How do you calculate supplier grade variance?

Subtract the lowest reading from the highest to get the spread, then compare the midpoint of the two to your nominal target. With readings of 8 and 12 against a target of 10, the spread is 4 and the midpoint sits right on target.

What is a good supplier grade variance?

A tight spread close to zero with a midpoint near your contracted grade is ideal. The acceptable band depends on the grade and your downstream tolerance, but a spread that swamps your processing margin is a red flag regardless of the average.

Why does midpoint drift matter if the average is on target?

Drift and spread are different problems. A supplier can hit the midpoint while swinging wildly load to load, which still forces over-testing and segregation. You want both a centered midpoint and a narrow spread.

Spread vs delta to target, what is the difference?

Spread is the high-minus-low range, a measure of consistency. Delta to target is how far the center of the readings sits from your contracted grade, a measure of bias. A good supplier minimizes both.

Can two readings really characterize a supplier?

They give a useful first cut on range and center, but two points cannot show the shape of the distribution. Use this as a screening tool, then sample more loads before any contractual penalty.

How do I use this in a scorecard?

Track spread and delta to target per supplier over time. A vendor whose spread tightens and whose midpoint stays centered is trending the right way; widening spread signals a feedstock or sorting problem at their end.

Metal Recycling, Scrap Processing & Salvage calculator

Supplier grade variance Calculator

Supplier grade variance measures how widely a vendor's delivered scrap grade swings between loads and how far the center of that swing sits from the grade you contracted for. Buyers and quality engineers at recyclers track it because inconsistent grade is what wrecks downstream yield planning, even when the average looks acceptable on paper. A supplier whose copper assays bounce from spec to half-spec forces you to over-test, over-segregate, and discount, all of which erode the margin on every load. Quantifying the spread and the drift from nominal turns a vague feeling that a vendor is unreliable into a number you can put in a corrective-action conversation.

What this calculator does

Estimate supplier grade variance for metal recycling, scrap processing and salvage using production-ready inputs so teams can compare measurements against the expected process or specification window.
Use it when supplier grade variance in metal recycling, scrap processing and salvage is being audited or compared against a control chart.
It computes the range between the highest and lowest assayed grade readings and the delta between the midpoint of those readings and your nominal contracted grade.

Formula used

Supplier grade variance range = highest supplier grade variance reading - lowest supplier grade variance reading
Supplier grade variance delta to target = midpoint - nominal supplier grade variance target

Inputs explained

Highest assayed grade reading across loads:
Lowest assayed grade reading across loads:
Nominal contracted grade target:

How to use the result

Use it during supplier scorecarding, contract renewals, or when a string of off-spec loads makes you question whether a vendor's grade is drifting or just noisy.
With only a high and a low reading it captures spread and center, not the full distribution; a single outlier load can dominate the range, so back it with more sampling before penalizing a supplier.

Current U.S. benchmarks

The producer price index for steel mill products stands at 348.53 (BLS, May 2026), up 6.7% from a year earlier. Quotes priced off last quarter's material cost miss this move.
U.S. iron and steel imports ran $2.1B in May 2026 (Census International Trade). The U.S. ran a trade deficit of $0.4B in the category that month. Import volumes are the pressure gauge behind tariff and reshoring decisions.

Common questions

How do you calculate supplier grade variance? Subtract the lowest reading from the highest to get the spread, then compare the midpoint of the two to your nominal target. With readings of 8 and 12 against a target of 10, the spread is 4 and the midpoint sits right on target.
What is a good supplier grade variance? A tight spread close to zero with a midpoint near your contracted grade is ideal. The acceptable band depends on the grade and your downstream tolerance, but a spread that swamps your processing margin is a red flag regardless of the average.
Why does midpoint drift matter if the average is on target? Drift and spread are different problems. A supplier can hit the midpoint while swinging wildly load to load, which still forces over-testing and segregation. You want both a centered midpoint and a narrow spread.
Spread vs delta to target, what is the difference? Spread is the high-minus-low range, a measure of consistency. Delta to target is how far the center of the readings sits from your contracted grade, a measure of bias. A good supplier minimizes both.
Can two readings really characterize a supplier? They give a useful first cut on range and center, but two points cannot show the shape of the distribution. Use this as a screening tool, then sample more loads before any contractual penalty.

Last reviewed 2026-05-12.