Protocol - Arm Span

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The individual stands against the wall with his or her arms outstretched at shoulder level. Measurement of the arm span is the maximum distance between the extended middle fingers of the right and left hands, measured across the back.

Specific Instructions

The recommendations from Expert Review Panel follow.

Several overarching, critical issues for high-quality data collection of anthropometric measures that optimize the data in gene-environment etiologic research include (1) the need for training (and retraining) of study staff in anthropometric data collection; (2) duplicate collection of measurements, especially under field conditions; (3) use of more than one person for proper collection of measurements, where required; (4) accurate recording of the protocols and measurement units of data collection; and (5) use of required and properly calibrated equipment.

The notion of recommending replicate measurements comes from the reduction in random errors of measurement and accompanying improved measurement reliability when the mean of multiple measurements is used rather than a single measurement. This improvement in measurement reliability, however, depends on the reliability of a single measurement in the hands of the data collectors in a particular study (Himes, 1989). For example, if a measure such as recumbent length in a given study has a measurement reliability of 0.95 (expressed as an intraclass correlation coefficient), taking a second measurement and using the mean of the two measurements in analyses will improve the reliability to only 0.97, yielding only a 2% reduction in error variance for the additional effort. If, in the same study, the reliability of a single triceps skinfold measurement was 0.85, using the mean, including a replicate measurement, would raise the reliability to 0.92 and yield a 7% reduction in error variance, more than a three-fold improvement compared with recumbent length. The intraclass correlation coefficient is specifically recommended here for assessing reliability because it takes account of random and systematic errors of measurement, whereas the interclass correlation (e.g., Pearson correlation) takes account of only random errors of measurement. Because the benefits of taking replicate measurements are so closely linked with the existing measurement reliability, it is recommended that as a part of the training of those who will be collecting anthropometry data, a reliability study be conducted that will yield measurement reliability estimates for the data collectors, protocols, settings, and participants involved in that particular study (Himes, 1989). If the measurement reliability for a single measurement is greater than or equal to 0.95, the recommendation is that replicate measurements are not necessary and will yield little practical benefit. If the measurement reliability is less than 0.95, the recommendation is to include replicate measurements as prescribed.

If replicate measurements are indicated because of relatively low reliability, a second measurement should be taken, including repositioning the participant. A third measurement should be taken if the first two measurements differ by more than 0.5 cm. If it is necessary to take a third measurement, the two closest measurements are averaged. Should the third measurement fall equally between the first two measurements, all three should be averaged.

Interpretation of Findings

Generally, in children, the arm span measurement is approximately 1 cm shorter than height; in adolescents, the arm span is approximately the same length as height; and in adults, the arm span measurement exceeds height by approximately 5 cm. There are racial/ethnic differences, however, and appropriate references should be consulted for proper interpretation.




This protocol is part of an examination survey. It requires a tape measure at least 2 m long, a flat surface (usually a wall), and an adjustable block that is fixed to the wall. The spool of the tape measure is fixed to the adjustable block. The block serves as the contact point for the middle (longest) finger of the right hand, which is in contact with the block when the participant is positioned. The block must be movable so that it can be adjusted vertically to accommodate individuals of varying stature. The block is adjusted to bring the tape to the shoulder level for the subject, and then the tape is pulled horizontally along the wall. The participant stands with the feet together so that his or her back is against the wall. The arms are outstretched laterally and maximally at the level of the shoulders, in contact with the wall, and with the palms facing forward. The tip of the middle (longest) finger (excluding the fingernail) of the right hand is kept in contact with the block, while the zero end of the tape is set at the tip of the middle (longest) finger (excluding the fingernail) of the left hand. Two people (measurers) are necessary, one at the zero end of the tape to be sure the tape end is positioned correctly and the other at the block end to make the reading. The measurement is recorded to the nearest 0.1 cm. Occasionally, a small stool may be required for the measurers to make this measurement on tall subjects (when the measurer is shorter than the study subject). When making this measurement, it is imperative that the participant’s arms be outstretched maximally and that they are held in this position until the reading is taken. Special care must be taken with young children and older individuals as they tend to lower their arms during the measurement.

Please note that there might be high levels of participant discomfort (see Requirements) for the elderly and young children who may not be as flexible.

Personnel and Training Required

Technicians should be trained in the basic techniques of anthropometric measurements.

Equipment Needs

Measurement tape that is at least 2 meters long and block-positioned on a wall where the block can be moved vertically

Requirement CategoryRequired
Major equipment No
Specialized training No
Specialized requirements for biospecimen collection No
Average time of greater than 15 minutes in an unaffected individual No
Mode of Administration

Physical Measurement


Toddler, Child, Adolescent, Adult, Senior


Participant aged 2 years or older

Selection Rationale

This arm span measurement protocol was published in the Anthropometric Standardization Reference Manual (Lohman, Roche, & Martorell, 1988), a commonly used standard for collecting anthropometric variables.


Chinese, English

Logical Observation Identifiers Names and Codes (LOINC) PhenX - arm span protocol 62404-9 LOINC
caDSR Form PhenX PX020101 - Arm Span 5791778 caDSR Form
Derived Variables


Process and Review

The Expert Review Panel #1 reviewed the measures in the Anthropometrics, Diabetes, Physical Activity and Physical Fitness, and Nutrition and Dietary Supplements domains.

Guidance from the ERP includes:

• Added replicate measure language

• Changed unit of measurement

Back-compatible: no changes to Data Dictionary

Previous version in Toolkit archive (link)

Protocol Name from Source

Lohman, T. G., et al, Anthropometric standardization reference manual, 1988


Lohman, T. G., Roche, A. F., Martorell, R. (Eds.). (1988). Anthropometric standardization reference manual. Champaign, IL: Human Kinetics Books.

General References

Forman, M. R., Zhu, Y., Hernandez, L. M., Himes, J. H., Dong, Y., Danish, R. K., . . . Hirschfeld, S. (2014). Arm span and ulnar length are reliable and accurate estimates of recumbent length and height in a multiethnic population of infants and children under 6 years of age. Journal of Nutrition, 144(9), 1480-1487.

Quanjer, P. H., Capderou, A., Mazicioglu, M. M., Aggarwal, A. N., Banik, S. D., Popovic, S., . . . Zelter, M. (2014). All-age relationship between arm span and height in different ethnic groups. European Respiratory Journal, 44(4), 905-912.

Protocol ID


Export Variables
Variable Name Variable IDVariable DescriptiondbGaP Mapping
PX020101010000 Arm Span measured in centimeter, first measurement N/A
PX020101020000 Arm Span measured in centimeter, second more
measurement show less
PX020101030000 Arm Span measured in centimeter, third measurement N/A
PX020101040000 Average Arm Span measurement Variable Mapping
Measure Name

Arm Span

Release Date

March 27, 2009


Measurement of the maximum distance between the extended middle fingers of the right and left hands.


Arm span is highly correlated with stature and may be used to estimate an individual’s stature when height or recumbent length cannot be measured. Because height correlates with lung volume and certain other pulmonary function parameters, arm span can be used as a predictor or surrogate for height in predicting selected pulmonary parameters. In addition, an increased arm-span-to-height ratio can suggest a loss of height such as in kyphosis and kyphoscoliosis, which can in turn be associated with osteopenia and osteoporosis.


Anthropometrics, height, stature

Measure Protocols
Protocol ID Protocol Name
20101 Arm Span

There are no publications listed for this protocol.