Screen Efficiency Calculator
Screen (screening) efficiency in this simple form is the recovery of undersize: what fraction of the fines that entered with the feed actually passed through the deck.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the total feed rate to the screen (t/h) and the percentage of that feed that is true undersize (from a sieve/screen analysis).
- Enter the measured undersize (passing) product rate in t/h; optionally enter the undersize fraction of that stream if it is not a clean cut (defaults to 100%).
- Read the screen efficiency as undersize recovery, plus the tonnes of fines lost to the oversize stream.
How it works
Screen (screening) efficiency in this simple form is the recovery of undersize: what fraction of the fines that entered with the feed actually passed through the deck. The tool computes undersize in feed = feed rate × undersize%, and undersize recovered = product rate × product undersize%, then Efficiency = (undersize recovered ÷ undersize in feed) × 100.
Working in tonnes per hour keeps the mass balance explicit and lets the tool also report the fines that were lost to the oversize stream (undersize in feed minus undersize recovered). This is a first-pass performance indicator: it assumes reliable sampling and does not model blinding, moisture, near-size material, deck wear or oversize contamination of the undersize, so it should be treated as an estimate.
Worked example
Vibrating screen on a crushing plant. A screen is fed at 250 t/h and a sieve analysis shows 40% of that feed is undersize (should pass the deck). The undersize stream leaving the screen measures 88 t/h and is essentially clean (100% undersize). Undersize in feed = 250 × 40% = 100 t/h. Undersize recovered = 88 × 100% = 88 t/h. Screen efficiency = 88 ÷ 100 × 100 = 88.00%, with 12.00 t/h of fines lost into the oversize.
Common mistakes
- Confusing feed rate with undersize tonnage — the undersize% must come from a sieve analysis of the feed, not the whole feed mass.
- Assuming the undersize product is a perfectly clean cut; if oversize slips through, lower the product undersize fraction below 100% so the recovery is not overstated.
- Reporting more undersize recovered than was present in the feed, which signals a sampling or units error rather than a real efficiency above 100%.
Frequently asked questions
Which definition of screen efficiency does this use?
It uses the common undersize-recovery form: efficiency = (mass of undersize in the passing product ÷ mass of undersize in the feed) × 100. This is one of several plant conventions; some sites also weight in oversize-removal efficiency, so always match the definition your metallurgist or plant standard uses.
Why is my efficiency below 100%?
Real screens never recover all the fines: near-size particles, high bed depth, blinded apertures, moisture and short residence time all leave undersize in the oversize stream. The tonnes-lost figure shows exactly how much fines is being carried over.
Can I use this for aggregate/quarry screens as well as mineral processing?
Yes — the mass-balance logic is the same for any sizing screen. It is an estimate for performance monitoring, not a substitute for full screen sizing, deck selection or vendor testwork.
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