Belt & Pulley Calculator

Two-pulley belt drive calculator for belt length, pulley ratio, RPM, center distance, and belt wrap. Belt & Pulley Calculator sizes an open belt drive with two pulleys. Enter the values you already know—driving and driven pulley diameters, RPM, center distance, or belt length—and the app solves the rest. A scaled drawing animates the belt path so you can check wrap, ratio, and layout before you cut or order a belt. BELT LENGTH & PULLEY RATIO • Belt length from pulley diameters and center distance • Center distance from pulley diameters and belt length • Pulley ratio from diameters or from driving and driven RPM • Missing pulley diameter or RPM from the speed ratio • Belt speed from driving pulley diameter and RPM • Belt contact angle (wrap) and contact length on each pulley • Pulley gap between the two pulleys WHO IT IS FOR • Mechanics replacing a belt — get length from the pulleys still on the machine • Engineers laying out a two-pulley belt drive, sheave sizes, and center distance • Motor and machinery work — match driven RPM to pulley diameters • Students and labs — see belt wrap and contact length, not only a ratio WHY THIS BELT CALCULATOR People look up a pulley calculator, belt calculator, belt length calculator, or belt drive calculator for the same job: two pulleys and the belt between them. • Live two-pulley visualization with animation • Angle units (degrees or radians) and display precision you control • Runs on the device — use it offline in the shop or on the floor • One-time purchase — no ads, no subscription From Engineering Kit, publisher of Chain & Sprocket Calculator and other mechanism tools. This app models an open two-pulley belt drive using pitch diameters (the same geometry used for flat belts and V-belt pitch length). It is not a block-and-tackle / mechanical-advantage calculator, and it does not pick standard V-belt sections or horsepower ratings.