How do you calculate screening loss?

Divide rejected material by total feed and multiply by 100. With 9 tons rejected from 85 tons of feed that is 9/85 x 100 = 10.59% screening loss.

What is a good screening loss rate?

It depends on the cut and material, but for well-graded minerals 5 to 10% is typical. The example's 10.59% sits just above a 12% ceiling-no, slightly under, with a 1.41 percentage-point cushion to the 12% target.

Screening loss vs screening efficiency, what is the difference?

Screening efficiency measures how well undersize passes the deck; screening loss measures how much total feed is rejected. You can have high efficiency yet high loss if the feed simply contains a lot of off-spec material.

Why is my screening loss climbing?

Common causes are blinded or pegged apertures, worn or stretched screen cloth, an overloaded deck, or a drifted classifier cut point. A rising loss rate against a steady target is your trigger to inspect the deck.

What does the gap to target mean?

It is your loss rate minus the acceptable ceiling. A positive gap means you are over target and losing too much; the example's loss of 10.59% against a 12% target gives a 1.41-point margin still inside spec.

Does screening loss equal lost revenue?

Not entirely. Oversize that can be re-crushed or re-milled is recoverable; only true fines or unusable rejects are real material loss. Split the rejects before costing them.

Industrial Minerals & Powder Processing calculator

Screening Loss Calculator

Screening Loss is the percentage of feed material a screen or air classifier rejects as oversize plus fines rather than passing as saleable product. Quality and process engineers at sand, aggregate, talc and mineral-filler plants track it to gauge separation efficiency and product yield. Every ton rejected is feed you paid to mine, dry and convey that did not become revenue, so a creeping loss rate signals a blinded screen, worn cloth or a misadjusted classifier cut point. Comparing the loss rate to a target tells you whether the deck is performing or needs attention.

What this calculator does

Calculate the percentage of mineral feed lost as oversize rejects or undersize fines during vibrating screen, trommel, or air classifier operations.
Use it when a process engineer or quality manager needs to quantify screening losses, track reject rates over time, or justify screen media replacement, classifier tuning, or circuit redesign.
It expresses rejected material as a percentage of total feed, then compares that loss rate to your maximum acceptable target.

Formula used

Screening loss rate = rejected material / total feed to screen x 100
Gap to target = screening loss rate - maximum acceptable loss target

Inputs explained

Rejected material (oversize + fines):
Total feed to screen or classifier:
Maximum acceptable loss target:

How to use the result

Use it after a screening or classifying run to judge separation efficiency and decide whether the deck needs cleaning or retensioning.
It treats all rejects equally; it does not distinguish recoverable oversize that can be re-milled from true fines waste, so the headline loss can overstate real material loss.

Current U.S. benchmarks

Steel mill PPI stands at 348.53 (BLS, May 2026), up 6.7% from a year earlier. New factory orders are up 2.3% year over year (Census).

Common questions

How do you calculate screening loss? Divide rejected material by total feed and multiply by 100. With 9 tons rejected from 85 tons of feed that is 9/85 x 100 = 10.59% screening loss.
What is a good screening loss rate? It depends on the cut and material, but for well-graded minerals 5 to 10% is typical. The example's 10.59% sits just above a 12% ceiling-no, slightly under, with a 1.41 percentage-point cushion to the 12% target.
Screening loss vs screening efficiency, what is the difference? Screening efficiency measures how well undersize passes the deck; screening loss measures how much total feed is rejected. You can have high efficiency yet high loss if the feed simply contains a lot of off-spec material.
Why is my screening loss climbing? Common causes are blinded or pegged apertures, worn or stretched screen cloth, an overloaded deck, or a drifted classifier cut point. A rising loss rate against a steady target is your trigger to inspect the deck.
What does the gap to target mean? It is your loss rate minus the acceptable ceiling. A positive gap means you are over target and losing too much; the example's loss of 10.59% against a 12% target gives a 1.41-point margin still inside spec.

Last reviewed 2026-05-12.