Basketball dunk calculator

A dunk calculator answers one question: how much vertical do you need to get your hand and a basketball above the rim? You give it your height, standing reach and current jump, pick a rim height and a dunk type, and it returns the vertical needed to dunk, the smaller jump needed only to touch the rim, and the gap between your jump and each. People ask it in many ways, from “can I dunk” to “vertical needed to dunk”, but every version comes down to the same thing: what number should I train toward?

How the vertical needed to dunk is worked out

The NBA rim sits 10 feet, or 120 inches, above the floor. Your standing reach is how high your fingertips reach flat-footed with one arm raised, and rim height minus reach is the jump that puts your fingertips on the rim. A dunk needs more, because your palm and the ball must finish above the iron. The calculator adds a margin for the dunk type, from 6 in for a basic one-hand dunk up to 14 in for a between-the-legs finish (see all dunk types). Those margins are planning rules of thumb, not an official standard. Subtract your current vertical and the remainder is your gap. A gap of zero or less means your reach clears the target, which still does not promise a dunk, because timing, take-off and ball control sit outside the arithmetic.

Vertical needed to dunk by height

Most people have never measured their standing reach, so height-based estimates lean on a common rule of thumb: reach is about 1.31 times height. The table applies that ratio to a 10 ft rim and a basic margin of 6 in. For more heights, lower rims and other dunk types, see the full vertical-needed tables.

Each extra inch of height adds about 1.31 inches of reach, which comes straight off the jump you need. Arm span matters as much as height: a player with a long wingspan, sometimes called a positive ape index, reaches higher than the ratio predicts and needs less vertical, while shorter arms need more.

Standing reach: measure it or estimate it

Stand flat-footed with your side to a wall, raise the nearer arm straight up and mark your longest fingertip. Measure from the floor to the mark. If you have no wall and tape measure to hand, the Estimate link beside Standing reach multiplies your height by 1.31 as a starting point, and the standing reach calculator does the same on its own page. A measured reach is better, because any error in reach moves the answer by the same amount.

How to measure your vertical jump

The classic method is the wall test, also called the jump-and-reach or Sargent test. Mark your standing reach, jump and touch the wall as high as you can, then measure between the two marks. Take the best of three attempts. A phone in slow motion works too: the height follows from time in the air as g × t² ÷ 8, but a few frames of error at a low frame rate can add inches. The two methods measure slightly different things, since the wall test includes your arm reach, so pick one and keep using it. The vertical jump calculator works out your vert from either test. A running take-off usually beats a standing jump, and most dunks involve an approach, so enter the figure that matches how you will really take off.

Hang time: why a few extra inches matter

The calculator shows the total hang time for the required jump, but only the time spent above dunk height is usable. A jump that only just clears the target leaves a very short window to get the ball over the rim, while a few extra inches widen it a lot. That is one reason players who barely meet the numbers often find the real thing harder than the arithmetic suggests.

Dunk calculator squat: can squat strength predict a dunk?

Some tools claim to turn a squat weight into a vertical jump, usually with coaching coefficients rather than tested formulas. Squat strength does help, because jumping is about producing force quickly, and legs that are strong relative to bodyweight generally go with higher jumps. But speed, tendon stiffness, coordination and technique all matter, and two people with the same squat can jump very differently. This calculator therefore asks for a measured vertical. If your squat improves, re-test your jump every few weeks under the same conditions and enter the new number.

Can short players dunk?

Yes. Spud Webb, at 5′7″, won the 1986 NBA Slam Dunk Contest. Shorter players need a bigger vertical, as the table shows: a 5′4″ player needs about 42.2 in against 26.4 in at 6′4″. Long arms, large hands and good ball control all lower the margin you need, and lower rims are a common way to learn the movement. Youth leagues often use 8 or 9 ft rims, and you can set those heights in the calculator. See can short players dunk for the full numbers.

How to close the gap between your vertical and a dunk

The gap is a training target, not a verdict. Four things move it:

• Build leg strength. Jump squats, Bulgarian split squats and deadlifts develop the force behind a jump.
• Add plyometrics gradually. Box jumps, bounds and depth jumps train fast, springy take-offs, but they load tendons and joints, so progress slowly.
• Improve the take-off. A fast approach with a well-timed last step turns speed into height.
• Practise on a lower rim. Rehearse the dunk at 9 or 8 ft while your vertical builds, then raise it step by step.

Re-test every few weeks, warm up properly and increase jump volume gradually; hard jumping carries injury risk.

Using the calculator

Switch between ft + in, inches and centimetres at any time and your numbers carry over. The optional advanced settings let you replace the dunk margin, add body mass for a jump-energy figure, and note your hand size and experience level for extra context in the results. Everything is calculated in your browser, so your measurements stay on your device.