Enter your fundal height measurement in centimeters to estimate its percentile at your gestational age, or estimate a pregnancy-age range from the measurement.
* The chart describes healthy singleton pregnancies. Fundal height and its age estimate do not replace ultrasound or your clinician’s assessment. A reference-chart range is not a dating confidence interval.
How to use this calculator
- Select a mode: “Percentile at GA” or “SFH → GA”.
- Enter the fundal height (SFH) in centimeters.
- For percentile mode, add the gestational age (weeks+days). For SFH → GA mode, GA is estimated for you.
- Read the outputs: SFH percentile with the expected SFH and SD, or an estimated GA with a reference-chart range.
Educational only. SFH can be affected by fetal position, bladder fill, fibroids, BMI, and twins. Ultrasound dating and growth scans guide care if there are concerns.
Last updated: September 11, 2026
Methodology & sources
How the estimate works
- Reference pattern: the percentile compares your measurement with the INTERGROWTH-21st median and spread for the entered gestational age, using the published Papageorghiou equations.
- Edges of the window: the published chart covers 16–42 weeks. Entries from 12 weeks through 15 weeks 6 days, or after 42 weeks, use the same equation as a clearly labelled extrapolation.
- Population spread: the published standard deviation changes with gestational age. It describes spread among study measurements, not uncertainty about your baby’s health.
- Percentile math: for “SFH percentile at GA,” the measurement is compared with the reference median and standard deviation using a normal distribution. Very low or high rounded values are shown as below the 1st or above the 99th percentile.
- GA from SFH: for “estimate GA from SFH,” the separate published dating equation applies to SFH 12–38 cm. Beyond that range, the displayed age is explicitly a reference endpoint, not a date estimate for the entered measurement.
Assumptions and caveats
- Singleton focus: the estimates assume a singleton pregnancy. Multiple gestations, obesity, uterine fibroids, fetal lie, and examiner technique can shift SFH independently of fetal growth.
- Screening tool: SFH is a screening measure. Concerning values or trends typically lead to ultrasound for fetal size, amniotic fluid, and dopplers as indicated.
- Rounding: outputs are rounded for readability. Small day-to-day differences are common and often reflect technique or fetal position.
What the tool shows
- Percentile mode: GA at measurement, entered SFH, approximate percentile, and expected SFH with its spread (SD) at that GA.
- SFH → GA mode: estimated GA (weeks + days), plus the ages where your measurement lies between the chart’s 10th and 90th SFH percentiles. That comparison range is not an 80% probability or confidence interval for your pregnancy age.
Limitations
- Uses the published INTERGROWTH-21st equations; clinic-specific charts may differ.
- Does not incorporate maternal characteristics, parity, or ethnicity-specific customized charts.
- This estimate is intended for routine measurements. Conditions that alter uterine size or palpation, such as fibroids or fluid-volume differences, need clinician interpretation.
- INTERGROWTH-21st fundal-height chart gives the reference percentiles from 16 to 42 weeks.
- NICE antenatal care guidance explains fundal-height screening and when growth concerns need ultrasound.
- Papageorghiou et al., BMJ (2016): international symphysis-fundal height standards provides the median, spread and separate dating equation used here.
Frequently asked questions
What does fundal height (SFH) measure?
SFH is the distance from the pubic symphysis to the top of the uterus. In mid-pregnancy, SFH in centimeters often approximates weeks of gestation.
How accurate is SFH for dating?
SFH is a screening tool. It’s less precise than ultrasound for dating. Use Ultrasound Due Date for the best GA estimate when available.
Why might my SFH percentile be high or low?
Normal reasons include fetal position, bladder fill, body habitus, and measurement variation. Persistent low or high percentiles may prompt an ultrasound. If your dates are uncertain, compare with the Pregnancy Due Date Calculator.
Does this work for twins?
SFH is less reliable with multiples. For planning in twins, use the Twin & Triplet Due Date Calculator and follow your clinician’s scan schedule.
What units does the tool use?
Centimeters. If your measurement is in inches, convert to cm before entering (1 inch = 2.54 cm).
When should I contact my clinician?
Seek care for decreased fetal movement, painful contractions, fluid leakage, or if SFH is consistently very different from expected. Ultrasound guides next steps when needed.