Weights, USPS, Checkout, is it my math?

[jhande]

I've recently added USPS First-Class delivery because I now offer products that weigh less than an ounce. Once packaged in a bubble wrap envelope they are still less than 13 ounces. I'm having a bugger of a time figuring the Tar Weight.

 

Examples of products -

 

Jewelry item:

Envelope = .5 ounce

Item = .3 ounce

 

So I listed Tar Weight as .03 (1oz divide by 16 = 0.0625 divide by 2 = 0.03125) (even tried .01 no difference).

For testing I left the item weight zero.

 

During checkout the USPS weight is 1x 0.1 pounds (0.1 multiply by 16 = 1.6 ounces?).

 

Now I add the weight to the product - 0.019 (.3 divide by 16 = 0.01875). Not sure if I did this correct??

So now when they add up for checkout it should equal .8 ounces.

 

But during checkout it shows 1x 0.1235 pounds.

Shouldn't it be showing 1x 0.05 pounds? (.8 divide by 16 = 0.05) ???

 

Model kit:

Package = 1 pound

Item = 1.25 pounds

 

Larger Packages - percentage increase = 80 (%)

 

Checkout shows correctly - 1x 2.25 pounds.

 

I edited the database so I could add product weights with three decimal places. Is that a problem or is there somewhere I need to edit so that USPS (module?) calculates fractions of an ounce correctly? Or maybe It's as close as I can get already?

 

My main concerns with the difference in the smaller packages not calculating correctly; is I can't hide the postage charge on the packages. I don't what customers thinking I'm cheating them if they end up paying more than what it actually cost.

 

Maybe I'm making to big of an issue out of it?

 

Any thoughts, ideas or opinions are greatly appreciated.