.0236 plus .008 is considered to be 24 ga
.0236 plus .004 is considered the nominal for 24 ga
.0236 + .004 = .0276
.0276 * 41.88 lb (weight of carbon steel) per cubic ft * 40 sq ft (4’x10′ sheet) = 46.24#
Actual Weight – actual scale weight of the coil
Theoretical Nominal Weight (TNW) – weight based upon the lineal footage using nominal weight per foot.
Theoretical Minimum Weight (TMW) – weight of the coil if it was rolled exactly at the minimum thickness ordered using .2833#/in.3 as the weight of steel.
Actual vs. Nominal Weight
by Robbie Thompson
I know there is lots of confusion about actual weight versus nominal weight. Actual weight is about as straightforward as it gets. It is the actual scale weight of the coil. Put it on a scale and that is what it would weigh!
However, a 24 Gauge could range from .0236 thick all of the way to .0316 thick, according to ASTM. So what weighs more 100 lbs of .0216 or 100 lbs of .0316? Hmmm – trick question! They weigh the same, of course…but one is certainly a lot shorter than the other.
Consider the difference in the footage of a 10,000 pound 24 Ga 60″ coil that was micing .0236″ and one that was .0316″. Both would weigh 10,000#, but the first coil would have 2077 lineal feet, and the other only 1551. That is a big difference! Can you imagine paying the exact same actual weight price for each coil, but one making 526 FEWER feet of ductwork??!! I know a contractor would lose money with this .0316 heavy coil, even though it is still technically 24 Ga according to ASTM.
So the nominal weight was a way to come up with an industry standard methodology for guaranteeing the yield (or lineal footage) of a particular coil. It really has nothing at all to do with how much the coil weighs. It is an industry-standard weight that is based on a coil’s lineal footage.
The nominal weight (also referred to as theoretical weight) for each gauge uses the midpoint of that gauge’s ASTM range to calculate what is called the nominal weight per foot. Since 24 Ga has an ASTM range of .0236 to .0316, the midpoint is .0276. And since ALL steel weighs approximately 41.88 lbs per cubic foot, the nominal weight of 24 Ga 60″ wide material is .0276 * 41.88 * 5’…or 5.78 lbs. per foot.
Again, the nominal weight is a way for a contractor to guarantee what his\her cost per foot of a coil will be. When you’re making ductwork that is all that matters.
That is why if we were to sell a coil using nominal weight, we would calculate the weight using the LnFt of the coil and multiplying it by the nominal weight per foot of that particular gauge.