Cycle Atlas
About Cycle Atlas
Our Purpose
Cycle Atlas helps people map expected menstrual dates as ranges rather than promises. The calculator works without an account, and dates saved with the optional history button remain in this browser only.
We built Cycle Atlas because single-date predictions create false confidence. Biological cycles vary — stress, illness, travel, postpartum changes, perimenopause, and medications all affect timing. A range-first approach reflects this reality honestly.
How It Works
- Enter your last period start date — the first day of full flow, not spotting
- Set your typical cycle length — 21–45 days (default 28)
- Set your period length — 1–10 days (default 5)
- Choose variability — ±1 to ±7 days based on how regular your cycles are
- Get a range — center date ± variability, shown on a calendar and as a three-cycle forecast
All calculations happen in your browser. No data is sent to any server.
Key Principles
- Privacy by design: No accounts, no cloud sync, no health profiles
- Honest uncertainty: Ranges widen with variability; long-range forecasts show accumulating uncertainty
- Medical boundary: Explicit disclaimers separate calendar estimates from health decisions
- Educational focus: FAQ and guides explain how estimates work, not just what they say
Important Limitations
The product is designed for adults who want a clear personal calendar. It does not:
- Identify a medical condition
- Confirm ovulation
- Replace a pregnancy test
- Provide contraception guidance
- Guarantee future cycle timing
Publisher Information
Publisher: Cycle Atlas
Contact: citysoulsound@gmail.com
Website: https://citysoul119.bond/
Cycle Atlas is an independent project. We do not represent any medical institution, healthcare provider, or pharmaceutical company.
Editorial Standards
Our Editorial Policy explains how we present estimates, uncertainty, and health disclaimers. We separate calculation output from medical decisions, identify important limitations, and revise content when calculation methods or safety guidance change.
Privacy & Data
Your cycle entries stay on your device. See our Privacy Policy for full details on local storage, third-party services, and your rights under GDPR and CCPA.