Arm Span Calculator - Ape Index & Wingspan Measurement

What is Arm Span and Why Does It Matter?

Arm span measurement is the distance between fingertips when the arms are outstretched. It is a simple measure that is important in the anthropometrical profiling of athletes in many sports in which reach is important, such as rowing, swimming and basketball. The ratio of arm span to height, commonly called the "ape index," has become particularly important in sports science as it can provide insights into an athlete's potential advantages in specific sports.

Research by Robert J. Wood, PhD in Exercise Physiology from the University of Western Australia and founder of Topend Sports, indicates that while arm span typically equals height in the general population, significant variations exist among elite athletes. These variations can provide measurable advantages in sports requiring reach, such as basketball rebounding, swimming stroke length, or boxing striking range.

Understanding Ape Index

The term "ape index" originated from rock climbing communities but has since been adopted across multiple sports. It refers to the comparison between your arm span and height. There are two methods to calculate this:

Ratio Method: Divide arm span by height. A result of 1.0 is neutral (equal proportions), above 1.0 indicates longer arms (positive ape index), and below 1.0 indicates shorter arms (negative ape index). For example, if your arm span is 180cm and height is 175cm, your ape index ratio is 1.029.

Difference Method: Subtract height from arm span. A positive number means longer arms, negative means shorter arms, and zero is neutral. Using the same example, 180cm - 175cm = +5cm ape index.

According to sports science expert Robert Wood, who has analyzed sports performance data for over 25 years, the average ape index in the general population is approximately 1.0 (or 0cm difference), though this varies by ethnicity, age, and sex.

Arm Span Measurement Protocol

Test purpose: To measure arm length, as long arms may be advantageous for some sports which involve reaching and tackling.

Equipment required: ruler or tape measure, wall.

Pre-test: Explain the test procedures to the subject. Perform screening of health risks and obtain informed consent. Prepare forms and record basic information such as age, height, body weight, gender, test conditions. Ensure that the subject is adequately warmed-up. See more details of pre-test procedures.

Procedure: facing away from the wall, with back and buttocks touching the wall, the arms are stretched out horizontally. Measure from one furthermost finger tip to the other.

Results: The arm length measures can be compared to the person's height. On average, arm span should be about equal to height. By subtracting a measurement for shoulder width from this measurement you can get a measure of average arm length. Olympic swimming champion Michael Phelps may have a significant advantage due to his exceptional arm span measurement. His arm span was measured at 203cm, 10cm more than his stature (he also has big feet!).

measuring arm span

Advantages: very low cost, simple and quick test

Other comments: It is important for the subject to fully stretch to get the maximum reach, and that the arms are held exactly horizontally. To assist in keeping the outstretched arms horizontal, use a wall that has horizontal lines already on it such as a brick wall. Also measure out from a corner or wall protrusion so that one hand can be stable and all measurements are away from it.

Arm Span and Height Ratio in Different Sports

The arm span to height ratio has different implications across various sports. Understanding these sport-specific applications can help athletes and coaches optimize training approaches and leverage natural advantages.

Basketball

In basketball, a positive ape index is highly valued. Research indicates that the average NBA player has an ape index ratio of approximately 1.063, meaning their wingspan is 6.3% longer than their height. This advantage is crucial for:

• Defensive Play: Longer wingspans allow players to contest shots more effectively and intercept passes
• Rebounding: Extended reach helps secure rebounds over opponents
• Shooting: Taller release points make it harder for defenders to block shots
• Dribbling and Ball Handling: Greater reach allows better ball protection when closely guarded

Notable examples include Kevin Durant (208cm height, 228cm wingspan, 1.096 ratio) and Giannis Antetokounmpo, both of whom use their exceptional wingspans to dominate defensively and offensively.

Swimming

According to data compiled by Robert Wood, PhD, swimmers with longer arm spans can achieve longer stroke lengths, reducing the number of strokes needed per lap and potentially increasing speed with less energy expenditure. Michael Phelps, with his 203cm wingspan compared to 193cm height (1.052 ratio), exemplifies this advantage. His longer arms act like paddles, providing:

• Greater propulsion per stroke
• Reduced stroke count over distance
• More efficient energy use during long events
• Better reach during turns and finishes

Combat Sports (Boxing, MMA)

In boxing and mixed martial arts, arm span directly translates to striking range. Fighters with positive ape indices can strike opponents while remaining outside their opponent's reach. Jon Jones (193cm height, 215cm wingspan, 1.114 ratio) has used this 22cm advantage to maintain distance and control fights throughout his UFC career. Benefits include:

• Ability to hit without being hit
• Better defensive coverage with extended guard
• Control of fighting distance
• Advantage in clinch situations

Rock Climbing

While climbing communities popularized the term "ape index," research shows mixed results on its importance. Some elite climbers have positive ape indices (Daniel Woods at 1.058), while others like Adam Ondra have neutral ratios (1.000). The relationship is complex:

• Advantages: Reaching distant holds, maintaining balance on steep terrain
• Disadvantages: Longer arms mean greater distance from the wall, requiring more core strength
• Reality: Technique, finger strength, and flexibility matter more than proportions

Rowing

Rowers benefit from longer arm spans as they can achieve longer stroke lengths, improving leverage and power application. The longer reach allows rowers to:

• Catch water earlier in the stroke
• Maintain power through a longer pull
• Generate more boat speed per stroke

Volleyball

Extended reach is crucial for volleyball players, particularly in blocking and attacking. A positive ape index provides:

• Higher blocking point at the net
• Greater attacking angles on spikes
• Improved serving leverage
• Better defensive range

Powerlifting and Weightlifting

Interestingly, shorter arms (negative ape index) can be advantageous in certain lifts. In the bench press, shorter arms mean a shorter range of motion, potentially allowing for heavier lifts. However, in deadlifts, longer arms reduce the distance the bar must travel, providing an advantage. Elite powerlifters exist across the full spectrum of ape indices.

Does Ape Index Predict Athletic Success?

Despite the apparent advantages of specific arm span ratios in certain sports, research shows that ape index alone does not predict athletic performance or success. Multiple studies have found:

• Elite athletes exist across all ape index ranges
• Trainable factors (strength, technique, flexibility) matter more than proportions
• Many world champions have negative or neutral ape indices
• Sport-specific skills trump body proportions

Examples of successful athletes with various ape indices:

• Lynn Hill (legendary climber): 1.0 ratio (neutral)
• Adam Ondra (arguably greatest climber): 1.005 ratio (nearly neutral)
• Desmond Bane (NBA player): 0.985 ratio (negative), nicknamed "T-Rex" but still highly successful

How to Improve Performance Regardless of Ape Index

While body proportions provide some advantages, athletic success depends primarily on trainable factors. Here's how athletes can optimize performance regardless of their ape index:

For Athletes with Positive Ape Index

Basketball: Focus on defensive positioning and shot-blocking techniques. Train footwork to maximize reach advantages. Practice catch-and-shoot scenarios from extended positions.

Swimming: Work on stroke efficiency to maximize propulsion per stroke. Focus on reducing drag and maintaining streamlined body position. Practice distance-per-stroke drills.

Combat Sports: Develop jab and range-control techniques. Practice maintaining distance while capitalizing on reach advantage. Work on defensive footwork.

For Athletes with Negative Ape Index

Basketball: Develop exceptional footwork and positioning. Focus on body positioning for rebounds. Train explosive vertical jump ability to compensate for reach.

Powerlifting: Leverage shorter range of motion in bench press. Focus on building maximum strength in optimal leverages.

Gymnastics: Utilize compact proportions for tighter rotations. Focus on precision and control in movements.

For Athletes with Neutral Ape Index

All Sports: Your proportions are versatile across sports. Focus on sport-specific skills, conditioning, and technique refinement. Success is entirely dependent on training quality and dedication.

Historical and Scientific Background

The concept of arm span equaling height dates to Roman times around 15 BC when architect and engineer Vitruvius Pollio described a "well made man" having an arm span equal to his height. Leonardo da Vinci later illustrated this concept in his famous drawing "The Vitruvian Man" (circa 1492), depicting the ideal human proportions with a 1:1 arm span to height ratio.

Modern anthropometric research has shown that while 1:1 proportions are common, significant variation exists across populations. Factors affecting arm span to height ratio include:

• Ethnicity: Different populations show varying average ratios
• Age: Ratios change through childhood and adolescence, reaching adult proportions around age 12-14
• Sex: Males typically have slightly higher ratios than females
• Genetics: Individual variation within populations is significant

Arm Span in Medical Assessment

Beyond sports, arm span measurements serve important medical purposes. Arm span can be used to estimate height in individuals who cannot stand due to scoliosis, osteoporosis, amputations, or being confined to wheelchairs. Additionally, abnormal arm span to height ratios can indicate certain medical conditions:

• Marfan Syndrome: Characterized by unusually long limbs and positive ape index
• Achondroplasia: Results in shorter limbs and negative ape index
• SHOX Gene Deficiency: Affects bone growth and arm proportions
• Height Loss: Increases in ape index ratio can indicate conditions causing height loss like osteoporosis

Standard medical formulas exist to predict height from arm span, accounting for age, sex, and ethnicity. The most commonly used formula multiplies arm span by approximately 0.98-1.02 depending on population characteristics.

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