Pregnancy Calculators

Amniotic Fluid Index Calculator

Interpret an Amniotic Fluid Index (AFI) measurement against standard oligohydramnios, normal, and polyhydramnios reference ranges.

Bishop Score Calculator

Calculate the Bishop Score from cervical examination findings to assess readiness for labor induction.

Conception Calculator

Estimate your conception date from a last period date, a due date, or a birth date, with the specific formula behind each of the three methods.

Crown-Rump Length to Gestational Age Calculator

Calculate gestational age from an early ultrasound crown-rump length (CRL) measurement using the standard Robinson formula.

Due Date Calculator

Estimate your due date using Naegele's rule with a cycle-length adjustment, plus your current gestational age and trimester from your last period.

Due Date Calculator

Estimate your due date from a last period date, a conception date, or an IVF embryo transfer date, using the formula matched to each starting point.

Fetal Weight Calculator

Estimate fetal weight from BPD, HC, AC and FL ultrasound measurements using the 4-parameter Hadlock formula, the obstetric ultrasound standard.

Fundal Height to Gestational Age Calculator

Estimate gestational age from fundal height measurement using McDonald's Rule, a standard prenatal screening tool.

hCG Doubling Time Calculator

Calculate hCG doubling time from two blood test results and the hours between them to check against normal early pregnancy patterns.

IOM Pregnancy Weight Gain Recommendation Calculator

Find the recommended total pregnancy weight gain range for a singleton pregnancy based on pre-pregnancy BMI, per Institute of Medicine guidelines.

IVF Due Date Calculator

Estimate your IVF due date from your embryo transfer date and transfer type, with the fertilization date and equivalent LMP date both shown.

Ovulation Calculator

Calculate your estimated ovulation day and five-day fertile window from your last period date, average cycle length, and luteal phase length.

Ovulation Calculator

Estimate ovulation day either forward from your last period and cycle length, or backward from your next expected period and luteal phase length.

Pregnancy Blood Volume Increase Calculator

Estimate the expected increase in blood volume during pregnancy from pre-pregnancy blood volume, based on typical physiologic expansion.

Pregnancy Conception Calculator

Estimate both your likely conception window and your projected due date together from a single last period date and average cycle length.

Pregnancy Trimester Calculator

Determine which trimester of pregnancy corresponds to a given gestational age in weeks.

Pregnancy Week Calculator

Find your current pregnancy week, day, and trimester from either your last menstrual period date or a known clinician-provided due date result.

Pregnancy Weeks to Months Calculator

Convert pregnancy gestational age from weeks to both calendar months and traditional lunar months.

Pregnancy Weight Calculator

Find your pre-pregnancy BMI category and the IOM-recommended total pregnancy weight gain range in pounds and kilograms that applies to it.

Pregnancy Weight Gain Calculator

Track your pregnancy weight gain against an IOM-based target range paced week by week for your pre-pregnancy BMI category and current week.

Forty Weeks, Counted Carefully

Pregnancy dates, weight gain ranges, and fetal development all follow trackable timelines that help both expecting parents and care providers know what to expect and when. These ten calculators cover that timeline and tracking math.

Disclaimer: These calculators are for informational and educational purposes only and do not replace prenatal care from a qualified healthcare provider. Always follow your doctor or midwife's guidance for your specific pregnancy.
How a due date is actually calculated: the standard method (Naegele's Rule) adds 280 days — 40 weeks — to the first day of the last menstrual period, assuming a typical 28-day cycle. It is an estimate, not a prediction of the exact birth day: only about 1 in 20 babies are actually born on their calculated due date, with a full-term range spanning several weeks around it. The Due Date Calculator and Conception Calculator both work from this same standard method, or from IVF transfer dates when applicable via the IVF Due Date Calculator.

Popular Pregnancy Calculators

  • Pregnancy Week Calculator — finds current pregnancy week and trimester from due date or last period.
  • Fetal Weight Calculator — estimates fetal weight from ultrasound measurements.
  • Pregnancy Weight Gain Calculator — tracks weight gain against standard recommended ranges by pre-pregnancy BMI.

Related: Baby & Parenting Calculators for after birth.