TOOLS · CALCULATORS

Conveyor Design Calculators

Six first-pass estimators for belt speed, capacity, cross-section, power, tension, idler spacing and idler load — with the full formula shown. Switch units at any time.

Switch units — inputs and results convert together.

01Belt speed

v = π · D · n / 60

—

Typical 1.5–5.0 m/s for bulk handling; higher speeds raise capacity but accelerate cover wear and dust.

How this is derived
  • Belt speed equals the rim speed of the drive pulley: v = ω·R.
  • Angular speed from rpm: ω = 2πn/60, radius R = D/2.
  • Substitute: v = (2πn/60)·(D/2) = π·D·n/60  [m/s].

02Capacity & trough cross-section

Q = (A₁ + A₂) · v · ρ · 3600

—

Steady-state capacity at uniform feed, horizontally. Reduce ~10 % per 10° of incline above 10°. Confirm with full DIN/ISO design.

How this is derived
  • Usable belt width: b = 0.9·B − 0.05 m (CEMA edge clearance).
  • Equal 3-roll set → each roll L = b/3.
  • Trough area (trapezium below the side-roll tops): A₁ = L²·sinλ·(1+cosλ).
  • Surcharge pile on top: A₂ = (L·(1+2cosλ))²·tanβ / 4.
  • Throughput: Q = (A₁+A₂)·v·ρ·3600  [t/h] — the 3600 is s/h; A in m², v in m/s, ρ in t/m³.

03Drive power

P = (Q·H/367 + ω·Q·L/367) / η

—

Indicative only — excludes belt and idler mass and start-up inertia; use for a first motor size, then do the full resistance sum.

How this is derived
  • Material mass flow: ṁ = Q·1000/3600 = Q/3.6 kg/s.
  • Lift power: P₁ = ṁ·g·H/1000 = Q·H·9.81/3600 = Q·H/367 kW.
  • Friction power (main + secondary, lumped as ω ≈ 0.02–0.04): P₂ = ω·Q·L/367 kW.
  • Divide by drive efficiency: P = (P₁+P₂)/η. Add a service factor for start-up.

04Effective belt tension (Te)

Te = 1000 · P / v

—

Te is the running (effective) tension. For belt selection add the wrap-angle factor and the take-up tension — a full DIN 22101 check.

How this is derived
  • Drive power from the previous calculator: P = (Q·H/367 + ω·Q·L/367)/η.
  • Power equals tension times speed: P = Te·v (SI: W = N·m/s), so Te = 1000·P/v N.
  • Te is the effective tension. Peak belt tension also depends on the drive factor e^μα/(e^μα−1) and the take-up setting.
  • Compare with the belt's rated tension × width, and apply the splice efficiency.

05Idler spacing

Rule of thumb by belt width & duty

—

Confirm the chosen spacing against the belt-sag limit f ≤ 1–2 % of spacing and the idler load rating.

How this is derived
  • Carrying spacing narrows as belts get wider and material heavier — to hold belt sag below ~1–2 % of the spacing.
  • Base by width: 1300 mm (B < 800), 1200 mm (800–1200), 1100 mm (B > 1200).
  • Adjust for duty: ×0.9 if ρ > 1.6 t/m³ (heavy ore), ×1.1 if ρ < 0.9 t/m³ (light grain).
  • Return (empty) side runs about twice the carrying spacing.

06Idler load per station

F = (qₘ + w_b) · a · g , qₘ = Q/(3.6·v)

—

Compare F with the idler's rated load for its CEMA class and roll diameter. Cushion the loading point with impact idlers or a buffer bed.

How this is derived
  • Material mass per metre of belt: qₘ = Q·1000/3600/v = Q/(3.6·v) kg/m.
  • Add the belt's own mass per metre w_b (EP belt ≈ 12–18 kg/m).
  • Load on one idler set over its spacing a: F = (qₘ + w_b)·a·g N.
  • For a 3-roll trough the centre and side rolls share F by a distribution factor — check the worst-loaded roll against the CEMA class rating.

Estimates for preliminary sizing only; friction and fill factors are approximate. Detailed DIN/ISO design requires the full resistance sum and material tests.

Need the exact numbers?

These are first-pass estimators. Send us your duty — belt width, material, tonnage, layout — and our engineers return a full DIN/ISO calculation and a component quotation.

Request a full calculation →