I have a vendor who has defined their shipping charges thusly: 

< 1lb. = 8.99

1.01 Pounds to 10.00 Pounds = 8.99+.50 per pound

10.01 Pounds or more = 9.99 + .40 per pound

 

I have a field called Billable weight (in Lbs.) which is essentially just the dimensional weight pre-caclulated. What formula would I use to calculate shipping charges based on my billable weight field?

Edited January 9, 20178 yr by OneStop

The formula would be almost exactly what you wrote:

Case (
BillableWeight ≤ 1 ; 8.99 ;
BillableWeight ≤ 10 ; 8.99 + 0.5 * BillableWeight ;
9.99 + 0.4 * BillableWeight
)

Note that your definition does not cover the case where the weight is exactly 1 pound.  Here we are assuming it is included in the first instance.

Worked perfectly! Thank you.