MOVEMENT PHYSICS
Jump Physics Calculator
Convert jump velocity ↔ apex height under any gravity, with variable fall gravity.
PLATFORMER FEEL
Tune the jump arc
Jump physics guide
Jump feel is decided by three numbers: gravity, jump velocity, and how high the character can actually reach. This calculator converts between jump velocity and apex height under any gravity — the exact math behind every platformer from Mario to Hollow Knight.
The two formulas that matter
Apex height = velocity² ÷ (2 × gravity). Jump velocity = √(2 × gravity × height). That is the whole physics of a jump — one quadratic, two directions.
Most engines run gravity around 20–40 units/s² and jump velocities 8–16 units/s, which lands apexes in the 1–4 unit range. Tune height first (level geometry is built to it), then derive velocity from it.
Variable fall gravity is the secret sauce
Games that feel great to jump in rarely use one gravity value. They rise slowly and fall fast — the apex lingers, the landing snaps. That is variable fall gravity: gravity × ~1.5–2 on the way down. It adds weight without making the jump feel floaty.
Tip: Start from feel targets: time-to-apex ~0.25–0.4s, total air time ~0.7–1.0s for a snappy jump. Work backward to get velocity and gravity.
Frequently asked questions
How do I calculate jump height from velocity?
height = v² / (2g). With v = 12 and g = 30, that is 144/60 = 2.4 units.
What is a good jump velocity for a platformer?
8–16 units/s depending on gravity and scale. Pick your apex height first (1–3 units is typical), then solve for velocity.
Why does my jump feel floaty?
Gravity is probably too low relative to jump velocity, or you are using one gravity for the whole arc. Try raising fall gravity to 1.5–2× the rise gravity.
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