✅ Usage Instructions & Helpful Notes

How the Pregnancy Calculator works

• Primary method (recommended): enter the first day of your last menstrual period (LMP) and your average cycle length. The calculator uses Naegle’s rule (LMP + 280 days) adjusted for your cycle length to estimate your Estimated Due Date (EDD).

• Optional conception date: if you know the exact conception or IVF transfer date, select “Yes” and enter that date. The calculator will then estimate EDD as conception + 266 days (about 38 weeks), which is commonly used when conception is known.

• Conception estimate: if you only enter LMP, conception is estimated as LMP + 14 days (approximate ovulation day).

• Weeks & days pregnant: shows how many weeks and days have passed since LMP.

• Trimester: approximate trimester is shown (1st, 2nd, 3rd) based on weeks since LMP.

• Progress: a percentage of the standard 40-week pregnancy (LMP-based).

• Countdown: days remaining until EDD (or days past if overdue).

Important notes & disclaimers

• This calculator provides estimates only and is not medical advice. For clinical confirmation, dating, or decisions — rely on an ultrasound or consult your healthcare provider.

• Early ultrasounds (typically done in the first trimester) often give the most accurate due date.

• Cycle length, irregular periods, breastfeeding, recent hormonal contraceptive use, or fertility treatments can affect accuracy.

• The tool does not store your data — all calculations run locally in your browser for privacy.

Quick examples

• If your LMP is Jan 1, 2025 and cycle is 28 days: EDD ≈ Oct 8, 2025 (LMP + 280 days).

• If you know conception happened on Feb 1, 2025: EDD ≈ Oct 24, 2025 (conception + 266 days).

FAQs

1. Which date is best to use — LMP or conception?
   LMP is most commonly used. If conception is certain (IVF or known ovulation), use conception date for a more accurate estimate.

2. Can this detect multiple pregnancy or complications?
   No — only an ultrasound and medical professional can provide clinical information.

3. Is EDD exact?
   No — only ~5% of births occur on the exact due date; the date is an estimate for planning.

4. Does it handle irregular cycles?
   You can adjust the cycle length field, but if your cycles are highly irregular an early ultrasound is recommended for dating.