Pregnancy Due Date Calculator
Based on the first day of your last period, this calculator estimates your due date using Naegele’s Rule — the standard method used worldwide. It also shows your current gestational age, trimester, and key fetal milestones.
📅 Enter your LMP
📊 Your Pregnancy at a Glance
Due Date
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Gestational Age
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weeks
Trimester
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Days Pregnant
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Days Until Due
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Est. Conception
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LMP
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Due Date
📈 Pregnancy Timeline
Milestones
Today
Due Date
🏁 Key Milestones
🌍 International Standards
Pregnancy dating standards vary slightly by country. Below are common reference points used by leading health organizations worldwide.
🇺🇸 USA (ACOG) Due date = LMP + 280 days. Full term: 39–40 weeks.
🇬🇧 UK (NHS) Due date = LMP + 280 days. Routine dating scan at 12 weeks.
🇪🇺 WHO 280 days from LMP. Preterm: <37 wks; Term: 37–42 wks.
🇦🇺 Australia 280 days from LMP. Early ultrasound to confirm dates.
🇨🇦 Canada 280 days from LMP. Dating ultrasound recommended.
🇮🇳 India 280 days from LMP. Government guidelines align with WHO.
🇿🇦 South Africa 280 days from LMP. Routine antenatal care.
🇧🇷 Brazil 280 days from LMP. SUS guidelines follow WHO.
⚕️ Naegele’s Rule (LMP + 280 days) is the global standard. Always confirm with a healthcare provider.
❓ Frequently Asked Questions
How accurate is the LMP due date?
The LMP method is most accurate when cycles are regular (28 days). It can be off by 1–2 weeks; an early ultrasound provides the most precise dating.
What if my cycle is longer or shorter than 28 days?
Naegele’s Rule assumes a 28‑day cycle. For longer cycles, ovulation occurs later; an ultrasound is recommended for accurate dating.
When should I take a pregnancy test?
Most tests are accurate from the first day of a missed period (about 14 days after ovulation). Some sensitive tests work 4–5 days before.
What are the trimesters?
First trimester: weeks 1–12; Second: weeks 13–27; Third: weeks 28–40. Each brings different developmental milestones.
Is 40 weeks considered full term?
Yes. ACOG defines full term as 39 weeks through 40 weeks + 6 days. Early term is 37–38 weeks, and late term is 41–42 weeks.