If you want to calculate freight cost from china (or any other country) to USA that includes custom broker service, you can use freightos.com create an account, enter the carton dimension and weight, you will then get live quotes!
For demostic freight cost, I’d highly recommend to use amazon partnered carrier (UPS and Fedex) when creating shipping plan, if you’d like to ship within USA, since they’ll give you really good discount, which nobody would be able to get as an individual
To calculate the shipping cost using amazon partnered carrier:
you should create a shipping plan (If you’re not over-stocked and amazon let you do so, because you may not be to create a shipping plan if you’re over the restock limit) and the very end of the shipping plan where it says ”shipping services” choose either Fedex or UPS and then scroll down and under ”shipping charges” click on ”calculate” button, amazon will then give you the shipping cost from your home or freight forwarder warehouse in the USA to fulfillment centre.
Keep in mind that in order to calculate the right shipping cost you need put your home address or freight forwarder address or 3PL that’s based in USA in the ”Ship from” Section when creating the shipping plan.
Please see the attached photo, they may help for the better understanding 🙂