ECalc

Engineering calculators & reference


Belt Center-to-Center

HTD timing-belt center distance — solve for distance from belt teeth, or teeth from a target distance.

C = (P/8)·[(2L − z₁ − z₂) + √((2L − z₁ − z₂)² − (8/π²)(z₂ − z₁)²)]

170.00 mm / 6.693 in

Notes

  • HTD pitches: 3M = 3 mm, 5M = 5 mm. Belt length is its tooth count (teeth × pitch).
  • Result is shown in mm and inches. Solving for length rounds up to the next whole tooth — then snap to an actual stocked belt tooth count.
  • Same closed-form geometry as roller chain; belts just need a whole-tooth count, not an even one.