For Those Who Care

The cycle phases in your calendar.

Updates itself · Without an app

1Set the last period and cycle length 2Generate a personalized calendar 3See the cycle, day by day
Last period
Apr 6 16 days ago
Cycle length
28 days Most: 25–32
Works with Apple Calendar, Google Calendar, Outlook. No account.
After subscribing

How it looks in the calendar.

Today would be Day 7 — Regeneration
The weeks ahead Month ▾
REGENERATION
Menstruation
Ease into stillness
Day 7 of 28
WHAT'S HAPPENING
A fuller daily context appears here.
DID YOU KNOW?
A short biological context sits here.
WHAT TO NOTICE
SOMETHING TO CONSIDER
Context that mirrors the live daily page.
Adjust your cycle
Phase entries

Each cycle phase shows as a calm all-day entry across the weeks.

Daily Page

Tap an entry: short context, body signs, and one small thing to notice today.

Rhythm of Tides appears as its own subscribed calendar inside Apple Calendar, Google Calendar, or Outlook. You can show, hide, or remove it anytime.

The cycle
Four phases. Four rhythms.

Every cycle moves through four distinct phases. Each one has its own biology, its own energy, and its own emotional landscape. These are the days when certain things land easier — and others, harder.

1–5
6–13
14–16
17–28
Regeneration
Menstruation · Days 1–5
Estrogen and progesterone drop to their lowest. The body resets. Energy is limited — these are days that ask for rest.
Rise
Follicular · Days 6–13
Estrogen climbs steadily. Mood, focus, and drive can lift. A natural window for plans, decisions, and momentum.
Peak
Ovulation · Days 14–16
Estrogen peaks, a brief testosterone rise. Openness and confidence often surface — a short window for connection.
Shift
Luteal · Days 17–28
Progesterone rises while serotonin can dip. Sensitivity grows — small things may feel bigger than they are.
Born out of a need
A real problem, by the numbers.

Cycle awareness changes how the days are read — but most tracking apps get ignored after a few weeks. Where the calendar lives, awareness lives.

84%
say cycle symptoms disrupt close relationships
Wallace et al. 2025
~30d
average abandonment time for tracking apps
Symul et al., npj Digital Medicine 2019
80%
of partners can't identify cycle length
INTIMINA / YouGov 2021
60%
say cycle awareness improves daily decisions
Flo Health 2023
The content
Grounded in science.

Every phase description and daily note is built on peer-reviewed research. No clinical claims, no fertility prediction — orientation, not diagnosis.

npj Digital Medicine
Real-world menstrual cycle characteristics of 600,000+ cycles
Bull et al., 2019
Endotext / NIH
The Normal Menstrual Cycle and Control of Ovulation
Reed & Carr, 2018
Psychoneuroendocrinology
How to study the menstrual cycle: tools & recommendations
Schmalenberger et al., 2021
npj Digital Medicine
Menstrual health status via mobile apps for fertility awareness
Symul et al., 2019
Learn more
Want to understand the cycle better?

What cycle awareness actually means, where it lands across the four phases, and why this isn't another tracking app — in one short guide.

We got some tips for you
Questions
Good to know
What exactly do I get? +
A private subscribed calendar that adds the four cycle phases as all-day entries — with a short daily note for each day. It appears as its own calendar inside Apple Calendar, Google Calendar, or Outlook. No app to install, no account to create, no sign-up of any kind.
Who is this for? +
Anyone who wants the cycle visible where they already look. People tracking their own cycle, partners, family, close friends. It works the same either way — the calendar doesn't care whose cycle it is.
Which calendars work? +
Any calendar that supports ICS/WebCal: Google Calendar, Apple Calendar, Outlook, and most others.
What if the cycle shifts? +
Every calendar event includes a "Shift Cycle" link. One tap, enter the new start date — the feed recalibrates automatically.
How accurate is this? +
Orientation, not prediction. Cycles vary naturally. Rhythm of Tides gives a frame for the days, not a forecast.
Is this a fertility tracker? +
No. It's an orientation tool — designed for awareness, not for conception planning or contraception.
What about privacy? +
No account needed, no email needed, no sign-up of any kind — your calendar uses a private link, generated from an anonymous token. We never see who you are or what's in your calendar.
The cycle, made visible.
Three steps. Two minutes. No app to install, no account needed.
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