What Is the Magnet Test? How to Identify Scrap Metal Types
The magnet test is the fastest way to sort scrap metal and find the valuable pieces. Learn how it works, what each result means, and how to combine it with other quick tests to identify copper, aluminum, brass, stainless steel, and more.
- The magnet test sorts metal into two groups: ferrous (magnetic, contains iron, lower value) and non-ferrous (not magnetic, no iron, higher value).
- Non-ferrous metals like copper and brass sell for 25 to 100 times more per pound than steel.
- A single magnet and 30 seconds of sorting can be the difference between getting $0.06/lb and $4.00/lb for the same piece of metal.
- How the Magnet Test Works
- Why It Matters for Scrap Value
- Ferrous Metals: What Sticks
- Non-Ferrous Metals: What Doesn't Stick
- The Stainless Steel Exception
- Beyond the Magnet: Four More Quick Tests
- Real-World Sorting Strategy
- Choosing the Right Magnet
- Common Mistakes
- Common Items and What the Magnet Reveals
- When the Magnet Test Fails
- Frequently Asked Questions
The magnet test is the first thing every scrapper learns, and the one test that experienced scrappers use dozens of times a day. It takes less than a second, costs nothing, and tells you more about a piece of metal’s value than any other single test.
All you need is a magnet. Hold it against the metal. If it sticks, you’re looking at a ferrous metal (steel or iron). If it doesn’t stick, you’ve got a non-ferrous metal — and that’s where the real money is. Scrap yards in every major city rely on this test, from Houston to Los Angeles to Chicago.
How the Magnet Test Works
Every metal has a molecular structure that determines whether it responds to a magnetic field. Iron atoms naturally align into magnetic domains, which is why iron-based metals attract magnets. Metals without iron — copper, aluminum, brass, zinc, lead — have molecular structures that don’t respond to magnetism.
The test is binary: stick or no stick. That simplicity is what makes it so powerful. You don’t need training, equipment, or experience. You need a magnet and a piece of metal.
How strong does the magnet need to be?
Any magnet works — a refrigerator magnet, a magnetic phone mount, even the magnetic strip on a name badge. But a small neodymium (rare earth) magnet is ideal. They're strong enough to detect weakly magnetic metals like 400-series stainless steel that a fridge magnet would miss. You can buy one at any hardware store for a few dollars.
Why It Matters for Scrap Value
The magnet test matters because it draws a clear line between low-value and high-value scrap — a distinction that underpins the ISRI scrap metal classification system used by yards nationwide. Non-ferrous metals are worth dramatically more per pound than ferrous metals.
| Metal | Magnetic? | Typical Price Per Pound | Where You’ll Find It |
|---|---|---|---|
| Steel | Yes | $0.04 — $0.08 | Car bodies, appliances, structural beams |
| Cast Iron | Yes | $0.05 — $0.10 | Engine blocks, pipes, radiators, skillets |
| Copper (#1 Bare Bright) | No | $3.50 — $4.30 | Wiring, plumbing pipes, AC coils |
| Copper (#2 Mixed) | No | $2.80 — $3.50 | Insulated wire, fittings, connectors |
| Aluminum | No | $0.35 — $0.85 | Cans, window frames, siding, wheels |
| Brass | No | $1.60 — $2.50 | Faucets, valves, keys, shell casings |
| Stainless Steel | Depends | $0.25 — $0.55 | Sinks, cookware, medical equipment |
| Lead | No | $0.30 — $0.55 | Wheel weights, old pipes, fishing sinkers |
The math in practice
Say you have a pile of mixed metal from a garage cleanout. If you throw it all in one truck and take it to a yard unsorted, you'll get the steel rate for the entire load — maybe $0.06/lb. But if you spend 15 minutes with a magnet and separate the copper pipe, brass fittings, and aluminum from the steel, that same pile might net you 5 to 10 times more.
Use our scrap value calculator to estimate what your sorted metals are worth at today's prices.
Ferrous Metals: What Sticks
When the magnet grabs on, you’re dealing with a ferrous metal. “Ferrous” comes from the Latin ferrum (iron) — these metals all contain iron as a primary element.
Steel
Steel is by far the most common ferrous scrap. It’s an alloy of iron and carbon, and it shows up everywhere:
- Structural steel — I-beams, rebar, angle iron from construction and demolition
- Sheet steel — car bodies, appliance shells (washers, dryers, dishwashers), filing cabinets
- Steel pipe and tubing — plumbing, fencing, exhaust systems
- Tin cans — actually steel with a thin tin plating (the magnet will still stick)
Steel pays the lowest per pound of any common scrap metal, but it makes up for it in volume. A single appliance or car body can weigh hundreds of pounds.
Cast Iron
Cast iron is heavier and more brittle than steel, with a rough, grainy surface. You’ll find it in:
- Engine blocks (older vehicles and equipment)
- Cast iron pipes (homes built before the 1970s)
- Radiators (both home heating and older vehicle radiators)
- Cookware (skillets, Dutch ovens)
- Manhole covers, fire hydrants, and garden furniture
Cast iron typically pays slightly more per pound than steel because it has a higher iron content and is easier for foundries to reprocess.
How to tell steel from cast iron
Both are magnetic, so the magnet won't help here. Instead: cast iron is heavier for its size, has a rough/textured surface, and will break rather than bend. Steel is smoother, lighter gauge, and flexible. If you hit a piece with a hammer and it shatters, it's cast iron.
Non-Ferrous Metals: What Doesn’t Stick
When the magnet slides off, you’ve found the valuable stuff. Non-ferrous metals don’t contain iron, which is what makes them non-magnetic — and what makes them worth 10 to 100 times more per pound.
Copper
Copper is the king of common scrap metals. It’s easy to identify by its distinctive reddish-orange color (or green patina on weathered pieces). If you have copper to sell, check out copper recycling in Houston or find copper recycling near you. You’ll find it in:
- Electrical wiring — the single most common source. Romex house wire, extension cords, appliance power cords
- Plumbing pipe — copper pipes and fittings in homes built before the 1990s
- AC and refrigeration coils — the coils inside air conditioners, refrigerators, and heat pumps
- Transformers and electric motors — copper windings inside
Copper is graded by cleanliness, which dramatically affects price:
| Grade | Description | Typical Price |
|---|---|---|
| #1 Bare Bright | Clean, uncoated, unsoldered copper wire (14 gauge+) | $3.50 — $4.30/lb |
| #1 Copper | Clean pipe, bus bar, clippings — no solder, paint, or fittings | $3.30 — $4.00/lb |
| #2 Copper | Copper with solder, paint, or light contamination | $2.80 — $3.50/lb |
| Insulated Wire | Copper wire still in its plastic insulation | $0.80 — $2.50/lb |
Is it worth stripping copper wire?
Sometimes. Thick wire (10 gauge and above) is worth stripping — the copper recovery rate is high enough to justify the time. Thin wire like telephone or ethernet cable usually isn't. See our detailed copper wire stripping guide for the full breakdown.
Aluminum
Aluminum is silver-gray and surprisingly lightweight — noticeably lighter than any other common metal for its size. Yards across the country buy aluminum — see aluminum recycling in Chicago for an example of local pricing. Pick up two similar-sized pieces of unknown metal; if one feels strikingly light, it’s almost certainly aluminum.
Common sources:
- Beverage cans — the most recognized aluminum scrap, but low value per can (about $0.02 each)
- Window and door frames — extruded aluminum from construction
- Siding and gutters — common on homes built in the 1960s—1980s
- Wheels and rims — aluminum alloy wheels from cars and trucks
- Lawn furniture, ladders, and screen doors
- Engine parts — aluminum heads, transmission housings, radiators (modern vehicles)
Aluminum comes in several grades. Cast aluminum (engine blocks, cookware) pays less than sheet/extruded aluminum (siding, frames) because it contains more alloy impurities.
Brass
Brass is a copper-zinc alloy with a distinctive yellow-gold color. It’s heavier than aluminum but lighter than steel for the same size. Common sources:
- Plumbing fixtures — faucets, valves, pipe fittings, shut-offs
- Door hardware — knobs, hinges, locks, kick plates
- Keys — most standard house and padlock keys are brass
- Shell casings — spent ammunition brass (popular scrap item)
- Musical instruments — trumpets, trombones, French horns
- Decorative items — lamps, bookends, fireplace hardware
Watch out for brass-plated steel
Some hardware and decorative items are steel with a thin brass coating. They look like brass but are worthless at brass prices. The magnet test catches this instantly — if the magnet sticks, it's brass-plated steel, not solid brass. Always test before you assume.
Lead
Lead is very heavy, soft, and dark gray. You can scratch it with a fingernail and it leaves a gray streak on paper. Common sources:
- Wheel weights (older styles — many newer ones are zinc or steel)
- Old pipes (homes built before 1950)
- Fishing sinkers and dive weights
- Car and marine batteries (these are typically sold as whole units, not by the pound)
- Flashing and roofing (older buildings)
Lead pays moderately well and is easy to accumulate from auto shops and plumbing jobs.
Zinc and Nickel
Less common as standalone scrap, but worth knowing:
- Zinc — Die-cast parts (cabinet hardware, toy cars, carburetor bodies), newer wheel weights, galvanized coatings. Pays $0.40—$0.60/lb.
- Nickel — Uncommon as pure scrap. Most nickel scrap comes from nickel alloys (Monel, Inconel) found in industrial and marine applications. Pays well when you find it.
The Stainless Steel Exception
Stainless steel is the one metal that breaks the simple “magnet sticks = cheap, doesn’t stick = valuable” rule. Depending on its grade, stainless can be magnetic or non-magnetic:
| Stainless Grade | Magnetic? | Common Uses | Notes |
|---|---|---|---|
| 300 series (304, 316) | No | Kitchen sinks, cookware, food processing equipment, medical instruments | Most common. The magnet slides right off. |
| 400 series (410, 430) | Yes | Some appliances, automotive trim, industrial equipment | Magnet sticks, but not as strongly as carbon steel. |
How to identify stainless when the magnet doesn’t stick:
Stainless looks like regular steel — silver-gray, heavy, smooth — but the magnet fails. The giveaway is the combination of steel-like appearance + non-magnetic + relatively heavy weight. If it looks like steel but the magnet says no, it’s almost certainly 300-series stainless.
Stainless pays $0.25—$0.55/lb — far more than regular steel ($0.04—$0.08/lb), so misidentifying stainless as steel is one of the most common money-losing mistakes in scrap sorting.
The "too heavy for aluminum" test
If a non-magnetic metal is too heavy to be aluminum but has no copper or brass color, it's almost always stainless steel. Aluminum is strikingly light — about one-third the weight of steel. Stainless feels just as heavy as regular steel. That weight difference in your hand is an instant identifier.
Beyond the Magnet: Four More Quick Tests
The magnet test is your starting point. These four additional tests help you narrow things down when you’re not sure what you’re holding.
1. The Color Test
Color is the fastest visual identifier after the magnet test:
| Color | Metal |
|---|---|
| Reddish-orange (or green patina) | Copper |
| Yellow-gold | Brass |
| Silver-gray, very lightweight | Aluminum |
| Silver-gray, heavy | Stainless steel or zinc |
| Dark gray, soft, very heavy | Lead |
| Dark gray/black, hard | Steel or cast iron |
2. The Weight Test
Pick up two similar-sized pieces. Relative weight is a powerful identifier:
- Strikingly light — Aluminum (about 1/3 the weight of steel)
- Medium weight — Brass, copper (copper is slightly heavier)
- Heavy — Steel, stainless steel, zinc
- Surprisingly heavy for its size — Lead (about 1.5x heavier than steel)
3. The Spark Test
If you have a bench grinder or angle grinder, touching metal to the wheel produces characteristic sparks:
- Long white sparks with branches — Mild steel
- Short bright sparks, heavy branching — High-carbon steel
- Short red/orange sparks — Cast iron
- Very few sparks, short — Stainless steel
- No sparks — Non-ferrous metals (copper, aluminum, brass)
Safety note
Always wear safety glasses when spark testing. Never spark test near flammable materials or in enclosed spaces with poor ventilation.
4. The Sound Test
Tap the metal with a wrench, hammer, or another piece of metal:
- Clear, sharp ring — Steel (good steel rings like a bell)
- Dull, flat thud — Cast iron (absorbs vibration, doesn’t ring)
- Dull thud — Copper and brass
- Higher-pitched, lighter ring — Aluminum
- Very dull, almost silent — Lead (it’s too soft to ring)
Real-World Sorting Strategy
Here’s the workflow that experienced scrappers use. It takes about 15 minutes to sort a truck bed of mixed scrap and can multiply your payout several times over.
Choosing the Right Magnet
Any magnet works in a pinch, but your choice of magnet affects how effective the test is — especially with borderline metals like 400-series stainless.
Best option: Neodymium (rare earth) magnet
A small neodymium disc or block magnet (about the size of a quarter) is the scrapper’s best friend. Benefits:
- Extremely strong for its size — detects even weakly magnetic metals that a refrigerator magnet would miss
- Pocket-sized — easy to carry on every job
- Cheap — $3—$8 at any hardware store or online
- Durable — doesn’t lose strength over time under normal use
The string trick
Tie your magnet to a short piece of string or paracord. Swing it near a pile of metal — it'll snap toward anything ferrous. This is faster than hand-testing every piece individually, and it's the technique you'll see used at professional scrap yards.
Avoid ceramic and flexible magnets. Refrigerator magnets and the flat magnetic strips on name badges are too weak to reliably detect partially magnetic metals. They work for the obvious stuff (steel vs. copper), but you’ll miss edge cases.
Common Mistakes
Even experienced scrappers make these errors. Knowing them saves you money from day one.
Assuming all non-magnetic silver metal is aluminum. Stainless steel is also non-magnetic (300 series) and looks similar. The difference: stainless is much heavier. Selling stainless as aluminum means you might get $0.40/lb instead of $0.50/lb — not a huge loss. But selling it as steel because you didn’t magnet-test it costs you $0.40/lb or more.
Forgetting to test brass-plated steel. Decorative hardware, cheap faucets, and lamp parts are frequently brass-plated steel. They look like solid brass but are worthless at brass prices. One magnet test catches it every time.
Mixing grades within a metal. Sorting copper from steel is step one. But sorting #1 copper from #2 copper, or clean aluminum from dirty aluminum, is where the real money is. If you put one piece of soldered copper in your #1 bare bright pile, the whole pile drops to #2 pricing.
Throwing away “junk” without testing. Old keys, spent shell casings, broken faucets, and worn-out plumbing valves are brass. Corroded green pipes are copper. Lightweight lawn chairs are aluminum. Things people throw in the trash are often worth $1—$3/lb at a scrap yard. Find a yard in Dallas or Philadelphia to see what they’ll pay.
Not magnet-testing appliances before hauling. Some appliance components are aluminum or copper (compressors, motors, heat exchangers). Pulling these out before scrapping the steel shell adds significant value. A refrigerator compressor alone has 1—2 lbs of copper inside.
Common Items and What the Magnet Reveals
Here’s a quick-reference for common household and jobsite items you might test. This table answers the question: “I found this — is it worth anything?”
| Item | Magnet Sticks? | What It Is | Approximate Value |
|---|---|---|---|
| Old copper pipe | No | Copper (#1 or #2) | $2.80—$4.30/lb |
| Extension cord | No (copper inside) | Insulated copper wire | $0.80—$2.50/lb |
| Brass faucet | No | Brass | $1.60—$2.50/lb |
| Aluminum can | No | Aluminum | ~$0.02/can |
| Window frame (lightweight) | No | Extruded aluminum | $0.50—$0.85/lb |
| Car wheel (alloy) | No | Aluminum alloy | $0.40—$0.70/lb |
| Old keys | No | Brass | $1.60—$2.50/lb |
| Kitchen sink | No | 300-series stainless | $0.25—$0.55/lb |
| Cast iron skillet | Yes | Cast iron | $0.05—$0.10/lb |
| Steel rim | Yes | Steel | $0.04—$0.08/lb |
| Washing machine shell | Yes | Sheet steel | $0.04—$0.08/lb |
| Brass-plated door hinge | Yes | Steel (plated) | $0.04—$0.08/lb |
| Refrigerator | Yes (shell) / No (compressor) | Steel shell + copper/aluminum inside | Pull the valuable parts first |
| Catalytic converter | Depends | Specialty item — precious metals inside | $50—$800+ |
When the Magnet Test Fails
The magnet test is powerful, but it’s not perfect. Here are the situations where you need additional tests:
Plated Metals
The most common trap. Plating puts a thin layer of one metal over another:
- Brass-plated steel — Looks like brass, sticks to a magnet. Common in cheap hardware and decorative items.
- Chrome-plated steel — The shiny finish on bumpers, bathroom fixtures, and tools. Still steel underneath — the magnet confirms it.
- Nickel-plated steel — Some keys and fasteners. Sticks to a magnet.
- Copper-clad steel — Found in cheap electrical wire (especially imported). The magnet catches it — real copper won’t stick at all.
The rule: Always trust the magnet over appearances. If it sticks, the base metal is steel regardless of what the surface looks like.
Mixed-Metal Assemblies
Many items contain multiple metals bonded or fastened together:
- Electric motors — Steel housing, copper windings, aluminum end bells. Worth disassembling for the copper. See our preparing scrap metal guide for techniques.
- Radiators — Copper or aluminum fins soldered to brass or steel headers. Sold as a whole unit, graded by the dominant metal.
- Circuit boards — Contain copper, gold, tin, lead, and more. Sold as e-waste to specialized processors.
- Catalytic converters — Steel shell with precious metals inside (platinum, palladium, rhodium). The value is in the catalyst, not the shell. See our catalytic converter guide for details.
Alloys That Confuse the Test
Some alloys contain iron but not enough to trigger a strong magnetic response:
- Some tool steels — High-alloy tool steels can have a weak or inconsistent magnetic response.
- Nickel alloys (Monel, Inconel) — Used in marine and industrial applications. Can be weakly magnetic. Very valuable if you find them.
- Manganese steel — Non-magnetic despite being an iron alloy. Rare in household scrap but common in industrial wear parts.
Frequently Asked Questions
What is the magnet test for scrap metal?
The magnet test is a simple method to sort scrap metal into two groups: ferrous (magnetic, contains iron, lower value) and non-ferrous (not magnetic, higher value). Hold a magnet against the metal — if it sticks, it’s ferrous. If it doesn’t stick, it’s non-ferrous and typically worth 10 to 100 times more per pound. It’s the most fundamental technique in scrap metal sorting.
What kind of magnet should I use?
A small neodymium (rare earth) magnet is ideal — they’re strong enough to detect weakly magnetic metals like 400-series stainless steel that a refrigerator magnet would miss. You can buy one at any hardware store for $3-$8. Avoid ceramic and flexible magnets for scrap testing.
Does stainless steel stick to a magnet?
It depends on the grade. 300-series stainless (the most common, used in sinks and cookware) is non-magnetic. 400-series stainless is magnetic. This is the one metal that breaks the simple “stick = cheap, no stick = valuable” rule. If a piece looks like steel but the magnet won’t grab it, it’s almost certainly 300-series stainless — worth $0.25—$0.55/lb vs. $0.04—$0.08/lb for regular steel.
What metals are worth the most as scrap?
Non-ferrous metals are worth dramatically more. Copper (#1 bare bright) pays $3.50—$4.30/lb, brass pays $1.60—$2.50/lb, and aluminum pays $0.35—$0.85/lb. Compare that to steel at just $0.04—$0.08/lb. Check today’s scrap metal prices for current rates, or use our scrap value calculator to estimate your payout.
Can the magnet test be wrong?
The magnet test can be misleading in a few cases: brass-plated steel will stick despite looking like brass, copper-clad steel in cheap wire will also stick, and 400-series stainless steel is magnetic despite being stainless. Always combine the magnet test with visual checks for color, weight, and surface texture.
How do I sort scrap metal before going to the yard?
Start with a magnet sweep to separate ferrous from non-ferrous. Then color-sort the non-ferrous pile: copper (red/orange), aluminum (silver, lightweight), brass (yellow-gold), and stainless (silver, heavy). Finally, grade within each metal type — clean copper separate from insulated wire, for example. Our guide on preparing scrap metal covers the full process.
The magnet test is simple enough that you can teach it to a child, and powerful enough that professionals rely on it every day. It’s the single most important tool in scrap metal sorting — which is exactly why we named this site after it.
Explore more guides to deepen your scrap metal knowledge:
- How to Sell Scrap Metal — the complete beginner’s walkthrough
- Understanding Scrap Metal Prices — how commodity markets set what you earn
- Most Valuable Scrap Metals — which metals to prioritize
- Should You Strip Copper Wire? — when stripping pays off
- Scrap Metal Laws by State — what you need to know legally
- Catalytic Converter Scrap Value — pricing, legality, and where to sell
Ready to put it into practice? Find a scrap yard near you and check today’s scrap prices to see what your metals are worth. You can also browse yards in Phoenix, New York, Miami, and other major cities.
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