What is a Pregnancy Due Date Calculator?

A pregnancy due date calculator estimates the likely day your baby will arrive. Most calculators, including this one, are based on Naegele’s rule, which adds 280 days (40 weeks) to the first day of your last menstrual period (LMP). Our tool also lets you adjust for cycle length and luteal phase, giving you a more personalized prediction. While every pregnancy is unique, an accurate estimate helps you plan appointments, nutrition, travel, and maternity leave with confidence.

How the Calculator Works (Plain English)

1. Enter your LMP (the first day your last period started).

2. Set your average cycle length (28 is common; many people vary from 24–35 days).

3. Adjust luteal phase (time between ovulation and the next period; typically ~14 days).

4. Tap Calculate to see your Estimated Due Date (EDD), gestational age today, current trimester, conception window, and important milestones.

Why cycle length matters: If your cycle is longer than 28 days, you likely ovulate later, which can shift your due date. Our calculator gently adjusts the estimate to reflect that.

Key Results You’ll See

• Estimated Due Date (EDD): Your likely delivery date based on LMP + adjustments.

• Gestational Age Today: How far along the pregnancy is, in weeks and days.

• Current Trimester: First (0–12 weeks), Second (13–27 weeks), or Third (28–40 weeks).

• Conception Window: The most likely 2–3 day window around ovulation when fertilization may have occurred.

• Milestones:

  • End of first trimester (~13 weeks)

  • Mid-pregnancy scan (~20 weeks)

  • Full term (37–40 weeks)

Why Due Dates Are Estimates (Not Deadlines)

Only about 5% of babies are born on their exact due date. Most arrive between 37 and 42 weeks. Your healthcare provider might refine your due date using early ultrasound, which can be more accurate than LMP if cycles are irregular or the LMP date is uncertain. Think of your due date as a planning anchor—useful, but flexible.

Who Can Use This Calculator?

• Trying to conceive: Estimate your next fertile window or projected due date if conception occurs.

• Newly pregnant: Get an initial EDD before your first appointment.

• Planning travel or work: Align important life events with trimesters and milestones.

• Birth partners & families: Understand timelines to support planning and preparation.

Helpful Tips for More Accurate Results

• Use the earliest ultrasound to confirm dating if your cycles are irregular.

• Track period start dates for a few months to learn your average cycle length.

• Remember that stress, illness, travel, and other factors can affect ovulation timing.

• Always consult your healthcare provider for medical decisions.

First Trimester (Weeks 1–12): What to Expect

• Symptoms: Fatigue, nausea, tender breasts, mild cramping, mood changes.

• Care tips: Prenatal vitamins with folic acid, gentle hydration, small frequent meals.

• Appointments: Blood tests, prenatal screening discussions, dating scan if advised.

• Lifestyle: Avoid smoking/alcohol, review medications with your doctor, prioritize rest.

Second Trimester (Weeks 13–27): The “Easier” Middle

• Symptoms: Energy usually improves, baby movements may begin (~18–22 weeks).

• Care tips: Balanced nutrition with iron and protein, light activity if approved.

• Appointments: Anatomy scan (~20 weeks), glucose screening later in trimester.

• Planning: Consider childbirth classes, hospital registration, and maternity clothing.

Third Trimester (Weeks 28–40+): The Home Stretch

• Symptoms: Backache, swelling, frequent urination, Braxton Hicks contractions.

• Care tips: Sleep on your side, use pillows for support, keep exercising gently if cleared.

• Appointments: More frequent check-ins, group B strep test, birth plan discussions.

• Preparation: Pack your hospital bag, finalize childcare/pet care, prepare the car seat.

When to Contact a Healthcare Provider

Seek medical advice if you have severe pain, heavy bleeding, or if your cycles are very irregular. If you’re pregnant, your provider may confirm dating using an early ultrasound, which can be more accurate than LMP for some people.

Frequently Asked Questions (SEO-optimized)

Q1. How do I calculate my due date from LMP?
Add 280 days (40 weeks) to the first day of your last menstrual period. Our calculator does this automatically and adjusts for your cycle.

Q2. Can I use this if my cycle isn’t 28 days?
Yes. Set your average cycle length (e.g., 32 days) and our tool adapts your estimate.

Q3. Is an ultrasound more accurate than LMP?
Often yes—especially early ultrasounds done in the first trimester. Follow your provider’s advice if your ultrasound-based due date differs.

Q4. What if I don’t know my LMP?
You can estimate based on your conception date or first ultrasound. The tool’s conception window may help, but consult your doctor for precise dating.

Q5. What does “full term” mean?
Pregnancies are usually considered full term at 37–40 weeks. Many babies arrive within this range.

Q6. Is this calculator medical advice?
No. It’s for education and planning. Always work with your healthcare provider for medical guidance.

Q7. How many days after ovulation can I get a positive pregnancy test?
Many tests turn positive around the time of a missed period, but it varies. For best accuracy, test after your expected period date.

Q8. Can stress delay ovulation?
Yes. Stress, illness, travel, and sleep changes can affect cycle timing and may delay ovulation.

Q9. What is a normal luteal phase length?
Often around 12–14 days, but it can vary. If you suspect a luteal phase issue, consult a healthcare provider.

How to Use This Calculator on Our Site (Quick Steps)

1. Open the Pregnancy Due Date Calculator page.

2. Enter your LMP date, cycle length, and luteal phase.

3. Tap Calculate to see your EDD, gestational age, trimester, milestones, and conception window.

4. Use Copy or WhatsApp Share to keep the results handy or share with your partner.