Fundal Height Calculator
Measure and interpret fundal height to assess fetal growth. After 20 weeks, fundal height in centimeters roughly equals gestational age in weeks (±2 cm). Discrepancies may indicate growth restriction or macrosomia.
Did our AI summary help? Let us know.
McDonald's rule ±2-3 cm normal Serial > single
Ready to run the numbers?
Why: Fundal height screens for growth problems. Serial measurements track fetal growth trajectory.
How: Compare measured fundal height to expected (gestational age in weeks). ±2-3 cm is normal variation.
Run the calculator when you are ready.
Sample Scenarios
Current Measurement
Pregnancy Details
Maternal Factors
Recommended Actions
For informational purposes only — not medical advice. Consult a healthcare professional before acting on results.
🏥 Health Facts
cm ≈ weeks (20-36). McDonald's rule for fetal growth screening.
— McDonald's rule
±2-3 cm normal range. Serial measurements more reliable than single.
— Clinical guidelines
What is Fundal Height?
Fundal height (SFH) is the distance from the pubic bone to the top of the uterus. After 20 weeks, fundal height in cm roughly equals gestational age in weeks (±2 cm).
How is Fundal Height Measured?
Lie flat with empty bladder. Provider locates the top of the uterus and measures from pubic bone to fundus with a tape measure.
When is it Measured?
Routine prenatal visits from about 20 weeks until delivery. Serial measurements over time are more valuable than single readings.
McDonald's Rule
Fundal Height (cm) ≈ Gestational Age (weeks). Most accurate between 20-36 weeks. After 36 weeks, baby may drop, reducing measurement.
Normal Variation
Acceptable range: Expected ± 2-3 cm. Variation due to maternal body habitus, fetal position, bladder fullness, and measurement technique.
Small for Dates
Measurements 3+ cm below expected may indicate IUGR, oligohydramnios, or incorrect dating. Ultrasound recommended.
Large for Dates
Measurements 3+ cm above expected may indicate LGA baby, polyhydramnios, or multiple pregnancy.
Multiple Pregnancy
Twins: Add approximately 4-6 cm to expected singleton measurement. Multiple pregnancies naturally have larger uterine size.
Interpretation Guide
Within ±2-3 cm: Continue routine care. 3-4 cm deviation: Repeat in 2-3 weeks. 4+ cm deviation: Ultrasound recommended.
When to Seek Help
Discuss with provider if measurements are consistently off, you notice decreased fetal movement, or have concerns about growth.
Related Calculators
Bishop Score Calculator
Assess cervical readiness and predict labor induction success
HealthhCG Levels Calculator
Analyze hCG progression and doubling time in early pregnancy
HealthMCA Calculator
Assess fetal anemia risk through MCA Doppler peak systolic velocity
HealthNuchal Translucency Calculator
Assess chromosomal abnormality risk from NT ultrasound measurement
HealthA-a Gradient Calculator
Calculate the Alveolar-arterial (A-a) oxygen gradient to assess oxygenation efficiency. Helps differentiate between pulmonary and extrapulmonary causes of...
HealthAdvanced ABI Calculator (Ankle-Brachial Index)
Comprehensive Ankle-Brachial Index calculator with multiple measurement methods, advanced PAD risk assessment, exercise testing capability, cardiovascular...
Health