Deterministic · No AI

LEGO® Technic Gear Ratio Solver

Find ratios, matching gears, compatible pairs, and axle spacing from a Technic gear catalog. Module‑1 math: center studs = (T₁ + T₂) / 16.

Find Matching Gear

Target ratio 5:1 reduction
Best match3 studs

8T → 40T

5:1 (40T / 8T)

Output rotates 5.00× slower; theoretical torque ≈ 5.00×.

Speed 0.2×
Torque 5×

Speed/torque figures assume ideal mesh with no friction or losses. Real Technic builds lose efficiency to friction, axle bend, and imperfect alignment.

Ranked solutions

1 options

How does this work?

Pure geometry — pick teeth counts and stud spacing; no AI. Uses technic_gears.json module-1 distances.

Single pair

  1. Choose driver and driven gear tooth counts from the dropdowns.
  2. Read center distance in studs and the gear ratio.
  3. Use matching mode to find pairs that fit a target stud span.

Compound

  1. Switch to Compound (V2) for multi-stage reductions.
  2. Enter target ratio or total stud span constraints.
  3. Verify each stage against your Technic frame layout.

Formula checks · Module 1

8+24 → 2 studs · 3:1 ✓12+20 → 2 studs · 1.6666666666666667:1 ✓16+16 → 2 studs · 1:1 ✓8+40 → 3 studs · 5:1 ✓12+36 → 3 studs · 3:1 ✓

Gear geometry from technic_gears.json — not AI. Photo identification (if added later) would only identify a part; this solver does the math.