Compare a measured symphysis-fundal height with the expected height for gestational age.
Result
How to use this tool
Weeks of pregnancy, between 20 and 42, when the rule applies.
Symphysis to fundus in cm, measured with an empty bladder.
Measured minus expected, with a within-range, borderline or review flag.
A difference beyond 2-3 cm usually leads to growth assessment, not immediate worry.
Formula & worked example
At 28 weeks with a measured height of 28 cm, the difference is 28 – 28 = 0 cm, within the expected range.
Limitations — read this before you rely on it
Educational use only. This tool is for education only and is not medical advice. Talk to a clinician about any result that worries you, and never change treatment because of a calculator result.
Frequently asked questions
The distance from the pubic bone (symphysis) to the top of the womb (fundus), measured in centimetres at antenatal visits to track fetal growth.
Roughly 28 cm, within about 2 cm, after 20 weeks of pregnancy.
It can reflect measurement variation, fetal position or genuinely slower growth. The usual next step is an ultrasound growth assessment.
It can reflect a full bladder, fetal position, extra fluid, a large baby or twins; again, ultrasound clarifies.
Not reliably, which is why this tool is limited to 20-42 weeks.