Only a legal-for-trade scale reading counts when a weight is disputed. In the United States that means NTEP certification, it is legally required for any scale used in trade, and inspectors can shut down weighing operations on the spot without it. A $60 platform from a hardware store is fine for estimating and worthless in an argument.
Two different questions
This guide answers both, because they need different equipment.
"Is the yard weighing me honestly?" You do not need a certified scale to check this. You need to know what to look for on theirs, and a rough estimate of your own.
"I am buying scrap and need to weigh it." You need NTEP certification, and it is not optional.
The second is a legal question before it is a purchasing one, so it comes first.
What legal-for-trade actually means
NTEP is the National Type Evaluation Program, administered through NIST and managed by the National Conference on Weights and Measures. It tests scales against Handbook 44 for accuracy, capacity and performance across temperature and environmental variation.
A scale that passes receives a Certificate of Conformance, which authorises its use in commercial transactions across the United States.
The rule is simple: if price is determined by weight, the scale must be certified. Scrap yards are named explicitly in that category, alongside transfer stations, delis and freight.
The enforcement is real. Inspectors look for the Certificate of Conformance, and without it they can shut down weighing operations immediately. Using a non-certified scale in trade exposes an operation to fines, failed inspections and forced shutdown.
Outside the US, OIML performs the equivalent function internationally.
The three accuracy classes
Buying the wrong class is a common and expensive mistake.
| Class | Use | Relevance to scrap |
|---|---|---|
| Class II | High precision: jewellery, laboratory, pharmaceutical | Precious metal work only |
| Class III | General purpose: grocery, shipping, industrial | Bench and small platform scales |
| Class IIIL | Larger capacity: vehicle and floor scales | Floor scales and truck scales |
For scrap, Class III covers bench work and Class IIIL covers floor and truck scales. Class II is overkill for everything except precious metals.
What certification costs
| Scale | Capacity | Typical price |
|---|---|---|
| Bench or market scale | 60 lb | around $325 |
| 4 ft by 4 ft floor scale with indicator | 5,000 lb | around $895 |
| High-precision floor scale | varies, reads to 0.1 lb | above standard floor scale |
| Truck scale | vehicle loads | site-built; specify aboveground or pit type |
A 5,000 lb floor scale at under $1,000 is the entry point for a small buying operation, and it is less than most people expect. Truck scales are a different order of investment and a construction project rather than a purchase.
Checking a scale, yours or theirs
Five things to look for. These work equally well on your own equipment and on a yard's.
The NTEP CC number. Every certified device carries one. You can verify it in the NCWM database, which is worth doing when buying used equipment.
The accuracy class, marked on the device.
The maximum number of divisions, which is the scale's precision limit. A scale rated to 5,000 lb by 1 lb has 5,000 divisions.
A visible security seal or calibration mark from an authorised service provider. This is the check that matters most in a dispute, because it shows the scale has been tested and sealed rather than merely bought.
Both parts certified. In most cases the digital indicator and the weighing base both need certification, not just one. A certified base with an uncertified readout does not qualify.
Two rules that catch people out
Only a certified technician may work on the scale. They reseal it or file the paperwork when it is put into service. A broken seal on a yard's scale is a legitimate question to ask about.
Non-certified weights can never be used to calibrate an NTEP scale. Gym weights, sandbags and improvised masses are all disqualifying. Calibration requires certified test weights, which is part of what a service contract buys.
What capacity you need
Match it to your largest single load, not your average.
Under 1,000 lb: covers household and small-business non-ferrous. Copper, brass, aluminium, boards, cores.
Up to 5,000 lb: a 4 by 4 floor scale handles pallets, drums and bulk lots. This is the standard buying-yard platform.
Vehicle loads: a truck scale, which is site infrastructure rather than equipment.
Buying above your largest load costs money; buying below it means the scale cannot do the job at all, which is worse. When in doubt, size up one tier.
When you do not need certification
Worth stating clearly, because the certification requirement gets overapplied.
Internal quality control, research and process control do not need NTEP, because weight is not determining price. A non-certified industrial or laboratory scale is fine.
Estimating your own load before selling does not need it either. A cheap platform scale gives you a number to sanity-check the yard's ticket against, which is a genuinely useful thing to have and costs very little.
What that estimate cannot do is win an argument. In a dispute, only the certified reading counts, which is why the check on the yard's seal matters more than the accuracy of your own scale.
Reading a weight ticket
Most weight disputes are not about the scale at all. They are about deductions.
Ask what was deducted and why. On a vehicle, roughly 500 lb comes off for tyres and fluids before the rate is applied, which is standard practice and applies to every route. On wire, contamination and insulation are deducted. On mixed loads, the whole lot may be graded down rather than deducted.
Confirm the grade written against each pile matches what you sorted. A mixed load is paid at the lowest grade present, so a mis-written grade costs more than a mis-read weight.
Query before you sign. After the load is tipped and mixed with other material, there is nothing left to re-weigh.
The per-ton page covers the vehicle deduction in detail and the sorting tools guide covers getting the grades right before you arrive.
Around the world
The principle is universal; the scheme is not.
OIML provides internationally recognised standards for weighing equipment, and most jurisdictions run a national verification scheme with periodic testing and sealing. The practical checks are the same everywhere: look for the seal, look for the inspection date, and ask if either is missing.
Enforcement intensity varies more than the standards do. In markets with active weights and measures inspection, a yard's scale is reliably sealed and tested. Where inspection is thin, the seller's own estimate carries more weight in practice, which makes a cheap platform scale in your own workshop more useful than it would be elsewhere.
If you are setting up to buy rather than sell, the scrap business guide covers licence costs by state and the record-keeping obligations that come with dealing.
The scale picker works out whether certification is legally required for your use, and the capacity and class that follow from it.
Questions people actually ask
What does legal-for-trade mean?
That the scale meets NTEP accuracy standards and holds a Certificate of Conformance, authorising its use in commercial transactions. If price is determined by weight, US law requires it, and scrap yards fall squarely in that category.
Do I need an NTEP scale to sell scrap?
No. You need one to buy scrap, because you are then setting price by weight. For selling, the yard's certified scale is the one that counts, and yours is only for estimating.
How do I check a yard's scale is honest?
Look for the NTEP CC number, the accuracy class, and a visible security seal with an inspection date from an authorised provider. A missing or broken seal is a reasonable question to raise before weighing.
What capacity scale do I need?
Match your largest single load rather than your average. Under 1,000 lb covers household non-ferrous; a 4 by 4 floor scale at 5,000 lb covers pallets and drums; vehicle loads need a truck scale.
How much does a legal-for-trade scale cost?
A 60 lb bench scale runs around $325 and a 4 by 4 foot 5,000 lb floor scale with indicator around $895. Truck scales are site infrastructure and priced accordingly.
Can I use a bathroom scale for scrap?
For estimating, yes, and it is worth having. For any transaction or dispute, no, because it is not certified and the reading carries no standing.
Why does the yard's weight differ from mine?
Usually deductions rather than the scale. Roughly 500 lb comes off a vehicle for tyres and fluids, and wire loads are deducted for insulation and contamination. Ask what was deducted and why before you sign.
Can I calibrate an NTEP scale myself?
No. Only a certified technician may work on it, and non-certified weights such as gym weights can never be used for calibration. Doing either invalidates the certification.
Does the indicator need certification too?
In most cases yes. Both the digital readout and the weighing base need to be NTEP certified, so a certified base paired with an uncertified indicator does not qualify.
Certification requirements described are for the United States under NTEP and NIST Handbook 44. Prices are indicative 2026 street prices and vary by supplier, capacity and freight. Requirements, inspection intervals and enforcement differ by state and by country; confirm with your local weights and measures authority before buying.
Frequently asked questions
What does legal-for-trade mean?
That the scale meets NTEP accuracy standards and holds a Certificate of Conformance, authorising its use in commercial transactions. If price is determined by weight, US law requires it, and scrap yards fall squarely in that category.
Do I need an NTEP scale to sell scrap?
No. You need one to **buy** scrap, because you are then setting price by weight. For selling, the yard's certified scale is the one that counts, and yours is only for estimating.
How do I check a yard's scale is honest?
Look for the NTEP CC number, the accuracy class, and a visible security seal with an inspection date from an authorised provider. A missing or broken seal is a reasonable question to raise before weighing.
What capacity scale do I need?
Match your largest single load rather than your average. Under 1,000 lb covers household non-ferrous; a 4 by 4 floor scale at 5,000 lb covers pallets and drums; vehicle loads need a truck scale.
How much does a legal-for-trade scale cost?
A 60 lb bench scale runs around $325 and a 4 by 4 foot 5,000 lb floor scale with indicator around $895. Truck scales are site infrastructure and priced accordingly.
Can I use a bathroom scale for scrap?
For estimating, yes, and it is worth having. For any transaction or dispute, no, because it is not certified and the reading carries no standing.
Why does the yard's weight differ from mine?
Usually deductions rather than the scale. Roughly 500 lb comes off a vehicle for tyres and fluids, and wire loads are deducted for insulation and contamination. Ask what was deducted and why before you sign.
Can I calibrate an NTEP scale myself?
No. Only a certified technician may work on it, and non-certified weights such as gym weights can never be used for calibration. Doing either invalidates the certification.
Does the indicator need certification too?
In most cases yes. Both the digital readout and the weighing base need to be NTEP certified, so a certified base paired with an uncertified indicator does not qualify.