Free Jump Arc Calculator for Platformers

From kinematic equations: v = √(2 × g × h) where v is initial velocity, g is gravity and h is jump height. Most platformers prefer to define jumps by height (h) and time to apex (t), then derive:

gravity g = 2 × h / t²
initial velocity v = 2 × h / t

This calculator runs both formulas for you and exports the right values for Unity, Godot or Unreal.

Three changes turn a floaty platformer into a snappy one:

1. Short time to apex. Typical "good feel": 0.3–0.45 s. Anything longer feels floaty.
2. Asymmetric gravity. Fall faster than you rise — multiply fall gravity by 1.5–2.5× rise gravity.
3. Forgiveness timers. Add coyote time (0.05–0.15 s of jump grace after leaving an edge) and jump buffer (0.1–0.2 s of jump input pre-queue before landing).

The calculator suggests sensible coyote-time and jump-buffer ranges based on the timings you pick.

Most arcade and modern platformers use different gravity for rising vs falling. Falling faster than you rise makes jumps feel responsive and reduces the floaty/hang-time effect. Typical multiplier is 1.5–2.5× — Super Mario uses ~2×, Celeste uses ~2.5×. Set the fall multiplier in the calculator and watch the arc shape change.

On jump button release, cut the upward velocity. The cleanest implementation: when the player releases the jump button while moving upward, set velocity.y = max(velocity.y * cutFactor, 0) with cutFactor around 0.5. The calculator outputs a recommended cut velocity for the height range you defined.

Coyote time: remember "was grounded recently" with a timer. When the player presses jump within ~100 ms of leaving an edge, allow the jump.

Jump buffer: when the player presses jump in the air, remember the press for ~150 ms. If they land within that window, trigger the jump immediately.

Both are 5–10 lines of code each and dramatically improve perceived responsiveness. The calculator suggests ranges based on your apex timing.

Yes — the code export panel ships templates for all three:
• Unity: Rigidbody2D with gravity scale, variable jump cut, and asymmetric fall.
• Godot 4: CharacterBody2D with move_and_slide, gravity from the calculator.
• Unreal: Character / CharacterMovementComponent JumpZVelocity, GravityScale and FallingLateralFriction values.
Each template is copy-paste ready with your computed values filled in.

Tiles, pixels and metres. Pick whatever matches your engine: Unity defaults to metres, Godot to pixels, retro tile-based platformers prefer tiles. The arc preview updates with your chosen unit and the exported code uses the same scale.

Two common Unity gotchas:

1. Rigidbody2D gravity scale ≠ Project gravity. Unity's Physics2D gravity is global; per-Rigidbody2D gravityScale multiplies it. Set the calculator's gravity value with the project setting AND set gravityScale to 1, OR keep project gravity at default and use gravityScale to tune.

2. Fixed timestep. Physics runs on FixedUpdate. Apply jump in FixedUpdate (or set velocity in Update only on the press frame). Reading input in FixedUpdate misses presses; reading velocity changes in Update gets stomped by physics.

Yes — click Share Configuration and the URL encodes every input (height, time to apex, asymmetric gravity, double jump, unit). Anyone who opens the link sees the same arc and the same exported code.

No. The calculator runs entirely in your browser. Nothing is uploaded; no analytics on your inputs.