A conveyor belt runs at the surface speed of its drive roller — every revolution feeds out exactly one roller circumference of belt. So the belt speed follows straight from the roller diameter and its RPM. Once you know the speed, the throughput is just how much material sits on each metre of belt, carried past a point at that speed; and the travel time for any item is the conveyor length divided by the speed. Those three numbers size a conveyor for a target tonnes-per-hour and process time.
Reviewed: June 19, 2026 · Author: Naveen P N, Founder — AI Calculator · Verified against: belt-conveyor kinematics (no-slip drive).
The conveyor equations
The π·D·N form gives metres per minute when the diameter is in metres and N in rev per minute — divide by 60 for m/s. The throughput conversion factor 3.6 turns kilograms per second into tonnes per hour (kg/s × 3600 ÷ 1000). Belt load per metre is the mass of product riding on each metre of belt; multiply it by the belt speed and you have the mass crossing any point each second.
Worked example — a packing-line conveyor
Scenario: A 250 mm drive roller turns at 60 rpm; the belt carries 40 kg per metre over a 30 m run.
The belt moves at 0.79 m/s and shifts about 113 tonnes per hour, while any single item takes ~38 seconds to ride the 30 m length. To raise capacity you could speed the roller up — 90 rpm lifts the belt to 1.18 m/s and throughput to ~170 t/h — but the travel time then shrinks to ~25 s, which matters if the belt doubles as a cooling or inspection station.
Frequently Asked Questions
v = π × D × N (roller diameter × rpm). A 250 mm roller at 60 rpm ≈ 47 m/min (0.79 m/s).
Q = belt load (kg/m) × speed (m/s) × 3.6. 40 kg/m at 0.79 m/s ≈ 113 t/h.
Packing lines 0.1–0.5 m/s; bulk material 1–4 m/s; long overland/mining belts 5+ m/s. Faster = more wear and dust.
Directly proportional — double the roller diameter, double the belt speed at the same RPM. Roller size and gearbox are chosen together.
time = length / speed. A 30 m belt at 0.79 m/s ≈ 38 s — important for cooling, drying or inspection stations.