The most frequent question we receive in regards to scales is, “What is a trade
legal scale?” We spoke to Michael Hamer at A&D Scales to find the answer,
which as it turns out, is not always easy to define. For starters, regulations differ
from state to state. However, by providing some general guidelines, we hope to
give some clarity.

Trade Legal Scales begin with the National Type Evaluation Process (NTEP). The
name really does not explain what they do or how it relates to your scale. This
is a process that each scale must go through to become “legal for trade”. To
do this, each manufacturer must submit a scale for testing to a qualified NTEP
lab. That scale is then subjected to a battery of tests that check for stability and
accuracy across a range of temperatures, humidity and outside interferences
such as static and EMF. If all goes well, the scale is passed and given a
Certificate of Conformance.

You can identify your scale as NTEP approved or “legal for trade”, by looking at
the serial number label. It will have several identifiers on the label. First, it must
have the Certificate of Conformance Number or C of C as it is abbreviated on
most scales. It also must contain the class rating for the scale. This is usually
class 2 or class 3 and is denoted by a roman numeral inside an oval. There are
other markings, but these two are the most prominent. If anyone questions the
NTEP approval of your scale, these markings will prove your case.

The problems begin when you consider weighing regulations, which differ between
states. Some states follow the NTEP rules to the letter, some have exceptions or
addendums to the NTEP rules, and a few states do not follow NTEP regulations at
all. You should contact your local office of weights and measures to check.

Another aspect to consider when dealing with scales is the calibration of a scale.

NTEP approval does not mean that the scale shows up calibrated correctly and
ready for your use right out of the box. There are many outside factors that affect
calibration. For examples, altitude greatly effects weighing. A scale calibrated at
sea level will not be accurate in Denver at an altitude of one mile. Another
outside variable is your proximity to the equator due to a difference in
gravitational acceleration. Keep these factors in mind and know that a
scale may need adjustments upon arrival.

Hopefully, this has cleared up most of your questions about trade legal scales.

For more on these and other scales available, visit

*One way to identify your scale as "trade legal" is by looking at the serial number label.