Planner inputs
Example data table
| Example | LMP | Cycle | Luteal | Estimated ovulation | Fertile window | Estimated delivery |
|---|---|---|---|---|---|---|
| A Regular cycle | 2026-02-01 | 28 | 14 | 2026-02-15 | 2026-02-10 → 2026-02-16 | 2026-11-08 |
| B Variable cycle | 2026-02-01 | 28 (min 26, max 32) | 14 | 2026-02-13 → 2026-02-19 | 2026-02-08 → 2026-02-20 | 2026-11-08 |
Formula used
- Estimated ovulation (cycle method): Ovulation = LMP + (Cycle length − Luteal length).
- Fertile window: From 5 days before ovulation to 1 day after.
- Likely conception range: From 2 days before ovulation to 1 day after.
- Estimated delivery date: LMP + 280 days, or Ovulation/Conception + 266 days.
- Implantation window: Roughly 6–10 days after ovulation.
How to use this calculator
- Choose the planning method that matches the date you know.
- Enter your date(s) and cycle details, if applicable.
- Click Calculate plan to view your fertile window.
- Use the download buttons to save a CSV or PDF report.
- Track cycles over time to refine your accuracy.
FAQs
It’s an estimate based on typical sperm survival and ovulation timing. Tracking LH tests, cervical mucus, or basal temperature can narrow the window for many people.
Enter Cycle min and Cycle max to create a planning range. The tool will widen ovulation and fertile window dates to help cover variation.
Ovulation usually happens a set number of days before the next period. Using a luteal estimate helps place ovulation more realistically than assuming day 14 for everyone.
Yes. Choose “Known ovulation date” to calculate the fertile window, likely conception range, and estimated delivery date from that reference.
Usually not. Many people aim for every 1–2 days during the fertile window. This approach helps cover timing uncertainty without focusing on a single date.
Early testing is often estimated around 9–10 days after ovulation, but results vary. Waiting until the missed period date can reduce false negatives.
Select “Target delivery date” and enter the date you’re aiming for. The calculator back-calculates estimated ovulation and suggests a corresponding fertile window.
No. It’s for planning and learning. If you have health concerns, irregular bleeding, or difficulty conceiving, consult a qualified clinician for personalized advice.