1,536 cubic inches ÷ 139 = 11.05, rounded up to 12 lb for UPS Daily Rates and FedEx. USPS bills actual weight because the box is not larger than 1 cubic foot.
How heavy does a 16x12x8 box need to be to avoid DIM charges?
With UPS and FedEx, anything packed under 12 lb is billed as 12 lb. Above that, you pay actual weight.