Fundal height is the tape measurement from the top of your pubic bone to the top of your uterus, and from the middle of pregnancy it is taken at routine appointments as a quick check on the baby's growth. This fundal height chart by week gives the normal range in centimetres for every week from 16 to 41, from the INTERGROWTH-21st international standard, and the check under it places your own reading on that range.
The guide also covers how the measurement is taken and from which week, why the "centimetres equal weeks" rule drifts near term, what happens if you are measuring small or large, and why nobody can give you a normal range for belly girth.
The short answer: on the INTERGROWTH-21st standard, fundal height in centimetres stays close to the number of weeks until about 32 weeks. The median is 23.8 cm at 24+0, 27.7 cm at 28+0 and 31.4 cm at 32+0, with the 10th–90th centile band about 2 cm either side. Near term the median falls behind, reaching 38.0 cm at 40+0.
Fundal height chart by week, in cm
The chart below is the INTERGROWTH-21st international standard for symphysis-fundal height, published in the BMJ in 2016. It was built from 20,566 measurements in 4,239 healthy, well-nourished women in eight countries, taken with a non-elastic tape whose numbers were turned away from the examiner, so it shows how the uterus grows when pregnancy goes well rather than an average of whatever happened in one place. Each row is an exact stage as your notes write it: 28+0 means 28 weeks and 0 days. The 50th centile (P50) is the median. The 10th and 90th centiles enclose 8 in 10 healthy pregnancies and are the usual screening cut-offs; the 3rd and 97th mark the outer edges. INTERGROWTH-21st recommends the chart from 16 to 40 weeks and marks its 41-week row as extrapolated. Your own maternity unit may plot you on a different chart, so ask which one it uses before comparing numbers.
| Weeks | P3, cm | P10, cm | P50, cm | P90, cm | P97, cm |
|---|---|---|---|---|---|
| 16+0 | 13.2 | 14.0 | 15.8 | 17.6 | 18.5 |
| 17+0 | 14.1 | 14.9 | 16.8 | 18.6 | 19.5 |
| 18+0 | 15.0 | 15.9 | 17.8 | 19.6 | 20.5 |
| 19+0 | 16.0 | 16.9 | 18.8 | 20.7 | 21.5 |
| 20+0 | 16.9 | 17.8 | 19.8 | 21.7 | 22.6 |
| 21+0 | 17.9 | 18.8 | 20.8 | 22.7 | 23.6 |
| 22+0 | 18.8 | 19.8 | 21.8 | 23.8 | 24.7 |
| 23+0 | 19.8 | 20.7 | 22.8 | 24.8 | 25.7 |
| 24+0 | 20.7 | 21.7 | 23.8 | 25.8 | 26.8 |
| 25+0 | 21.7 | 22.7 | 24.7 | 26.8 | 27.8 |
| 26+0 | 22.6 | 23.6 | 25.7 | 27.9 | 28.9 |
| 27+0 | 23.5 | 24.6 | 26.7 | 28.9 | 29.9 |
| 28+0 | 24.5 | 25.5 | 27.7 | 29.9 | 30.9 |
| 29+0 | 25.4 | 26.4 | 28.6 | 30.9 | 31.9 |
| 30+0 | 26.3 | 27.3 | 29.6 | 31.8 | 32.9 |
| 31+0 | 27.1 | 28.2 | 30.5 | 32.8 | 33.9 |
| 32+0 | 28.0 | 29.1 | 31.4 | 33.8 | 34.8 |
| 33+0 | 28.9 | 30.0 | 32.3 | 34.7 | 35.8 |
| 34+0 | 29.7 | 30.8 | 33.2 | 35.6 | 36.7 |
| 35+0 | 30.5 | 31.6 | 34.0 | 36.5 | 37.6 |
| 36+0 | 31.3 | 32.4 | 34.9 | 37.3 | 38.5 |
| 37+0 | 32.0 | 33.2 | 35.7 | 38.2 | 39.3 |
| 38+0 | 32.8 | 33.9 | 36.5 | 39.0 | 40.2 |
| 39+0 | 33.5 | 34.7 | 37.2 | 39.8 | 41.0 |
| 40+0 | 34.1 | 35.4 | 38.0 | 40.5 | 41.8 |
| 41+0* | 34.8 | 36.0 | 38.7 | 41.3 | 42.5 |
Source: INTERGROWTH-21st symphysis-fundal height standard (Papageorghiou et al., BMJ 2016;355:i5662), official centile table © University of Oxford. Stages are exact: 28+0 is 28 weeks and 0 days in your notes. *Values between 40+1 and 41+0 are extrapolated.
Check your fundal height measurement
Enter the stage from your notes and the measurement in centimetres. The check interpolates the centiles to your exact day, so 28+3 is compared with 28 weeks and 3 days rather than rounded to a whole week, and the matching row of the chart is highlighted.
28+0 weeks · 27.7 cm is between the 10th and 90th centiles.
That is within the usual range for this stage of pregnancy.
At 28+0 the median is 27.7 cm, and 8 in 10 healthy pregnancies measure between 25.5 and 29.9 cm.
For information only. Whatever the number, contact your midwife or maternity unit the same day if your baby's movements have slowed or changed.
How to read the answer: between the 10th and 90th centiles is the usual range. Below the 10th or above the 90th is where a measurement usually prompts a second look — a repeat at the next appointment or a growth scan — and the 3rd and 97th centiles show how far out it sits. The check never diagnoses anything: a tape measurement carries an error of a centimetre or more, and the line across several visits says more than any one point.
How is fundal height measured, and from which week?
You lie on your back with an empty bladder. The midwife or doctor finds the top of the pubic bone, the symphysis pubis, and the top of the uterus, the fundus, and runs a non-elastic tape in a straight line between them. In the INTERGROWTH-21st study the tape was held with its numbers facing away until the end, so the examiner could not drift towards the figure they expected, and every measurement was taken twice.
In the UK, NICE recommends offering the measurement at each antenatal appointment after 24+0 weeks, no more often than every two weeks, and plotting it on a growth chart. The recommendation covers singleton pregnancies, and women who are already having regular growth scans are followed with those instead. US sources such as Cleveland Clinic describe measuring from about 20 weeks, when the top of the uterus reaches the navel. Our antenatal appointment schedule shows where the tape fits among the other checks.
Not every country uses a tape. The height of the uterus can also be felt by hand and recorded against landmarks such as the navel, and the WHO's 2016 antenatal care guideline recommends against switching from one method to the other where one is already the usual practice: neither has been shown to improve outcomes over the other.
What can shift a reading
- A full bladder. The standard was measured with the bladder emptied first.
- Who holds the tape. Two examiners can differ by several centimetres on the same bump.
- Your build. A higher body weight or fibroids can add centimetres that are not the baby.
- The baby's position. A baby lying bottom-first, or one whose head has dropped into the pelvis near term, changes the number.
- Amniotic fluid and twins. More or less fluid than average, or a second baby, moves the reading up or down.
Does fundal height in centimetres equal weeks of pregnancy?
Roughly, and only in the middle of pregnancy. The familiar rule of thumb, quoted for example by Cleveland Clinic, is that from about 20 to 36 weeks the measurement in centimetres should be within 2 cm of the number of weeks: 30 to 34 cm at 32 weeks. Set against the INTERGROWTH-21st standard, the rule works well up to about 32 weeks and then drifts. The median grows by a little under a centimetre a week, and the shortfall adds up: 0.6 cm below the week number at 32+0, 2.0 cm below at 40+0.
| Weeks | Rule of thumb, cm | P10–P90, cm | Median, cm |
|---|---|---|---|
| 24+0 | 22–26 | 21.7–25.8 | 23.8 |
| 28+0 | 26–30 | 25.5–29.9 | 27.7 |
| 32+0 | 30–34 | 29.1–33.8 | 31.4 |
| 36+0 | 34–38 | 32.4–37.3 | 34.9 |
| 40+0 | 38–42 | 35.4–40.5 | 38.0 |
By 36+0 the median is 34.9 cm, more than a centimetre under the week number, and by 40+0 it is 38.0 cm. A reading of 36 cm at 40 weeks is "4 cm small" by the rule of thumb but sits inside the standard's 10th–90th centile range of 35.4–40.5 cm, while 41.5 cm at 40 weeks passes the rule yet lies above the 95th centile. Near term, the chart is the better guide.
One more thing changes in the last weeks. Cleveland Clinic notes that fundal height can fall a little after 36 weeks as the baby drops into the pelvis, and that other causes are then checked. Plotting every measurement is meant to catch a flat or falling line across visits, and that line gets the same follow-up as a single low reading.
Measuring small or large for dates: what happens next?
A measurement outside the expected range is a reason to look again, not a verdict. The NICE recommendations are proportionate:
- Small for dates: an ultrasound scan to check the baby's growth and wellbeing is offered, and how soon depends on what else is going on — sooner if you have also noticed reduced movements or your blood pressure is raised.
- Large for dates: a growth scan is considered.
- A line that flattens or climbs steeply across visits matters as much as one low or high reading: the INTERGROWTH-21st authors name a drop or an acceleration across centiles as a reason to refer for a scan.
Most of the time the scan finds an ordinary explanation. For measuring small, Cleveland Clinic lists a small frame or strong abdominal muscles, less amniotic fluid and a baby who has already dropped into the pelvis — alongside fetal growth restriction, which is what the scan is there to rule in or out. For measuring large: a due date that is off, fibroids, a higher body weight, twins, extra amniotic fluid, a baby lying bottom-first or a bigger baby. Our guide to fetal growth percentiles explains what the growth scan measures instead, and ultrasound results explained decodes the report you will be handed.
How accurate is a tape measurement?
Fundal height is a screening measurement, and its error is bigger than the decimal point suggests. In the INTERGROWTH-21st study, with trained staff, a fixed protocol and no time pressure, repeat measurements by the same person fell within a band about 1.5 cm wide; in earlier studies the band between different examiners was around 6 cm. Across observational studies, the tape has picked up anywhere from 17% to 93% of babies who turned out to be small for gestational age.
The trial evidence is thin. A 2015 Cochrane review found a single randomised trial, of 1,639 women, comparing the tape with feeling the abdomen by hand; it showed no difference between the two in detecting poor growth, and the evidence was rated low to very low quality. That is why guidelines ask for every measurement to be plotted: the line across visits carries more information than any single point, and a scan answers the questions a tape cannot.
Is there a normal range for belly girth?
No. The "girth by week" tables that circulate online have no standard behind them. Belly girth is the circumference of your abdomen measured around the navel. It includes your own waist, so your build shapes it as well as the pregnancy, and there is no international standard for it: INTERGROWTH-21st publishes standards for fundal height and for the baby's growth, not for girth, and NICE recommends fundal height, not girth, for tracking growth.
Girth is still worth writing down if you like to watch your bump change, as long as you compare it only with your own earlier numbers. On an ultrasound report, "AC" means something else entirely: the baby's abdominal circumference in millimetres, measured on the scan, which is covered in ultrasound results explained. How the bump itself changes from week to week is in our guide to when you start showing.
When to call your midwife
Call your midwife or maternity unit the same day — do not wait for your next measurement — if:
- your baby's movements have slowed down, stopped or changed pattern;
- you have any vaginal bleeding;
- fluid is leaking from your vagina, as a gush or a trickle;
- you have signs of pre-eclampsia: a severe headache, blurred vision or flashing lights, pain just below the ribs, vomiting, or sudden swelling of your face, hands or feet.
If a growth scan is already booked because you measured small, reduced movements are a reason to call now, not to wait for the scan.
Frequently Asked Questions
What is a normal fundal height at 28 weeks?
At 28+0 weeks the INTERGROWTH-21st median is 27.7 cm, and 8 in 10 healthy pregnancies measure between 25.5 cm (10th centile) and 29.9 cm (90th). The 3rd to 97th centile range is 24.5–30.9 cm. A single reading inside that range says little on its own, and one just outside it usually leads to a repeat measurement or a growth scan rather than a diagnosis.
Should fundal height in cm match the weeks of pregnancy?
Roughly, between about 20 and 36 weeks: the common rule of thumb is the number of weeks plus or minus 2 cm. On the INTERGROWTH-21st standard the median stays within 0.6 cm of the week number up to 32 weeks and then falls behind — 34.9 cm at 36+0 and 38.0 cm at 40+0 — so near term the rule reads perfectly normal measurements as small.
What does it mean if my fundal height is measuring small?
It means the reading sits below the range expected for your stage, usually below the 10th centile on the chart. NICE advises offering an ultrasound scan to check the baby's growth, sooner if you also have reduced movements or raised blood pressure. Common explanations are a small frame or strong abdominal muscles, less amniotic fluid or a baby who has dropped into the pelvis; the scan also checks for growth restriction.
What if my fundal height is measuring large?
NICE advises considering a growth scan when the measurement is large for the stage of pregnancy. The usual explanations are ordinary: a due date that is slightly out, fibroids, a higher body weight, twins, extra amniotic fluid, a baby lying bottom-first, or a bigger baby. The scan measures the baby directly, which the tape cannot do.
When do they start measuring fundal height?
In the UK, NICE recommends offering the measurement at each antenatal appointment after 24+0 weeks, no more often than every two weeks, in a singleton pregnancy, unless you are already having regular growth scans. US sources describe measuring from about 20 weeks. The INTERGROWTH-21st chart itself starts at 16 weeks.
How accurate is a fundal height measurement?
Less accurate than one decimal place suggests. In the INTERGROWTH-21st study, repeat measurements by the same trained person fell within a band about 1.5 cm wide, and in earlier studies the band between different examiners was around 6 cm. A 2015 Cochrane review found too little evidence to say whether the tape beats feeling the abdomen by hand, so it works as a first screen, and the trend across visits counts for more than any one number.
Is belly girth the same as fundal height?
No. Belly girth is the circumference of your abdomen measured around the navel, and because it includes your own waist it reflects your build as well as the pregnancy. No international standard exists for it. Fundal height runs from the pubic bone to the top of the uterus, and it is the measurement NICE recommends and INTERGROWTH-21st publishes centiles for.
What is the INTERGROWTH-21st fundal height chart?
An international standard published in the BMJ in 2016. It was built from 20,566 measurements in 4,239 healthy, well-nourished women in Brazil, China, India, Italy, Kenya, Oman, the UK and the USA, taken with the tape's numbers turned away so the examiner could not steer the reading. It describes growth when pregnancy goes well, and INTERGROWTH-21st recommends it from 16 to 40 weeks.
Fundal height by week — at a glance
Fundal height is the tape measurement from the top of the pubic bone to the top of the uterus. On the INTERGROWTH-21st international standard its median is 23.8 cm at 24+0, 27.7 cm at 28+0, 31.4 cm at 32+0, 34.9 cm at 36+0 and 38.0 cm at 40+0, and the 10th–90th centile band runs about 2 cm either side. NICE recommends measuring it at antenatal appointments after 24 weeks and plotting it on a chart. The "weeks plus or minus 2 cm" rule holds until about 32 weeks, then reads normal term measurements as small. A reading below the 10th or above the 90th centile leads to a repeat or a growth scan, not a diagnosis, and a single measurement can be off by a centimetre or more. Belly girth has no international standard at all.
Inside Baby Novum: the app does not record fundal height — that number belongs in your maternity notes. What it tracks is the measurement you can take yourself: log your belly girth each week in the belly size tracker, and Premium draws it as a growth chart, so you are comparing yourself with yourself. The belly photo timeline adds a weekly bump-photo reminder; the free tier keeps two photos, and Premium adds unlimited photos, a side-by-side view of any two weeks and a slideshow.
Read next
Sources
- Papageorghiou et al., BMJ 2016;355:i5662 — International standards for symphysis-fundal height (INTERGROWTH-21st)
- INTERGROWTH-21st — Symphysis-fundal height standards: centile tables, University of Oxford
- NICE NG201 — Antenatal care, recommendations 1.2.30–1.2.32: monitoring fetal growth
- WHO 2016 — Recommendations on antenatal care for a positive pregnancy experience (recommendation B.2.2)
- Cochrane review 2015 — Symphysial fundal height measurement in pregnancy for detecting abnormal fetal growth
- Cleveland Clinic — Fundal height
Baby Novum is an informational and tracking tool, not a medical device, and does not provide medical diagnosis or treatment. Always consult your doctor or midwife about your pregnancy.