Ape index calculator

How your ape index is calculated

The calculator works from two numbers: your height and your wingspan, also called your arm span, measured fingertip to fingertip with both arms held out to the sides at shoulder height. From those it gives you the ape index in two forms, a difference in centimetres or inches, and a ratio.

The difference

Wingspan minus height. A 175 cm person with a 178 cm wingspan has a difference of 178 minus 175, which is plus 3 cm. A 170 cm person with a 166 cm wingspan has a difference of 166 minus 170, which is minus 4 cm.

The ratio

Wingspan divided by height. For the first example, 178 divided by 175 gives 1.017. For the second, 166 divided by 170 gives 0.976. A ratio of exactly 1.00 means your wingspan matches your height exactly.

Reading the label

A positive ape index means your wingspan is longer than your height, a ratio above 1.00. A negative ape index means the opposite, a ratio below 1.00. A difference of 1 cm or less either way is labelled neutral. That cut-off is this calculator's own convention, not a published one: a difference that small is about the size of normal measurement variation.

What the ape index is, and where the term comes from

The ape index compares how far your arms reach when spread out sideways with how tall you stand. Most people are close to a 1 to 1 ratio, wingspan roughly equal to height. Apes have a far greater wingspan relative to their height than humans do, which is where the informal name comes from.

The term is used mainly in climbing gyms and climbing forums, as informal shorthand for reach relative to height, and it has spread from there into general fitness and sports conversation. The underlying idea is much older than the slang: the Roman architect and engineer Vitruvius described a well proportioned man as having an arm span equal to his height, a proportion Leonardo da Vinci later illustrated in the Vitruvian Man.

There is nothing special about ape index as a body measurement in itself. It is simply a convenient way of expressing how your reach compares with your height, and it is most useful in contexts, like climbing, boxing or basketball, where reach for a given height matters for how a sport is actually played.

Ape index at a glance

The table shows how the label and the ratio change as wingspan moves away from height, using a 175 cm (68.9 in) height as the reference point. Your own numbers plug into the calculator above; this is just to show the scale involved.

Why the ape index matters in climbing

The reasoning climbers give is straightforward: a longer reach for a given height lets you get to a hold further away without needing your feet to travel as far first, which matters on routes and boulder problems where holds are spaced generously apart. What the research actually shows is more mixed than that reasoning alone suggests.

Tomaszewski, Gajewski and Lewandowska (2011) measured 21 male competitive climbers and compared them with reference data for 165 untrained students. The climbers had a significantly higher average ape index, 1.05 against 1.02. Within the climbers themselves, ape index tended to correlate with self-reported climbing ability without reaching significance (r equals 0.397, p equals 0.083), and the authors put the low correlation down to how little ape index varied among the climbers (standard deviation 0.02).

Ozimek and colleagues (2017) compared 6 elite climbers (grade 8b to 8c) with 14 advanced climbers (grade 7c+ to 8a). Arm span, ape index (1.01 against 1.02) and upper limb length did not differ significantly between the two groups; what did differ was finger strength and arm endurance, both higher in the elite group. In that small sample, ape index did not separate the very best from the merely very good.

Put together, the honest summary is that climbers as a group tend to have a longer reach for their height than non-climbers, but within a group of people who already climb hard, the one study here found finger strength and arm endurance, not ape index, separated the best climbers from the rest.

Ape index in swimming, boxing and basketball

Outside climbing, ape index comes up most often as a reasoning tool rather than a measured predictor, and it is worth being clear about that distinction.

Swimming

A longer arm span lengthens the distance each stroke pulls through the water, which is the reasoning behind why long limbed swimmers are often mentioned when this topic comes up. Swimming performance depends on a long list of other factors too, including technique, ankle flexibility and lung capacity, and there is no controlled research isolating how much of a swimmer's performance ape index alone explains.

Boxing

A longer reach lets a boxer land a jab or straight punch from further away, while staying outside the range of the opponent's own return. This is basic geometry rather than a tested performance finding: two boxers with identical reach can differ hugely in output based on timing, footwork and power.

Basketball

A longer wingspan extends a player's effective reach for rebounding, shot blocking and passing lanes without adding actual height, which is why basketball scouts record wingspan alongside height at pre draft testing. As with the other sports here, this explains why the measurement is tracked, not that it alone determines who succeeds.

Ape index, the deadlift and the bench press

Ape index also comes up in strength training discussions, usually framed around the deadlift and the bench press. The reasoning below is mechanical leverage logic, not a specific measured study result linking ape index to how much weight someone lifts.

Deadlift

Longer arms relative to torso length mean less forward hip hinge is needed to reach the bar on the floor, which can shorten the distance the bar has to travel to lockout. Shorter arms for the same height typically require more forward lean to reach the bar, lengthening the pull. This is one reason a high ape index is commonly discussed as an advantage for the deadlift specifically.

Bench press

The same long arms work against you here. A longer arm span means the bar has further to travel from the chest to a locked out elbow, so for a given level of pressing strength, a longer bar path generally means a lower number on the bar. This is part of why lifters with a notably positive ape index are commonly said to bench relatively less for their build than they deadlift.

Grip width, torso length and individual technique all interact with arm length too, so treat this as a reasonable explanation for a pattern many lifters notice, not a fixed rule that predicts any one person's numbers. To compare your lifts with others at your body weight, see the strength standards calculator.

How to measure your wingspan properly

Wingspan, also called arm span, is measured fingertip to fingertip with both arms extended straight out to the sides at shoulder height, palms facing forward.

Step by step

Stand with your back against a flat wall, arms raised to shoulder height and extended as far as comfortable without straining or locking the elbows. Have someone else measure straight across from the tip of one middle finger to the tip of the other with a tape measure, or mark both fingertip positions on the wall and measure the distance between the marks afterwards on your own.

Getting a reliable number

Keep your shoulders relaxed rather than shrugged up, since a shrug adds height to your arm position without genuinely lengthening your reach. Take two or three measurements and use the average if they differ by more than a centimetre or so, which is normal.

Measure your height the same day, standing straight against a wall without shoes, for the most accurate ape index. Measuring height and wingspan weeks apart, or after very different amounts of sleep or activity, adds small errors that show up as an artificially inflated or reduced ape index.

What counts as an average ape index, and how it varies

There is no single correct average ape index, because the ratio moves with sex, age and population group.

Quanjer and colleagues (2014) built prediction equations from nearly 14,000 people aged 5 to 99 at nine centres in China, Europe, Ghana, India and Iran, and found the arm span to height ratio is higher in men than in women, varies nonlinearly with age across the lifespan, and differs significantly between the sites, which clustered into four groups: Asia, Europe, Ghana and Iran.

Reeves, Varakamin and Henry (1996) measured 553 young adults and found arm span was significantly different from height specifically in Afro-Caribbean men and women and in Asian men, concluding arm span is not always an appropriate stand in for height, precisely because the relationship between the two is not one fixed number worldwide.

One concrete data point: Tomaszewski and colleagues (2011) report an average ape index of 1.02 for 165 untrained students, close to the roughly 1 to 1 proportion Vitruvius described. The estimate mode above multiplies your height by 1.01 and shows a range of 0.97 to 1.03 times your height. Both numbers are this calculator's own choices, a round figure near 1.00 with a margin either side; no study cited here gives them. Because the real ratio varies with sex, age and population, treat the estimate as a rough guide and measure when you can.

Common mistakes

Shrugging the shoulders while measuring wingspan. It raises your arm position without genuinely lengthening your reach, and inflates the measurement.

Measuring height and wingspan on different days. Small differences in shoes, posture or time of day between the two measurements show up as an ape index that is not really there.

Reading too much into a small ape index. A ratio of 1.01 against 1.00 is 1.75 cm on a 175 cm person, not far from the centimetre or so that repeat measurements of the same person can differ by.

Assuming ape index alone decides performance. Ozimek et al. (2017) found ape index did not differ significantly between elite and advanced climbers in a sample of 20. It is one factor among many, not a verdict.

Comparing your number to an athlete's figure found online. Many circulating athlete ape index numbers are not from verified measurements. Compare your own trend over time, or against the general population figures above, instead.

How coaches use an ape index calculator

For a coach working with climbers or lifters, arm span and ape index are a quick anthropometric note worth having on file alongside height and weight. They help explain why two clients with the same squat depth or the same deadlift can have very different bar paths, or why one client naturally reaches a climbing hold a training partner has to jump for.

Scraler keeps that kind of note on a client's profile alongside their training history, so it is there the next time you programme a block or set a technique cue, rather than sitting in a separate spreadsheet. See client management for keeping these details with the rest of a client's record, and workout programming for building sessions around what a client's build actually favours.