How to Dunk a Basketball: The Exact Vertical Jump You Need by Height

Most people think dunking requires being 6'5" or having a 40-inch vertical. Neither is true. Plenty of 5'10" athletes dunk, and the average dunker's vertical is nowhere near 40 inches. The real barrier is that almost nobody knows the actual number they are chasing.

That is the problem. Without knowing your real dunk gap, you train the wrong things. You grind out random jump workouts, plateau, and quit — never realizing you were only four inches away the whole time. The number matters before the program does, because the number tells you whether you need six weeks or six months.

So start there. You can find your exact dunk gap in about 30 seconds using your height and reach, then build a plan around the real figure instead of a guess.

The formula, explained simply

Dunking comes down to one equation. Your required vertical equals the rim height plus the clearance you need, minus your standing reach. The rim is 120 inches. One-hand clearance is about 6 inches. So a player who reaches 96 inches needs a (120 + 6) − 96 = 30-inch vertical.

That is the whole thing. Everything else is just measuring those three numbers accurately.

Why reach beats height

Height gets the attention, but standing reach does the work. Reach is how high you touch flat-footed, and it already includes your arm length and shoulder mobility. Two people who are both 6'0" can have reaches that differ by three or four inches, which changes their required vertical by the same amount.

This is why the calculator asks for reach, not just height. A long-armed 5'11" player can need less vertical than a short-armed 6'2" player. Measure your reach and you stop guessing.

Required vertical by height

Here is the one-hand standing vertical needed at common heights, using an estimated reach of height × 1.33. The running column shows the same target with a typical +4-inch approach bonus.

The running approach is mechanics, not cheating

A one-to-three-step approach adds roughly 3–5 inches of effective vertical over a flat-footed jump. Your run-up builds horizontal speed, and your final plant step redirects that momentum upward. That is real lift, not a trick. If your standing vertical leaves you a few inches short, the approach often closes the gap on its own.

This is why every dunker you have ever watched takes a run-up. They are not showing off. They are using physics.

How far away you actually are

The average untrained adult has a standing vertical of around 20 inches. That sounds discouraging next to the numbers above, but verticals are highly trainable. With structured work — heavy strength training, explosive plyometrics, and approach technique — most people add 10–15 inches over 3–6 months. That progress alone moves a 6'0" athlete from "no chance" to dunking with a running approach.

The takeaway: untrained does not mean stuck. It means you have the most room to grow.

One-hand versus two-hand

One-hand dunks need about 6 inches of clearance over the rim. Two-hand dunks need closer to 9 inches because both arms have to clear it for control. That extra 3 inches is significant — for many players it is the difference between dunking this season and next. Target the one-hand threshold first. Once that feels routine, the two-hand dunk becomes the next milestone rather than the entry fee.

Get your real numbers, train the gap, and pick the approach. The dunk is a math problem before it is an athletic one — and now you know the math.