Free Pregnancy Due Date Calculator:
Track gestation & baby milestones.
Calculate your estimated due date (EDD), current gestational week, trimester progress, and fetal milestones.
Select the start date of your most recent menstrual cycle.
Days from the first day of one period to the day before the next (21–40 days).
Standard clinical calculation counts 40 weeks (280 days) from the first day of your LMP.
Clinical Trimester Progression & Developmental Milestones
40-week gestational roadmap, fetal growth milestones, and essential maternal checkpoints.
| Classification | BMI Range (kg/m²) | Health Risk Level | Status Marker |
|---|---|---|---|
| Severe Thinness | < 16.0 | High nutritional deficiency risk | Severe |
| Moderate Thinness | 16.0 – 16.9 | Moderate deficiency risk | Underweight |
| Mild Thinness | 17.0 – 18.4 | Mild risk | Underweight |
| Normal Weight | 18.5 – 24.9 | Lowest mortality & disease risk | Optimal |
| Overweight (Pre-obese) | 25.0 – 29.9 | Increased cardiovascular risk | Overweight |
| Obesity Class I | 30.0 – 34.9 | Moderate cardiovascular / metabolic risk | Class I |
| Obesity Class II | 35.0 – 39.9 | Severe cardiovascular risk | Class II |
| Obesity Class III | ≥ 40.0 | Very severe morbidity risk | Class III |
| Dietary Strategy | Daily Caloric Target | Protein Intake | Carbs / Fats Split | Expected Pace |
|---|---|---|---|---|
| Aggressive Fat Loss | -500 to -750 kcal/day (TDEE) | 1.8 – 2.4 g/kg bodyweight | 35% Carbs / 25% Fats | ~1.0 – 1.5 lbs/wk |
| Moderate Cut (Recomp) | -250 to -400 kcal/day (TDEE) | 1.6 – 2.2 g/kg bodyweight | 40% Carbs / 30% Fats | ~0.5 – 0.8 lbs/wk |
| Weight Maintenance | 100% TDEE (Zero Deficit) | 1.4 – 1.8 g/kg bodyweight | 45% Carbs / 30% Fats | Stable Weight (0 lbs) |
| Lean Muscle Hypertrophy | +250 to +400 kcal/day (Surplus) | 1.6 – 2.0 g/kg bodyweight | 50% Carbs / 25% Fats | ~0.25 – 0.5 lbs/wk |
| Menstrual Cycle Phase | Cycle Day (28-day) | Dominant Hormones | Cervical Mucus & Biomarkers | Conception Probability |
|---|---|---|---|---|
| Menstrual Phase | Days 1 – 5 | Estrogen & Progesterone Low | Endometrial lining shed, dry/minimal mucus | Very Low (~0%) |
| Early Follicular Phase | Days 6 – 9 | FSH & Rising Estrogen | Thick, sticky or creamy mucus | Low (~5 – 10%) |
| Fertile Window (High) | Days 10 – 13 | Peak Estrogen & LH Surge | Clear, stretchy, slippery egg-white mucus (EWCM) | High (~25 – 35%) |
| Peak Ovulation Day | Day 14 (± 2 days) | LH Peak & Ovum Release | Follicle ruptures (viable for 12–24 hours) | Maximum (~30 – 38%) |
| Luteal Phase | Days 15 – 28 | High Progesterone (Corpus Luteum) | BBT temp shift (+0.5°F), mucus dries up | Zero (~0%) |
| Trimester Stage | Gestational Weeks | Fetal Developmental Milestones | Maternal Checkpoints & Calorie Delta | Clinical Scans / Tests |
|---|---|---|---|---|
| 1st Trimester | Weeks 1 – 12 | Neural tube closure, heart begins beating (~6 wks), limb buds form | Organogenesis stage (+0 kcal/day), 1–4 lbs total gain | Dating Ultrasound (8-12 wks) |
| 2nd Trimester | Weeks 13 – 27 | Fingerprints, audible heartbeat, initial movements/quickening (~18-20 wks) | Rapid growth (+300 kcal/day), ~1 lb/wk weight gain | Anatomy Scan (18-22 wks) |
| 3rd Trimester | Weeks 28 – 36 | Brain myelination, surfactant in lungs, eyes open, rapid fat storage | Peak energetic demand (+450 kcal/day), ~1 lb/wk | GBS & Growth (35-37 wks) |
| Full Term | Weeks 37 – 40+ | Complete respiratory and metabolic readiness for delivery | Engaged fetal position, spontaneous labor window | Delivery Readiness |
Pregnancy Due Date FAQs
Everything you need to know about gestational age calculation, ultrasound dating, and trimester milestones.
Body Mass Index (BMI) is an epidemiological screening index of weight-for-height. It is calculated by dividing body weight in kilograms by the square of height in meters: BMI = kg / m². For imperial units: (lbs × 703) / inches².
BMI cannot differentiate between dense skeletal muscle and adipose fat tissue. Muscular athletes often register as "overweight". Furthermore, it does not assess fat distribution (such as visceral belly fat). Pair your BMI with waist-to-height ratio and body fat % for complete assessment.
According to the World Health Organization (WHO), a BMI between 18.5 and 24.9 kg/m² represents the optimal healthy range associated with lowest cardiovascular and metabolic mortality risk.
The Deurenberg equation computes: BF% = (1.20 × BMI) + (0.23 × Age) - (10.8 × Sex) - 5.4 (where Sex = 1 for males, 0 for females), validated across clinical DEXA correlation studies.
BMR (Basal Metabolic Rate) is the baseline energy burned at complete rest to support vital organs. TDEE (Total Daily Energy Expenditure) includes BMR plus all physical training, steps, and the thermic effect of digestion. Eating below your TDEE creates a fat loss deficit.
A moderate deficit of 300 to 500 kcal/day (15–20% below TDEE) is ideal. It produces ~0.5 to 1.0 lb of sustainable fat loss per week without causing muscle wasting or metabolic adaptation.
For fat loss and muscle preservation, target 1.6 to 2.2 grams of protein per kg of body weight (0.75–1.0 g/lb). For muscle hypertrophy, 1.6 to 2.0 g/kg in a slight 250–300 kcal surplus optimizes hypertrophy.
Peer-reviewed clinical validation published by the Academy of Nutrition and Dietetics demonstrated that the Mifflin-St Jeor equation predicts resting metabolic rate within 10% of measured calorimetry across 82% of non-obese and obese adults.
Ovulation typically occurs approximately 14 days before your next menstrual period begins. Because sperm can survive in fertile cervical mucus for up to 5 days, your fertile window spans the 5 days prior to ovulation plus the day of ovulation itself (a 6-day window).
A released ovum remains viable for fertilization for only 12 to 24 hours. Timing intercourse in the 2–3 days prior to ovulation ensures viable sperm are already waiting in the fallopian tube when the egg is released.
Implantation typically takes place 6 to 10 days after ovulation. High-sensitivity hCG pregnancy tests can detect early pregnancy around 11 to 14 days post-ovulation (or on the first day of a missed period).
Key biological markers include clear, stretchy, egg-white cervical mucus (EWCM), a positive luteinizing hormone (LH) surge on ovulation strips, mild pelvic aching (mittelschmerz), and heightened libido.
Naegele's rule calculates the Estimated Due Date (EDD) by adding 1 year, subtracting 3 months, and adding 7 days to the first day of your Last Menstrual Period (LMP), based on a standard 280-day (40-week) human gestation.
If you ovulated earlier or later than day 14 of your cycle, an early first-trimester ultrasound measurement (Crown-Rump Length, CRL) is often considered more precise and may adjust your clinical due date by several days.
1st Trimester: Weeks 1 through 12.
2nd Trimester: Weeks 13 through 27.
3rd Trimester: Weeks 28 through 40+.
Full term is clinically defined between weeks 37 and 42.
The Level 2 anatomy scan is performed between weeks 18 and 22 of pregnancy to evaluate fetal organ development, heart chambers, brain structures, spinal integrity, placenta position, and amniotic fluid volume.
Obstetrical Gestation & Due Date Formulas
Naegele’s clinical rule, gestational age formulas, and trimester milestone checkpoints.
Quetelet BMI Index
BMI = Weight (kg) / [Height (m)]²
WHO global standard for identifying nutritional status and morbidity risks across adult populations.
Deurenberg Body Fat Formula
BF% = 1.20×BMI + 0.23×Age - 10.8×Sex - 5.4
Sex = 1 for males, 0 for females. Clinical estimation derived from hydrodensitometry comparisons.
Devine Ideal Weight Equation
Men: 50.0kg + 2.3kg/in > 5ft
Women: 45.5kg + 2.3kg/in > 5ft
Clinical pharmacology standard used to estimate optimal lean body mass target ranges.
Mifflin-St Jeor BMR Equation
Men: 10×W + 6.25×H - 5×A + 5
Women: 10×W + 6.25×H - 5×A - 161
Calculates basal resting energy expenditure with highest accuracy across modern clinical trials.
TDEE Activity Multiplier
TDEE = BMR × Activity Factor (1.2 to 1.9)
Multiplies basal burn by physical movement, exercise thermogenesis (EAT), and NEAT.
Macronutrient Energy Density
Protein: 4 kcal/g | Carbs: 4 kcal/g | Fat: 9 kcal/g
Standard Atwater general factor system for calculating total daily macro gram allocations.
Ogino-Knaus Ovulation Day
Ovulation = LMP + (Cycle Length - Luteal Days)
Calculates exact day of follicular rupture based on an individual's verified luteal phase length.
6-Day Fertile Window Model
Fertile Window = [Ovulation - 5] to [Ovulation + 1]
Accounts for 5-day human sperm longevity in fertile mucus and 12-24 hour egg viability window.
Post-Ovulation Pregnancy Test Day
Earliest Test Date = Ovulation + 11 to 14 Days
Corresponds to peak maternal serum beta-hCG doubling following blastocyst implantation.
Naegele's Pregnancy Rule
EDD = LMP + 1 Year - 3 Months + 7 Days + (Cycle - 28)
Classic obstetrical equation adjusted for menstrual cycle variances to compute 280-day due dates.
Gestational Age Equation
Gestational Age = (Today - LMP Date) / 7 Days
Standard clinical method expressing fetal gestational age in elapsed completed weeks and days.
Fetal Viability Checkpoint
Viability Date = LMP Date + (24 Weeks × 7 Days)
Clinical benchmark at 24 weeks gestation indicating neonatal intensive care viability.
Your Measurement History
Track and monitor your personal records over time (stored privately on your browser).
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