relief, mini pill and contraction timers count down on the Lock Screen and in the Dynamic Island, with neutral wording if you prefer. Cycle widgets sit above the clock.
How Lock Screen timers work6 of 13 · Widgets
Your day, on the Home Screen.
Small and medium widgets show your cycle day, fertile window and next period. On Android, “Your cycle” and “Quick log” widgets and long-press shortcuts do the same.
Apps and widgets7 of 13 · Apple Watch
A ring on your wrist.
Start or end a period, log flow, symptoms and mood, or breathe, right from Apple Watch. Complications keep your day on the watch face.
Apple Watch and apps8 of 13 · Partner
Let them in, a little.
Your partner sees only what you switch on: a countdown, your phase and kind ideas for today. They can tap “On it”. Stop sharing whenever you like.
Partner sharing9 of 13 · Pregnancy
From trying to pregnant, the NHS way.
A positive test turns on pregnancy mode, dated from your last period, a scan or an IVF or IUI transfer. Your NHS journey, a one-tap “Baby moving less?” button, a contraction timer, kick counter and hospital bag.
Pregnancy mode10 of 13 · Doctor report
Bring months to a ten-minute appointment.
A tidy summary of cycles, symptoms and notes for your GP, your blood results kept beside it, and questions to ask. Free, like the rest.
Doctor report11 of 13 · Privacy
Locked, even on the phone.
Face ID or Touch ID with a PIN as backup, encryption on the phone itself, discreet mode, and a decoy PIN that opens a harmless, empty Splash.
Privacy features12 of 13 · Library
165 short reads, read aloud.
Based on NHS, NICE, FSRH and RCOG guidance, and checked again against their sources in October 2026. Offline, and Splash reads them aloud.
Browse the library13 of 13 · Switch & sync
Bring your history. Keep your health apps.
Import from Flo, Clue, Apple Health, drip and more, read on your phone. Splash works with Apple Health on iPhone and Health Connect on Android, for temperature from Apple Watch, Samsung Health, Fitbit or Oura.
How to switch from FloGet Splash, freeOpens in your browser. Nothing to sign up for.
Ovulation, worked out from your signs.
Splash starts from your own cycles, then reads the signs you log. Every estimate says how sure it is, Estimated, Likely or Confirmed, and shows how it got there.
- LH testsLow, High and Peak strips, or numbers from a reader
- Cervical mucusThe peak day, from dry to egg-white
- Basal temperatureA coverline drawn for you, and the shift above it
- Wrist and skin temperatureApple Watch, or wearables through Health Connect
- PdG testsA sign ovulation has happened
Trying? The dashboard shows your best days to try, a days-past-ovulation count to a sensible test day, the implantation window, a preconception checklist, and a gentle NICE-based prompt for when to see your GP. With PCOS or irregular cycles, more than one LH rise stays possible and windows widen to match.
Ovulation and trying to conceiveEstimatedEstimated ovulation, around day 15
LikelyLikely ovulation, day 15
ConfirmedOvulation confirmed, day 15
How we worked it out
- Your last 6 cycles put ovulation around day 14 to 16
- No tests logged yet this cycle, so the window stays wide
Best days to try: about day 13 to 15
How we worked it out
- Peak LH on day 14: ovulation usually follows in 1 to 2 days
- Egg-white mucus peaked on day 14
- Your earlier High readings on days 12 and 13 opened the window
Best days to try: today and yesterday
How we worked it out
- Temperature stayed above your coverline from day 16
- Peak LH on day 14 and the mucus peak agree
- PdG tests stayed positive on days 20 to 22
8 days past ovulation · test from Sat 7 Nov
LH High · PeakEgg-white mucusBest days to tryExample cycle, made-up data
Ovulation and fertile-window dates are estimates to help you understand your cycle. Splash is not contraception.
A decoy PIN, a breathing shark, twelve themes.
12 themes, light and dark.
Seafoam, Moon jelly, Sandy shore, Night and more. Nothing about it shouts "period tracker".
Breathe with Splash.
4-4-4-4, sleepy 4-7-8 or calm 5-5, with haptics and an ocean sound.
A decoy PIN.
A second PIN opens a harmless, empty Splash. You can set it to wipe the real data.
Discreet mode.
Neutral notifications, and sensitive words swapped for sea emoji on screen.
Splash grows a reef.
Log or take a breath and he collects shells. Place what you like and he naps in the clam. Miss a few days and he just naps. Nothing to buy.
Private by how it's built, not by a promise.
If you don't make an account, nothing about your cycle reaches us. If you do, we only hold a locked copy, encrypted with AES-GCM-256 on your phone, and we don't have the key.
Only you
Your phone
- Periods, symptoms, moods
- Love life, notes, tests
- Photos and your PIN
- The vault key
We can see this
Our server
- A locked box of ciphertext
- Your email, if you sign up
- Sync times and sizes
- Notification text (neutral by default)
Only if you share
Your partner
- Only the categories you tick
- Decrypted on their phone
- Never your PIN or photos
- Revoke in one tap
The full "what we can see" list · PIN, Face ID or fingerprint, decoy and wipe · Security
iPhone, Apple Watch, Android, and every browser.
- iPhoneWorks with Apple Health, plus Home Screen and Lock Screen widgets that show your day at a glance.
- Apple WatchA cycle ring on your wrist. Start or end a period, log flow, symptoms and mood, or breathe. Complications for your watch face.
- Android“Your cycle” and “Quick log” widgets, long-press shortcuts, and Health Connect, for temperature from apps like Samsung Health, Fitbit and Oura.
- Any browserOpen Splash in any browser and add it to your home screen. Same Splash, free.
Every feature, free.
Splash is free, with no premium tier and no data selling. Including the things other apps charge for:
- Partner sharing
- Doctor report
- Pregnancy mode
- Perimenopause mode
- Full library
- Patterns and correlations
How it’s free · All 54 features · Switch from Flo · Switch from Clue
Answers, without the app.
165 short reads based on NHS, NICE, FSRH and RCOG guidance, and 19 free calculators that work right here in your browser.
Browse the libraryFair questions.
Can I bring my history from Flo or Clue?
Yes. Export from your old app and import the file in Splash. It is read on your phone, and nothing is replaced.
Is it really free?
Splash is free, with no premium tier and no data selling.
Do I have to make an account?
No. Open it and start logging. An account is only needed if you want encrypted sync or to share with someone.
How does Splash work out ovulation?
It starts from your own cycle history, then updates as you log LH tests, cervical mucus, temperature or PdG tests. Each estimate is labelled Estimated, Likely or Confirmed, with how it was worked out.
Is there an iPhone, Apple Watch or Android app?
Splash is on Google Play for Android, with apps for iPhone and Apple Watch, plus widgets. The web app also installs from your browser and works offline.
Can I use it as contraception?
No. Splash is not contraception and not a medical device. Predictions are estimates.
Dip a toe in.
Made for one person first, and named after a teddy shark from Newquay aquarium. Open it in your browser today, with no sign-up. Or get it on Google Play.
All the ways to get it · Why Splash exists
Splash is not contraception and not a medical device. Predictions are estimates. If you're avoiding pregnancy, use a method that is.