Weight
Record in kgA body-weight reading taken during the same measurement session.
Enter the reading from the scale alongside the physical measurements.
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Method guide
Modified YMCA Body Fat Calculator
Uses body weight and waist circumference, plus wrist, hip and forearm circumferences for women.
Calculate
- Accuracy
- ±4-6%Typical error against a reference method
- Equipment
- a soft tape measure, a body-weight scale
- Measurement count
- 2 for men · 5 for women
Counts include age, weight and height when required.
How to measure
How to take the measurements
Equipment and Good Technique
Use a flexible tape directly against the body where practical. A good circumference reading follows one level path, stays snug without compressing the skin, and is read without twisting the tape. Stand naturally and keep the measured area relaxed rather than changing posture to influence the result.
Put the body-weight scale on a firm, level surface and use the same scale when comparing sessions. Stand still with weight balanced before recording the displayed value.
Required Inputs and Measurement Locations
Measure every item listed for your calculation. Labels show when an input applies only to men or women.
Waist Circumference
Record in cmAround the waist at the method-specific level.
Relax the abdomen, keep the tape level, and reuse the same marked waist level.
Wrist Circumference
Women onlyRecord in cmAround the smallest point of the wrist.
Relax the hand, locate the narrowest circumference, and keep the tape snug without indenting skin.
Hips Circumference
Women onlyRecord in cmAround the widest point of the hips and buttocks.
Stand evenly, circle the fullest point, and check from the side that the tape remains level.
Forearm Circumference
Women onlyRecord in cmAround the widest part of the forearm.
Relax the arm, locate its largest circumference, and read without flexing or compressing the skin.
Measurement Protocol
Follow this sequence
- Measure under repeatable conditions and take the weight and circumferences in the same session.
- Choose the correct gender-specific input set before starting the tape measurements.
- Work through the listed circumferences in order, using the same side for the wrist and forearm whenever you repeat the method.
- Remove and replace the tape for a second reading at every circumference.
- If two readings disagree, find the landmark again and check tape level and tension before repeating.
Accuracy and mistakes
How accurate is the Modified YMCA method?
Modified YMCA has an estimated accuracy range of ±4–6% with proper technique. Use that range alongside the method’s practical limitations when deciding whether it suits your measurements.
Who it suits: People who want a tape-based method, with a short men’s input set and additional circumference inputs for women.
The trade-off: The men’s calculation has a short input set, while the women’s calculation requires three additional circumference landmarks.
What This Method Measures
Uses body weight and waist circumference, plus wrist, hip and forearm circumferences for women.
Modified YMCA begins with body weight and waist circumference for everyone. Women also measure the wrist, hips and forearm. Choose the correct gender first, then collect only the measurements listed for that calculation.
This method suits people who have a scale and soft tape but do not want to use calipers. Its tradeoff is that the women’s calculation needs several different circumference landmarks; careful tape level and tension matter at each one, not only at the waist.
- Required inputs
- 2–5 per calculation, with gender-specific inputs labelled below.
- Equipment
- Prepare a soft tape measure and a body-weight scale.
Common mistakes that change the result
- Assuming the men’s and women’s calculations require the same inputs.
- Measuring the wrist or forearm with the hand and arm tensed.
- Tilting the tape around the hips instead of keeping one level line.
- Changing the chosen waist level between repeat readings.
- Combining a current circumference with a weight from another session.
What the estimate means
The calculator turns the recorded inputs into a body fat percentage estimate. For Modified YMCA, the estimated accuracy range is ±4–6% with proper technique. A range is not a promise that one reading is exact.
Treat the result as an estimate. When tracking changes, compare readings collected with the same method and procedure. A changed tool, landmark, body side, timing or operator can make readings less comparable. The number does not diagnose health or replace qualified advice, and formulas with different inputs are not interchangeable.
How this compares to other methods
Ordered by typical error, lowest first. Counts include age, weight and height when required.
| Method | AccuracyTypical error against a reference method | Measurement count | Equipment |
|---|---|---|---|
| Parrillo | ±3-4% | 10 | skinfold calipers, a body-weight scale |
| Jackson & Pollock 7-Site | ±3-4% | 8 | skinfold calipers |
| Jackson & Pollock 4-Site | ±3.5-4.5% | 5 | skinfold calipers |
| Durnin & Womersley | ±3.5-5% | 5 | skinfold calipers |
| Jackson & Pollock 3-Site | ±4-5% | 4 | skinfold calipers |
| Covert Bailey | ±4-5% | 5 | a soft tape measure |
| U.S. Navy | ±4-6% | 3 for men · 4 for women | a soft tape measure, a reliable way to measure standing height |
| Modified YMCACurrent method | ±4-6% | 2 for men · 5 for women | a soft tape measure, a body-weight scale |
| YMCA | ±5-7% | 2 | a soft tape measure, a body-weight scale |
Where to Go Next
Read the evidence guide
Review the sources and limitations behind Modified YMCA on its paired research page.
View research →Use the calculator app
Take your prepared readings to Body Fat Calculator, select Modified YMCA, and enter the measurements listed for your calculation.
PRO+ includes measurement history and progress tracking in the app. You can also sync app results with Apple Health on iOS when you enable the integration and grant permission.
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