Pregnancy Calculator — Free Due Date & Week Tracker
Calculate your pregnancy due date and follow week-by-week fetal development through each trimester. Essential timing info for expecting parents.
Standard cycle is 28 days.
April 22nd, 2027
0 weeks, 0 days
Key Milestones
About this calculator
Comprehensive Guide to Pregnancy Tracking and Development
Pregnancy tracking involves monitoring your progress through 40 weeks of gestation, from conception through delivery. Knowing what's happening at each stage helps you:
- Understand fetal development
- Know what to expect physically and emotionally
- Schedule appropriate medical care
- Recognize normal vs concerning symptoms
- Prepare for labor and delivery
- Bond with your baby
A typical pregnancy is divided into three trimesters, each with distinct developmental milestones and maternal changes.
How to Use the Pregnancy Calculator
Our pregnancy calculator tracks your entire pregnancy journey:
Enter Your Last Menstrual Period (LMP)
- First day of your last period
- Foundation for all pregnancy dating
View Your Pregnancy Timeline
- Current week and trimester
- Due date and days remaining
- All past and upcoming milestones
- Fetal development at your stage
- Recommended tests and care
Track Progress
- Week-by-week updates
- Size and weight comparisons
- Major development milestones
- What to expect physically
Formula
Estimated Due Date = Last Menstrual Period + 280 days (40 weeks)
Gestational Age = (Today's Date - LMP) / 7 days
Trimester:
- 1st: Weeks 1-12
- 2nd: Weeks 13-26
- 3rd: Weeks 27-40
The Three Trimesters of Pregnancy
First Trimester (Weeks 0-13)
Duration: 13 weeks + 5 days
Week-by-Week Development Highlights
| Week | Fetal Size | Major Events |
|---|---|---|
| 1-4 | Microscopic | Fertilization, implantation, cell division |
| 5 | Sesame seed (2-3mm) | Heartbeat detectable, neural tube forms |
| 6 | Lentil (4-5mm) | Brain development begins, limb buds appear |
| 7 | Blueberry (7-10mm) | Eye development, intestines form |
| 8 | Raspberry (14-20mm) | "Fetal period" begins, fingers/toes emerge |
| 9 | Grape (23mm) | Gender organs developing (not yet visible) |
| 10 | Prune (31mm) | Teeth developing, elbows/knees forming |
| 11 | Fig (40mm) | Can suck thumb, urinating, hair forming |
| 12 | Plum (54mm) | Fingernails/toenails forming |
| 13 | Peach (75mm, 0.6 oz) | End of first trimester, all major organs present |
Maternal Changes & Experiences
Physical:
- Breast enlargement and tenderness
- Fatigue (extreme in weeks 6-12)
- Nausea and vomiting (morning sickness)
- Frequent urination
- Food cravings or aversions
- Constipation
- Dizziness
- Headaches
Emotional:
- Mood swings (hormonal)
- Anxiety about miscarriage (especially if history)
- Excitement and anticipation
- Ambivalence (normal, even when wanted)
Medical milestones:
- Week 5: First prenatal visit
- Week 8-11: Nuchal translucency ultrasound
- Week 9-13: First trimester screening blood test
- Week 11-12: Option for chorionic villus sampling (CVS) if needed
- Week 13: Miscarriage risk drops significantly
Important Considerations
Miscarriage risk: ~20% of pregnancies (most ~75% occur before 12 weeks)
- Most early miscarriages due to chromosomal problems
- Not preventable or caused by activities (unless injury/infection)
- After 13 weeks, risk drops to ~1-2%
Medication concerns: Discuss all medications/supplements with provider; some are unsafe in pregnancy
Second Trimester (Weeks 14-27)
Duration: 14 weeks
Week-by-Week Development Highlights
| Week | Fetal Size | Major Events |
|---|---|---|
| 14 | Lemon (87mm) | Ears move to proper position, eyebrows appear |
| 16 | Avocado (116mm) | Gender identifiable on ultrasound |
| 18 | Sweet potato (140mm) | Can hear sounds, fingerprints forming |
| 20 | Banana (160mm, 10.5 oz) | Viability begins, major anatomy forms |
| 24 | Corn (292mm, 1.3 lbs) | Viability improved, lungs developing |
| 27 | Cauliflower (366mm, 1.9 lbs) | Eyes opening, hearing fully developed |
Maternal Changes & Experiences
Physical:
- "Baby bump" becomes obvious
- Nausea usually subsides
- Energy returns
- Back pain develops (center of gravity shifting)
- Round ligament pain (sides of abdomen)
- Skin changes (darkening, linea nigra, melasma)
- Hair growth (some areas, shedding others)
Emotional:
- Often best trimester emotionally
- Increased bonding with pregnancy
- Excitement about gender reveal
- Planning and nesting instincts
Medical milestones:
- Week 15-20: Maternal serum screening (quad screen) option
- Week 18-22: Detailed anatomy ultrasound (most thorough)
- Week 20: Halfway through pregnancy!
- Week 24-28: Gestational diabetes screening test
- Week 24: Major viability milestone
Important Considerations
Viability: Baby could survive with intensive medical care at 22-24 weeks, but outcomes much better at 28+ weeks
Quickening: Mother feels baby movements, which accelerates bonding and reassurance
Third Trimester (Weeks 28-40+)
Duration: 12 weeks (plus potential overdue time)
Week-by-Week Development Highlights
| Week | Fetal Size | Major Events |
|---|---|---|
| 28 | Eggplant (375mm, 2.2 lbs) | Eyes can focus, developing sleep-wake cycles |
| 32 | Squash (430mm, 3.8 lbs) | Most development complete, rapid growth continues |
| 36 | Cantaloupe (480mm, 5.8 lbs) | Typically turns head-down for delivery |
| 37 | Winter melon (485mm, 6.3 lbs) | Full term, can be born any time with good outcomes |
| 40 | Watermelon (510mm, 7-8 lbs) | Due date, ready for delivery |
Maternal Changes & Experiences
Physical:
- Significant weight gain and discomfort
- Shortness of breath (baby pressing on lungs)
- Swelling in feet and ankles
- Sleep difficulties (can't find position)
- Braxton-Hicks contractions (practice contractions)
- Increased urinary frequency
- Vaginal discharge increases
- Pelvic pressure and heaviness
- Exhaustion (physical and emotional)
Emotional:
- Anxious about labor/delivery
- Impatient to meet baby
- Nesting instinct intensifies
- Some mood changes
- Fear about motherhood
Medical milestones:
- Week 28: Anemia screening
- Week 28-36: Rh antibody screening (if Rh negative)
- Week 35-37: Group B Streptococcus (GBS) screening
- Week 36+: Cervical exams if planning vaginal delivery
- Week 37+: Considered "term"—labor expected
- Week 39-40: Optimal time for delivery
- Week 42+: Postterm—increased complications risk
Important Considerations
Non-stress tests: May be done regularly in final weeks to ensure baby well-being
Induction discussion: Between 39-42 weeks, timing of delivery discussed with doctor
Cord blood banking: Decision needed about private vs public banking
Fetal Growth Milestones by Weight
| Weight | Week | What It Means |
|---|---|---|
| < 0.5 oz | Before week 13 | Embryonic period, miscarriage risk higher |
| 1 oz | Week 16 | End of critical organ formation |
| 3.5 oz | Week 20 | Viability begins (rough minimum) |
| 1 lb | Week 28 | Viability much improved |
| 2.5 lbs | Week 32 | Most systems developed, survival likely with NICU |
| 4 lbs | Week 36 | Term—can be born with minimal complications |
| 5-5.5 lbs | Week 37-38 | Ideal weight, all systems developed |
| 7-7.5 lbs | Week 39-40 | Average birth weight, fully developed |
Common Pregnancy Concerns and When to Seek Care
First Trimester Warning Signs
Call your doctor if you experience:
- Heavy vaginal bleeding or clots
- Severe cramping or sharp pain
- Severe nausea/vomiting preventing eating/drinking
- Fainting or severe dizziness
- Signs of infection (fever, chills)
Second & Third Trimester Warning Signs
Call your doctor immediately if you have:
- Vaginal bleeding
- Severe abdominal or pelvic pain
- Persistent severe headaches
- Vision changes
- Severe swelling
- Chest pain
- Severe shortness of breath
- Signs of infection (fever, flu-like symptoms)
- Leaking fluid (possible amniotic fluid)
Signs of Labor (Week 37+)
When to go to hospital/birth center:
- Regular contractions 5-10 minutes apart
- Bloody show (mucus plug)
- Fluid leaking from vagina (broken water)
- Severe back pain with contractions
Trimester-by-Trimester Lifestyle
First Trimester
Exercise: Safe, continue as before (don't start new intense programs) Nutrition: Focus on folate, iron; eat when possible if nauseous Work: Can continue; tell employer when ready Sexual activity: Safe (no restrictions unless complications)
Second Trimester
Exercise: Safest for new activity; walking and swimming ideal Nutrition: Add ~340 calories/day; iron-rich foods important Travel: Safe (avoid after 36 weeks) Sexual activity: Safe; may be more comfortable; may increase libido
Third Trimester
Exercise: Continue but lower impact; pelvic floor exercises helpful Nutrition: Add ~450 calories/day; calcium important for baby Travel: Not recommended after 36 weeks Sexual activity: Safe until water breaks; may relieve discomfort
Preparing for Delivery
By 36 Weeks
- Hospital/birth center tour completed
- Birth plan created
- Pediatrician selected
- Car seat installed
- Hospital bag packed
- Childcare arranged (if other children)
By 37 Weeks
- All prenatal visits more frequent (weekly)
- Fetal monitoring as needed
- Labor signs reviewed
- Pain management options discussed
- Partner/support person prepared
By 39-40 Weeks
- Ready for labor anytime
- Final preparations complete
- Expecting labor within 1-3 weeks
- Monitoring for overdue pregnancy (after 42 weeks)
Step-by-Step Example
Example Pregnancy Week Calculation
Scenario: Last menstrual period (LMP) on April 1, 2026
Calculation:
- Today's date: May 27, 2026
- Days since LMP: April 1 to May 27 = 56 days
- Weeks: 56 ÷ 7 = 8 weeks (8 weeks and 0 days)
- Gestational age: 8 weeks + 0 days
Pregnancy Milestones:
- 8-week stage: Embryonic period ending, fetal period beginning
- Ultrasound dating at this stage: Accurate within ±2 days
- Current size: Approximately 1.6 inches (4 cm) crown to rump
Due Date: April 1, 2026 + 280 days = December 7, 2026
Interpretation: At 8 weeks, major organ systems are forming. This is typically when first ultrasound dating occurs for confirmation and accuracy.
Frequently Asked Questions
Is my due date exact?
No. Due date is an estimate. Only ~5% deliver on exact date. Plan for ±2 week window. After 42 weeks, induction usually recommended.
When will I feel the baby move?
First-time mothers: 16-20 weeks. Subsequent pregnancies: 13-16 weeks. Earlier feeling doesn't mean earlier delivery.
What's normal weight gain?
For normal pre-pregnancy BMI: 25-35 lbs total (about 1 lb/week in 2nd/3rd trimester). More variation for underweight/overweight/obese starting BMIs.
When should I stop working?
Depends on job demands. Many work until 36-38 weeks. Some stop earlier if complications or strenuous job. Discuss with employer and doctor.
Is it normal to be anxious about labor?
Very normal. Talk to healthcare team, take childbirth classes, discuss fears. Most labors end safely.
When does the baby turn head-down?
Usually by 36 weeks. Breech at 36+ weeks may warrant interventions (external cephalic version or planned C-section).
What happens after 42 weeks?
Risk of stillbirth and complications increases. Induction typically recommended. Non-stress tests done if waiting.
Related Calculators
Due Date Calculator • Pregnancy Weight Gain Calculator • Conception Calculator • Ovulation Calculator
Sources & References
- ACOG - Pregnancy Information
- CDC - Pregnancy and Childbirth
- NIH - Pregnancy Research
- WHO - Maternal Health
Disclaimer
This calculator is provided for educational and informational purposes only. It is not medical, fitness, nutritional, or professional advice. Results are estimates based on the assumptions and inputs you provide.
Actual results may differ significantly due to:
- Individual variations in metabolism and physiology
- Changes in activity level, diet, and lifestyle
- Age, genetics, and medical conditions not accounted for
- Equipment calibration and measurement accuracy
- Environmental and seasonal factors
Do not rely on this calculator for:
- Medical diagnosis or treatment decisions
- Personalized fitness or nutrition planning without professional input
- Determining safe exercise intensity or duration
- Managing health conditions
- Making major life or health decisions
Before making any health or fitness decisions, consult with:
- A licensed physician or healthcare provider
- A registered dietitian or nutrition specialist
- A certified fitness trainer or exercise physiologist
- A medical professional if you have health conditions
Past performance and estimates do not guarantee future results. Always verify important information independently and consult qualified professionals for your individual circumstances.
Frequently Asked Questions
What is my due date and how is it calculated?
Your estimated due date (EDD) is typically calculated as 40 weeks (280 days) from the first day of your last menstrual period (LMP). This is known as Naegele's rule. If you know your conception date or have an ultrasound dating, those can provide a more precise estimate.
What inputs does the Pregnancy Calculator need?
The calculator asks for the first day of your last menstrual period and, optionally, your average cycle length. If you prefer to calculate from a known conception date, you can enter that instead. Some versions also accept an ultrasound date for greater accuracy.
What is gestational age and how is it different from fetal age?
Gestational age counts from the first day of your last menstrual period, so at the moment of conception you are already considered about 2 weeks pregnant. Fetal age (also called embryonic age) counts from the moment of fertilization. Doctors and this calculator use gestational age, which is why pregnancy is described as 40 weeks even though conception-to-birth is roughly 38 weeks.
How does the calculator show pregnancy progress by trimester?
Pregnancy is divided into three trimesters: the first (weeks 1–13), second (weeks 14–26), and third (weeks 27–40). Based on your LMP or conception date, the calculator shows which trimester you are in, how many weeks and days along you are, and what major milestones or development stages are happening around that time.
Are due date calculations always accurate?
The due date is an estimate — only a small percentage of babies are born exactly on their EDD. Ultrasound dating in the first trimester is generally the most reliable method. Factors like cycle length variation and late or early ovulation can shift the true due date by several days. Always discuss dating with your healthcare provider.
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