How do you calculate recycling contamination rate?

Divide the weight of contaminated material by the total incoming material inspected, then multiply by 100. With 1,350 kg contaminated out of 27,000 kg inspected, that is 1,350 / 27,000 x 100 = 5%.

What is a good recycling contamination rate?

Most buyers and MRFs want bales under 3-5% by weight; curbside single-stream often runs 15-25% at intake before sortation. The 5% in this example sits right at the edge of acceptable and is 1 point over a 4% contract limit.

What does a negative gap to target mean?

The gap here is -1 point, meaning the 5% actual rate exceeds the 4% allowable by one point. A negative gap (actual above limit) signals the load is out of spec and likely to be downgraded or surcharged.

Why measure contamination by weight instead of by piece count?

Buyers pay and penalize by tonnage, so weight aligns the rate with the commercial penalty. The trade-off is that light bulky contaminants like film understate by weight, so a weight rate can look clean while still fouling optical sorters.

Does contamination rate include moisture?

It depends on your spec. Many recyclate contracts treat excess moisture as a separate deduction, so unless your inspection counts wet weight as contamination, keep moisture out of this number and track it on its own line.

How can we lower the rate before shipping?

Re-sort the worst inbound loads, reject non-conforming suppliers at the gate, and add a manual pick or eddy-current pass. Dropping the example from 5% to under 4% closes the 1-point gap and avoids a downgrade.

Circular Economy, Recycling & Remanufacturing calculator

Recycling Contamination Rate Calculator

Recycling contamination rate is the share of an incoming recyclate stream that is non-target material — wrong polymers, food residue, film, fines, or trash baled in with the good stock. MRF operators, plastics recyclers, and remanufacturers track it because contaminated bales get downgraded, rejected, or surcharged at the buyer's gate, and because high contamination jams sortation lines. Most off-take contracts and buyers set a maximum allowable contamination, often in the 3-5% range, so the number directly governs whether a load sells at grade or gets discounted. This calculator turns inspected weights into a rate and shows exactly how many points you are above or below that limit.

What this calculator does

Calculate contamination share in a recycling stream so teams can understand reject risk and downstream processing penalties.
a team needs to change supplier acceptance rules, sorting labor, or customer feedback for a inbound recycling stream
It computes contaminated material as a percentage of inspected incoming material, then compares that rate to your maximum allowable contamination threshold.

Formula used

Recycling Contamination Rate = contaminated material found ÷ incoming material inspected × 100
Recycling Contamination Rate gap to target = actual result - maximum allowable contamination rate

Inputs explained

Contaminated material found:
Incoming material inspected:
Maximum allowable contamination rate:

How to use the result

Use it on inbound load audits, supplier scorecards, and before shipping a bale to confirm it sells at grade rather than getting downgraded.
A bulk weight rate hides composition — 5% film behaves very differently from 5% wrong-color PET, so pair the rate with a contaminant breakdown before deciding on remediation.

Common questions

How do you calculate recycling contamination rate? Divide the weight of contaminated material by the total incoming material inspected, then multiply by 100. With 1,350 kg contaminated out of 27,000 kg inspected, that is 1,350 / 27,000 x 100 = 5%.
What is a good recycling contamination rate? Most buyers and MRFs want bales under 3-5% by weight; curbside single-stream often runs 15-25% at intake before sortation. The 5% in this example sits right at the edge of acceptable and is 1 point over a 4% contract limit.
What does a negative gap to target mean? The gap here is -1 point, meaning the 5% actual rate exceeds the 4% allowable by one point. A negative gap (actual above limit) signals the load is out of spec and likely to be downgraded or surcharged.
Why measure contamination by weight instead of by piece count? Buyers pay and penalize by tonnage, so weight aligns the rate with the commercial penalty. The trade-off is that light bulky contaminants like film understate by weight, so a weight rate can look clean while still fouling optical sorters.
Does contamination rate include moisture? It depends on your spec. Many recyclate contracts treat excess moisture as a separate deduction, so unless your inspection counts wet weight as contamination, keep moisture out of this number and track it on its own line.

Last reviewed 2026-05-12.