https://shipmargin.net/blog/ Free calculators for shipping rates, volumetric weight, customs duty, landed cost and marketplace profit. No login, no ads, every number shows the formula and the source behind it. en https://shipmargin.net/blog/usps-dimensional-weight-divisor-change-2026/ https://shipmargin.net/blog/usps-dimensional-weight-divisor-change-2026/ On 12 July 2026 USPS moved from a 166 divisor to 139 and started rounding fractional inches up. Here is what it does to a real parcel, and how to check whether a tool has caught up. Tue, 04 Aug 2026 00:00:00 GMT weight-and-size https://shipmargin.net/blog/us-de-minimis-ended-what-it-costs-sellers/ https://shipmargin.net/blog/us-de-minimis-ended-what-it-costs-sellers/ The US suspended duty-free de minimis for all countries in August 2025 and made it permanent in 2026. Worked examples of what that does to a $12 landed cost, and what to change. Wed, 22 Jul 2026 00:00:00 GMT customs-and-duty https://shipmargin.net/blog/amazon-2026-fba-fee-changes-per-unit-cost/ https://shipmargin.net/blog/amazon-2026-fba-fee-changes-per-unit-cost/ Three price bands in January, a 3.5% surcharge in April, a Digital Services Fee expansion in March. Worked per-unit numbers, and why most FBA calculators are understating your fees. Tue, 30 Jun 2026 00:00:00 GMT marketplace-fees https://shipmargin.net/blog/what-acos-can-you-actually-afford/ https://shipmargin.net/blog/what-acos-can-you-actually-afford/ Break-even ACOS comes from your fee stack, not your campaign report. How to work it out, turn it into a bid ceiling, and why chasing a low ACOS can cost you money. Mon, 18 May 2026 00:00:00 GMT pricing-and-margin https://shipmargin.net/blog/why-your-pallet-holds-fewer-cartons/ https://shipmargin.net/blog/why-your-pallet-holds-fewer-cartons/ Dividing pallet volume by carton volume overstates what fits, often by twenty percent. How real two-block packing works, and what it changes about your freight quote. Sat, 11 Apr 2026 00:00:00 GMT freight