Welcome to

---

Vibrating Screen Sizing Guide + Free Excel Calculator

Learn how to size vibrating screens step by step using the VSMA method. Ideal for mining and processing professionals—includes a free Excel calculator.

Follow us on Twitter 
Question, remark ? Contact us at admin@powderprocess.net

---

Section summary
1. Vibrating screen sizing calculation methodology STEP by STEP
2. Vibrating screen sizing Excel calculator

---

This page provides a detailed methodology for calculating the size of vibrating screens, essential for optimizing efficiency and productivity in mining, quarrying, and mineral processing operations. The calculations are based on a formula developed by the Vibrating Screen Manufacturers Association (VSMA), which incorporates various factors to ensure accurate and reliable results.

The process involves analyzing feed characteristics, calculating key parameters, adjusting for specific conditions, and applying the VSMA formula to determine the required screening area. This guide is designed to assist professional engineers in accurately sizing vibrating screens for their operations.

By following the step-by-step instructions outlined below, engineers will be able to:

1. Analyze Feed Characteristics: Understand the size distribution and bulk density of the feed material.

1. Calculate Key Parameters: Determine factors such as the flow rate of material, oversize and half-size percentages, and screening efficiency.

1. Adjust for Specific Conditions: Account for variables like wet screening, material weight, and the shape of screen openings.

1. Apply the VSMA Formula: Use the formula to calculate the required screening area.

Additionally, an Excel calculator is provided to simplify the process, allowing engineers to input their specific parameters and obtain precise results efficiently.

This page aims to equip engineers with the knowledge and tools necessary to accurately size vibrating screens, ensuring optimal screening processes and operational efficiency.

2. Vibrating screen sizing calculation methodology STEP by STEP

How to determine the size required for a vibrating screen ?

The calculation is based on a formula given by VSMA, this is based on correlations determined by an association of vibrating screen manufacturers :

Screening Area (ft²) = U / (A x B x C x D x E x F x G x H x J)

Where:

• U = Amount in STPH of material in feed to deck that is smaller than a specified aperture
• A = Basic capacity (STPH)
• B = Oversize
• C = Halfsize
• D = Deck location
• E = Wet screening
• F = Material weight
• G = Open area of media
• H = Shape of opening
• J = Efficiency

Factor	Explanation
A	Predetermined rate of material in STPH through a square foot of a specified opening when feed to deck contains 25% oversize (factor B) and 40% halfsize (factor C) Basic Operation conditions : - feed to deck contains 25% oversize and 40% halfsize - Feed is granular free flowing material - Material weighs 100 lb/cu.ft - Operating slope of the screen inclined screen 18-20° with flow rotation ; horizontal screen 0° - Objective screening efficiency = 95%
B	Actual % of material in feed to deck that is larger than a specified aperture (adjusts factor A to suit actual conditions)
C	Actual % of material in feed to deck that is one half the size of a specified aperture (adjusts factor A to suit actual conditions)
D	Applies for multiple deck screens. Total screening area is available for top deck separation. Time delay for material to pass to deck and 2nd or 3rd deck leaves less effective area available. This factor is expressed in a % of the top deck effective area.
E	Applies when the water is sprayed on the material as it moves down the screening deck (typically 5-7 GPM per STPH of solids).
F	Applies for weights other than 100 lb/cu.ft, it is calculated as lb/cu.ft (actual) / 100
G	Applies when the open area of the screening surface is less than the reference used for factor A
H	applies when rectangular opening are used. Slotted or oblong openings will pass more material per square foot than square opening.
J	Applies when the target screening efficiency is < 95%

Step 1 : Define the characteristics of your feed

It is important to analyse 1st the characteristics of the feed, especially :

- The size distribution and especially the % of the feed that is larger than the aperture you consider, and the % of the feed that is halft of the size of the aperture you consider

- The bulk density of the feed material

Step 2 : Calculate U which is the flowrate of material smaller than the aperture considered

You have defined the size distribution of the feed, so you know the %weight of material whose size is < than the aperture. Multiplying by the total feed flowrate will give the parameter U.

Step 3 : Calculate the parameter A

Use the following table based on the target aperture

Surface Square opening (inch)	% Open Area	STPH Passing / sq ft (parameter A)
4	75.00%	7.69
3 1/2	77.00%	7.03
3	74.00%	6.17
2 3/4	74.00%	5.85
2 1/2	72.00%	5.52
2	71.00%	4.9
1 3/4	68.00%	4.51
1 1/2	69.00%	4.2
1 1/4	66.00%	3.89
1	64.00%	3.56
7/8	63.00%	3.38
3/4	61.00%	3.08
5/8	59.00%	2.82
1/2	54.00%	2.47
3/8	51.00%	2.08
1/4	46.00%	1.6
3/16	45.00%	1.27
1/8	40.00%	0.95
3/32	45.00%	0.76
1/16	37.00%	0.58
1/32	41.00%	0.39

Step 4 : Calculate parameter B

Determine the % of oversize vs the aperture used in the screen. To note that the factor B is equal to 1 for 25% oversize as it is the reference conditions.

%oversize	Factor B
5	1.21
10	1.13
15	1.08
20	1.02
25	1
30	0.96
35	0.92
40	0.88
45	0.84
50	0.79
55	0.75
60	0.7
65	0.66
70	0.62
75	0.58
80	0.53
85	0.5
90	0.46
95	0.33

Step 5 : Calculate the factor C

Factor C is determined by measuring the % of half size vs the screen aperture in the feed. Note that factor C is equal to 1 for 40% as it is the reference conditions.

%halfsize	Factor C
0	0.4
5	0.45
10	0.5
15	0.55
20	0.6
25	0.7
30	0.8
35	0.9
40	1
45	1.1
50	1.2
55	1.3
60	1.4
65	1.55
70	1.7
75	1.85
80	2
85	2.2
90	2.4

Step 6 : Calculate parameter D

• For top deck : D = 1
• For second deck : D = 0.9
• For third deck : D = 0.8

Step 7 : Calculate the factor E

Apply only when water is sprayed. Dependent on the screen opening.

Opening (inch)	Factor E
1/32	1
1/16	1.25
1/8	2
3/16	2.5
1/4	2
3/8	1.75
1/2	1.4
3/4	1.3
1	1.25

Step 8 : Calculate the factor F

Measure the bulk density of the incoming material. Then use the table to determine F,

lb/cu.ft	Factor F
150	1.5
125	1.25
100	1
90	0.9
80	0.8
75	0.75
70	0.7
60	0.6
50	0.5
30	0.3

Step 9 : Calculate the factor G

G is actually defined as the following ratio :

(% open area of screen surface used in the application) / (% open area in reference chart of factor A, for same aperture)

Step 10 : Calculate the factor H

H depends on the shape of the openings of the actual screen used :

• Square : 1
• Short slot (3 to 4 times width) : 1.15
• Long slot (more than 4 times width) : 1.20

Step 11 : Calculate the factor J

Based on the screening actual target screening efficiency. Note that 95% is 1 as it is the reference condition.

Efficiency considered (%)	Factor J
95.00%	1
90.00%	1.15
85.00%	1.35
80.00%	1.5
75.00%	1.7
70.00%	1.9

Step 12 : Calculate the actual capacity of the screen

Screening Area (ft²) = U / (A x B x C x D x E x F x G x H x J)

Step 13 : Calculate that the overall screen area, combined with the width of the screen considered gives an acceptable discharge end depth

It is key that the depth of the material bed at the end of the vibrating screen be not too high (typicall < 4*aperture size). Use this calculator (vibrating screen DBD - Discharge End Bed Depth Excel calculator) to make sure it is acceptable, if not, redefine the screen width.

2. Vibrating screen sizing Excel calculator

What are the key process parameters to consider ?

Please access here the vibrating screen sizing Free Excel calculation tool : tool access

Warning : this calculator is provided to illustrate the concepts mentioned in this webpage, it is not intended for detail design. It is not a commercial product, no guarantee is given on the results. Please consult a reputable designer for all detail design you may need.

---

Sources

VSMA