One-signal calculator

Period calculator for partner planning

Use a known period start, current bleeding signal, period end, or late signal to estimate the next useful window.

Run the calculator
Window-based outputConfidence shown upfrontDashboard-ready result
Start with one signal
What did she mention?
When?

Selected Jul 10

How it works

Calculate the next window

This is a planning estimate. Save the result to keep improving it with each new signal.

  1. Enter a date
  2. Pick the signal type
  3. Save or revise after the next update

Product proof

A real dashboard, not a 28-day guess.

Roostercal turns one sparse signal into a row you can act on: next window, fertile window, confidence, quick logging, reminders, and calendar export.

Open the dashboard
ChickNowNext periodMove
BealutealJul 14-18Reduce friction
Quick logBleedingStartedLateNote
Reminder plan2-day heads-up, expected start, late check-in
Export .ics

Use cases

Built for the real sparse-data workflow

  • Replace rough calendar math
  • Compare next period and fertile windows
  • Know when a forecast is still learning

Pricing

One row free. More with Pro.

Free saves one active row and includes data export. Pro is $7/mo or $49/yr for additional rows, automatic check-ins, a live calendar, weekly planning, and forecast history.

Start free

FAQ

Practical answers

Is a 28-day cycle assumed?

The public calculator starts with a simple estimate. The app becomes more personalized as logs accumulate.

Is this contraception advice?

No. Fertile-window output is for planning context only, not contraception or pregnancy prevention.