Convert TMW (Theoretical Nominal Weight) To All Billing Methods

Theoretical Minimum Weight refers to billing weight calculated by the length, width, and density factor of the gauge (per square foot).  In other words, coil length times width times density factor of gauge ordered.  The density factor is 40.80 lbs. per square foot multiplied by the decimal tolerance.  Refer to “Steel Buyers Basics” for more on this.

Converting TMW to Actual Weight

If you are being quoted on a TMW and you want to convert to “Actual Weight” you would then take your TMW decimal (determined by your desired min. decimal tolerance multiplied by 40.80)  and divide by the average physical decimal thickness (acquired by taking micrometer readings) multiplied by the TMW price.

In short:

  •  TMW decimal ÷ Average Decimal X  TMW price = Actual price.

Converting TMW to Theoretical Nominal Weight

Theoretical Nominal Weight is sometimes referred to as book weight and is based on the nominal decimal, and the weight is calculated using the nominal steel density factor.  The density factor is 41.82 lbs. per square foot multiplied by the decimal tolerance. If you wish to convert TMW to TNW, you would take the TMW decimal and divide by the theoretical nominal decimal and then multiply by .9756.  .9756 is the difference between 40.80 lbs/per square foot (actual weight) and 41.82 lbs/per square foot (nominal weight).

In short:

  •   TMW decimal ÷ Theoretical Nominal Decimal X .9756 X TMW Price = Nominal Price.

Converting TMW to Linear Footage

When converting a Theoretical minimum weight price to linear footage price, you will simply multiply the TMW decimal by 40.80 times your price per pound, times the width of the coil in feet and that will give you the price per linear foot.


           .0356 (min decimal) x 40.80 lbs./sq. ft. = 1.45248 lbs./sq. ft.    

           1.45248 lbs./sq. ft. x $0.38 (price per lb.) = $0.55/per sq ft.

           $0.55/per sq. ft. x 4ft wide = $2.20 per linear ft

           $2.20 per linear ft x 2000 ft = $4400.00

 In short:

  •  TMW decimal X 40.80 X Price Per Pound X Width of Coil in Feet = Price per Linear Foot.

Converting TMW to Price Per Square Foot

  •  TMW Price per Pound X 40.80 X TMW decimal = Price Per Square Foot.

Converting TMW to Price Per Sheet

  • TMW Price per Pound X 40.80 X TMW Decimal X Square Footage of Sheet = Price per sheet (or price per piece).