BeltLenIn · sizing selection
BeltLenIn v belt open length
Get a belt length before ordering a replacement belt for a two-pulley open drive
Result
L=2C+π(D+d)/2+(D−d)²/(4C) classical open-belt approximation using pitch/OD inputs as entered
How to use this estimate
Open two-pulley belt length approximation L=2C+π(D+d)/2+(D−d)²/(4C) from center distance and pulley diameters (classical geometry screen). Units: Inputs and output in inches; π dimensionless; squared length / length → length. Out of scope as listed on this page. Screening / idealized model only — not a stamped design.
Sources, methodology, and assumptions
Methodology
Open two-pulley belt length approximation L=2C+π(D+d)/2+(D−d)²/(4C) from center distance and pulley diameters (classical geometry screen)
Units check
Inputs and output in inches; π dimensionless; squared length / length → length
Assumptions
Idealized/derived model as scoped; user-supplied inputs.
Out of scope
See MODEL_VALIDITY outOfScope; not a stamped design.
Sources
Unit-context references only — exact model supported by derivation, not org homepages.
Last technically reviewed: 2026-09-11