Fundal Height Calculator

Written by Great Medico

Updated September 24, 2026 •2 min read

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Pregnancy and fertility questions are full of dates, ranges, and probabilities—not certainties. Fundal Height Calculator narrows the question to the exact inputs shown and gives a practical estimate without pretending biology runs on a perfect calendar.

What this calculator does

Fundal Height Calculator uses Calculation type, Gestational age — weeks, Additional days, and Measured symphysis-fundal height to calculate fundal height. It is built around the exact fields displayed in this plugin rather than a generic version of the topic. Where supported, it also shows Gestational age and Expected SFH so the primary result is easier to place in context. Pregnancy and fertility dates, hormone trends, and risk scores are estimates built around biologic averages. Cycle variation, ultrasound findings, assisted-reproduction details, and the individual pregnancy can matter more than a single calculated number.

How to use it

Enter or select Calculation type, Gestational age — weeks, Additional days, and Measured symphysis-fundal height. Use the units offered by the calculator and choose the option that matches the actual clinical or timing situation. Check date entries and laboratory units before relying on the output. For paired dates or serial measurements, keep them within the same menstrual cycle, pregnancy, or treatment episode as the calculator requires.

How the calculation works

Gestational age is converted to decimal weeks from the entered weeks and days. The tool assumes expected fundal height in centimeters is numerically equal to gestational age in weeks. In assessment mode it subtracts that expected value from the measured fundal height and reports the difference.

Example

Using the sample values prefilled in this calculator, the primary result is 28 cm (Expected fundal height), Gestational age is 28 weeks, and Expected SFH is 28 cm. This worked example shows how the plugin’s own default inputs flow through the implemented method; replace them with the correct patient, laboratory, imaging, or personal values before interpreting a result.

How to interpret the result

Treat the output as expected fundal height based on the assumptions encoded in this calculator. It can help with planning or understanding a measurement, but pregnancy and reproductive biology vary enough that the calculated date, ratio, or probability should be seen as a range or estimate rather than a guarantee.

Limitations and notes

The “centimeters roughly equal weeks” relationship is a screening rule mainly used in the mid-to-late second and third trimesters, not a precise fetal-size measurement. Maternal body habitus, fibroids, bladder fullness, fetal position, amniotic fluid, multiple pregnancy, and growth disorders can change the measurement.