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Fundal Height Calculator

Created by Łucja Zaborowska, MD, PhD candidate
Reviewed by Anna Szczepanek, PhD and Steven Wooding
Based on research by
Papageorghiou AT, Ohuma EO, Gravett MG, Hirst J, da Silveira MF, Lambert A, Carvalho M, Jaffer YA, Altman DG, Noble JA, Bertino E, Purwar M, Pang R, Cheikh Ismail L, Victora C, Bhutta ZA, Kennedy SH, Villar J; International Fetal and Newborn Growth Consortium for the 21st Century (INTERGROWTH-21st). International standards for symphysis-fundal height based on serial measurements from the Fetal Growth Longitudinal Study of the INTERGROWTH-21st Project: prospective cohort study in eight countries; BMJ; 2016
Last updated: Jan 18, 2024


Our fundal height calculator is an excellent tool for a variety of needs:

  • Fundal height estimation based on the age of the pregnancy;
  • Gestational age computed from the fundal height during pregnancy; and
  • Birth weight calculations based on the fundal height by week.

Stay with us and find out how to calculate fundal height and how to measure it; we'll also talk about using our fundal height percentile calculator and how to squeeze the most out of its functions. 🤰

What is fundal height?

Fundal height is a measurement of a pregnant uterus, performed to assess fetal growth and development.

We can measure the fundal height in pregnancy by using simple tailor's tape — we need to find the length between the top of the uterus and the mother's pubic symphysis. 🤰

💡 The pubic symphysis is a joint that connects both of our pubic bones, located just above the genitalia. That's the protruding, bony part you can feel when touching the very bottom of your front torso.

How to calculate fundal height?

Fundal height is usually measured, but we can also calculate it using the age of the pregnancy — the gestational age.

Here's the exact formula that we used in our fundal height calculator:

Median SFH=5.1333+(0.1058×GA2)(0.02312×GA2)×ln(GA)\scriptsize \mathrm{Median}\ SFH \!=\! 5.1333 \!+\! (0.1058 \!\times\! GA^{2}) \!-\! (0.02312 \!\times\! GA^{2}) \!\times\! \ln(GA)

where:

  • Median SFH — short form of Median symphysis-fundal height, given in centimeters (cm);
  • GA — stands for the gestational age in weeks and days, turned into decimals. (e.g., 1 week 1 day = 1 ⅐ weeks = 1.14 weeks); and
  • ln — a short way to write the natural logarithm.

This fundal height estimation was established by the INTERGROWTH-21st project.

How to use the fundal height calculator?

All the things you'd like to know, but you're afraid to ask, step by step!

  1. Choose the type of calculation:

    a) SFH percentile — computes the median fundal height based on your gestational age and compares it to your actual measured fundal height and its percentile.

    b) SFH to gestational age — computes gestational age based on a measured fundal height.

    c) SFH to fetal weight — answers the question of how to calculate baby weight by fundal height.

  2. Input all the necessary data:

    • Measured SFH — the distance between fundal height and the pubic bone, measured with the tailor's tape.
    • GA weeks/days — gestational age in weeks and days.
  3. Enjoy your results 🎉

💡 Our calculators allow you to change the unit of almost every variable, and match it to your needs! In most of the cases the calculations can be also performed both ways!

How to calculate gestational age from fundal height?

There are two different ways to complete this task:

  1. We may use the McDonald's rule for fundal height by week:

    • At 12 weeks, the uterus' fundus is located just above the pubic bone.
    • During the 22nd week of pregnancy, the fundus of the uterus can be palpated at the height of the belly button.
    • At 36 weeks, the fundus reaches its highest point — the bottom part of the sternum.
    • The uterus then begins to move down — the baby prepares for the delivery, its head enters the birth canal.
  2. We may also use the formula:

    GA = 6.5858 - 2.7073 × √SFH + (1.2952 × SFH),

    where:

    • GA — gestational age in weeks;
    • — symbol of a square root; and
    • SFH — symphysis-fundal height given in centimeters (cm).

How to calculate baby weight by fundal height?

Fundal height during pregnancy might be an indicator for the development and wellbeing of the fetus. There are different methods that we can use for assessing the baby's weight — one of them is the fetal weight percentile calculator (the crown-rump length calculations might also be of use) — another helpful and popular method is measuring the fundal height.

Here's Johnson's formula used in our fundal heightbirthweight calculator:

Fetal weight = (SFH - Weight - Vertex) × 155,

💡 This formula can be used only for babies in the vertex position (with their head down). The fetus usually takes this location after the 33-36 weeks of the pregnancy.

where:

  • Fetal weight — given in grams (g).
  • SFH — symphysis-fundal height given in centimeters (cm).
  • Weight:
    • Takes the value of 1, if mother weights >91 kg (200 lb).
    • Takes the value of 0, if mother weight ≤91 kg (200 lb).
  • Vertex — the top of the head of your baby.
    • Takes the value of 12, if vertex is above ischial spine.
    • Takes the value of 11, if vertex is below ischial spine.

Yay, you got it! Would you like to discover something more? 👶 We prepared some great tools that may help you deal with the pregnancy and your child's upbringing!

Fundal height measurement charts

We can use two different types of charts that describe the fundal height in pregnancy; the first one of them can be used by everyone, the second is mostly meant for medical professionals:

  1. The simplest fundal height measurement chart. 🍼

Gestational age

Fundal height estimation

12-14 weeks

Pubic bone (top)

20-22 weeks

Belly button

36-40 weeks

Sternum (bottom)

37-40 weeks

Uterus lowers its position

  1. The complex version used in the fundal height percentile calculator.

    The fundal height chart, 16-42 weeks of the pregnancy — all fundal heights are given in millimeters (mm).

Gestational age (exact weeks)

Centiles

3rd

5th

10th

50th

90th

95th

97th

16

132

135

140

158

176

181

185

17

141

144

149

168

186

191

195

18

150

154

159

178

196

202

205

19

160

163

169

188

207

212

215

20

169

173

178

198

217

222

226

21

179

182

188

208

227

233

236

22

188

192

198

218

238

243

247

23

198

201

207

228

248

254

257

24

207

211

217

238

258

264

268

25

217

221

227

247

268

274

278

26

226

230

236

257

279

285

289

27

235

239

246

267

289

295

299

28

245

249

255

277

299

305

309

29

254

258

264

286

309

315

319

30

263

267

273

296

318

325

329

31

271

276

282

305

328

335

339

32

280

284

291

314

338

344

348

33

289

293

300

323

347

354

358

34

297

301

308

332

356

363

367

35

305

309

316

340

365

372

376

36

313

317

324

349

373

380

385

37

320

325

332

357

382

389

393

38

328

332

339

365

390

397

402

39

335

339

347

372

398

405

410

40

341

346

354

380

405

413

418

41

348

353

360

387

413

420

425

42

354

359

369

393

420

427

432

FAQ

How do I calculate fundal height?

To calculate the median symphysis fundal height (SFH) use the formula:

Median SFH (cm) = 5.1333 + (0.1058 × GA²) - (0.02312 × GA²) × ln(GA),

where GA is the gestational age in weeks.

Can fundal height predict birth weight?

Fundal height can predict the birth weight of your baby — however, this method can only be used after 33-36 weeks of the pregnancy, when your baby is in the vertex position (with their head down).

In order to calculate the estimated birth weight using the fundal height we need to use the Johnson's formula:

Fetal weight = (SFH - Weight - Vertex) × 155

When to start measuring fundal height?

You may start measuring your fundal height during the 12-14th week of the pregnancy — that's when the fundus of the uterus starts to be easily palpable above your pubic bone.

Łucja Zaborowska, MD, PhD candidate
Calculation type:
SFH percentile
GA weeks
#
GA days
#
Measured SFH
in
Expected SFH
6.224
in
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