How to Size an Inclined Vibrating Screen — Step-by-Step Guide with Worked Examples

The 5 Inputs You Need Before Sizing

Before you can size an inclined vibrating screen, you need five pieces of information about your feed and your target product. If any of these are missing, the sizing calculation is a guess.

• Feed rate (Q in t/h): Peak feed to the screen, not average. Always use peak — averaging undersizes screens.
• Particle size distribution (PSD): A sieve analysis of the feed showing % passing each size. Critical for the half-size and oversize correction factors.
• Bulk density (ρ in t/m³) and moisture content: Limestone is 1.5–1.6 t/m³ dry; iron ore can hit 2.5 t/m³. Moisture above 5% needs a separate correction.
• Number of product fractions needed: This determines deck count. Three products → 2-deck. Four products → 3-deck. Five products → 4-deck.
• Open area % of selected screen media: Woven wire mesh runs 50–65%, polyurethane panels 25–45%, rubber panels 30–40%. Use the actual figure for the panel you specify, not a generic value.

The Inclined Screen Capacity Formula

The standard inclined screen capacity formula calculates the required screen area in square metres:

Basic capacity (B)

Basic capacity is the throughput a square metre of clean wire mesh would handle on dry, free-flowing material at sea level with the standard 25 mm aperture as a reference. As aperture size grows, basic capacity goes up almost linearly. Typical values:

The K-factors (correction multipliers)

• K — half-size factor: 1.0 if 25% of feed is half the aperture size; up to 2.0 if 60% is half-size. Half-size material passes easily.
• E — efficiency factor: 1.0 at 95% screening efficiency; 0.8 at 90%; 0.6 at 80%. Most aggregate plants target 90–95%.
• D — deck position factor: 1.0 for top deck; 0.9 for second deck; 0.8 for third deck (because each deck handles a smaller PSD).
• F — oversize factor: 1.0 if 25% of feed is oversize; drops to 0.6 if 80%+ is oversize.
• S — slot/aperture shape: 1.0 for square; 1.15 for slotted (longer apertures pass material faster).
• O — open area factor: Open area / 50%. So 60% open area = 1.2; 35% (PU panel) = 0.7.

Worked Example #1 — 300 t/h Crushed Limestone, 3 Products

Given: 300 t/h crushed limestone, 0–80 mm feed, 4% moisture, 1.6 t/m³ density. Need three products: 0/16 mm, 16/32 mm, 32+ mm. Two cut points → 2-deck inclined screen.

Top deck — 32 mm cut

• Throughput at top deck = 300 t/h (full feed)
• Aperture = 32 mm → B ≈ 14 t/h/m²
• K (half-size, ~30% under 16 mm) ≈ 1.1
• E (target 92%) ≈ 0.9
• D (top deck) = 1.0
• F (oversize ~25%) = 1.0
• S (square wire) = 1.0
• O (60% open area wire) = 1.2
• A = 300 / (14 × 1.1 × 0.9 × 1.0 × 1.0 × 1.0 × 1.2) ≈ 18.0 m²

Wait — that is too much. The correction factors here multiply down the requirement, not up. The combined correction is 14 × 1.1 × 0.9 × 1.2 ≈ 16.6, so A = 300 / 16.6 = 18 m². That is 18 square metres of effective top-deck area. A single STE2470 is 2.4 m × 7.0 m = 16.8 m² per deck — close but slightly undersized. Step up to a single STE2470 with margin OR use a slightly larger model. Practically, either spec works because the correction factors are conservative.

Second deck — 16 mm cut

• Throughput = 300 × (% passing 32 mm) ≈ 300 × 0.75 = 225 t/h
• Aperture = 16 mm → B ≈ 9 t/h/m²
• K ≈ 1.1, E ≈ 0.9, D = 0.9 (second deck), F ≈ 1.0, S = 1.0, O = 1.2
• A = 225 / (9 × 1.1 × 0.9 × 0.9 × 1.0 × 1.0 × 1.2) ≈ 23 m²

The second deck is the limiting deck — it needs more area than the top because the throughput per square metre drops fast when the cut size is small. The required 23 m² confirms an STE2470 (16.8 m² per deck) is undersized for this duty. The correct call is to step up to a larger frame or add a second machine in parallel, or accept lower screening efficiency on the bottom deck.

Worked Example #2 — 150 t/h Granite, 4 Products

Given: 150 t/h crushed granite, 0–60 mm feed, 2% moisture, 1.55 t/m³ density. Need four products: 0/4, 4/8, 8/16, 16+ mm. Three cut points → 3-deck inclined screen.

• Top deck (16 mm cut): 150 t/h, aperture 16 mm. B = 9, K = 1.1, E = 0.9, D = 1.0, F = 1.0, O = 1.2. A = 150 / (9 × 1.1 × 0.9 × 1.2) = 14 m².
• Middle deck (8 mm cut): ~110 t/h. B = 6, K = 1.1, E = 0.9, D = 0.9, F = 1.0, O = 1.2. A = 110 / (6 × 1.1 × 0.9 × 0.9 × 1.2) = 17 m².
• Bottom deck (4 mm cut): ~70 t/h. B = 3.5, K = 1.0, E = 0.9, D = 0.8, F = 1.0, O = 1.0 (need a finer panel — open area drops). A = 70 / (3.5 × 1.0 × 0.9 × 0.8 × 1.0) = 28 m².

The 4 mm bottom deck pushes the required area to 28 m². This is bigger than any single STE model. The pragmatic solutions are: (1) accept 85% screening efficiency on the bottom deck (which lifts the E factor and reduces the requirement); (2) use polyurethane panels on the bottom deck to extend run time (smaller machine, more frequent media changes); (3) split the duty across two screens in parallel; or (4) use a horizontal screen (ETE Series) for the fine bottom-deck duty where elliptical motion gives much higher fine-screening capacity per m².

STE Series Quick-Reference Sizing Table

Approximate capacities for the GELEN STE Series on standard crushed limestone (1.6 t/m³, dry, 50% half-size, woven wire). Use this as a starting point — always verify with the full formula.

The wide capacity range reflects that material type, cut size, and number of decks all swing the realistic throughput by 2× or more. For your specific application send us your feed data — we will run the full sizing calculation and recommend the right STE model.

5 Common Sizing Mistakes (And How to Avoid Them)

• Sizing for average feed instead of peak. Aggregate plants often see 20–40% surges over the average. Always use peak feed, not average.
• Ignoring near-size material. If 25%+ of the feed is within ±25% of the cut size, the half-size factor goes the wrong way and you need significantly more area than the basic formula says.
• Underestimating moisture. Even 5–8% moisture reduces effective screening capacity by 20–30% on standard wire mesh. Above 10% you should switch to polyurethane or rubber panels and plan for wet screening with spray bars.
• Wrong open area figure. PU panels (35%) have very different open area than woven wire (60%). Using the wrong figure can over- or undersize the screen by 30%.
• Sizing the top deck instead of the bottom. The smallest cut almost always sets the required area. Size for the bottom deck, not the top.

FAQ

• Should I use the basic formula or simulation software? For 95% of standard aggregate plants, the basic formula with K-factors is accurate within 10–15% — close enough to specify the right size class. Simulation software helps when feed is unusual (very wet, very fine, very hot) or when you need to predict screen performance over a range of operating conditions.
• How much margin should I add? Size for 110–120% of your peak feed rate. This covers feed gradation drift, seasonal moisture, and progressive media wear over the service cycle.
• Does the formula work for wet screening? Yes, but the half-size factor changes. Wet screening with spray bars effectively increases the half-size fraction (water carries fines through faster), which reduces required area by 20–30%.
• What about banana screens? Banana screens (multi-slope) have much higher capacity per m² because the steep upper section accelerates the material, but they cost more and require more headroom. See the banana vs inclined comparison.
• Can I use this for grizzly scalping? Grizzly scalping screens (like the ITE Series) use the same formula but with different basic capacity values for the very large apertures (typically 50–200 mm).

Get a Custom Sizing Calculation

Send us your feed PSD, peak tonnage, moisture content, density, and required product fractions — we will run the full calculation and recommend the right STE Series model, deck count, screen media, and operating settings for your application.

Related guides:

• Inclined Vibrating Screens — Complete Guide
• Inclined vs Horizontal vs Banana Screen
• Screen Media Selection for Inclined Screens
• Inclined Screen Applications by Industry
• Prevent Screen Blinding & Pegging
• Vibrating Screen Maintenance Schedule