Lumen CycleIt stays on the device
Everything you log lives in a database on your phone. No account to create, no server to breach — because there is no server.
No account. No servers. No uploads.Your cycle,
Your cycle,
on your phone.
Nowhere else.
Lumen Cycle predicts your next period and learns your rhythm as you log — and it does all of it on the device in your hand.
- 0Servers
- 0Accounts
- 0Trackers
Your cycle
Log a period,
get a prediction
Next period6 September
in 18 days± 2 days
19of 28
Cycle day
Averaged from your last 4 cycles.
High confidence28-day cycle
Three promises
A short list, because a longer one would mean we were padding it.
It learns your actual cycle
Predictions start from a typical 28 days and move towards your real average. The app shows how confident it is rather than pretending to be certain.
Reminders, not nagging
One optional local notification before your period is due. Scheduled by your phone, delivered by your phone.
One tap is the whole input
Tap the day your period started. From two logged periods on, the app has a real cycle length to work with, and everything else follows from it.
On hormonal contraception? Turn the fertile window off. It suppresses ovulation, so showing a fertility estimate would imply a signal the app has no basis for.
August 2026
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How it goes
Log a day
Tap the date your period started on the calendar. That is the entire input.
Watch it learn
After two periods it has a real cycle length, and the confidence bar starts climbing from a guess towards something earned.
Keep or export
Your history never leaves unless you send it. Export writes a plain JSON file and hands it to you.
Not a medical device
Lumen Cycle is a record-keeping and estimation tool. It cannot tell you whether you are pregnant, and it should not be used to prevent pregnancy. Cycles move with stress, illness, travel and sleep — things no app can see.