JA Technology Solutions
Shipping Box Calculator
Find the optimal box size from standard carrier catalogs based on your item dimensions and weight.
Shipping Box Calculator
Enter up to 20 items with dimensions, weight, and quantity. The calculator finds the smallest standard box from UPS, FedEx, and USPS catalogs that fits everything with your specified padding allowance. See void fill percentage (color-coded), dimensional weight, and billable weight per carrier. Includes a browsable reference of all standard box sizes across all three carriers.
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Why Box Size Matters
Shipping in an oversized box means you're paying for air — literally. Carriers charge by the greater of actual weight or dimensional weight, so a box that's too large for its contents inflates your shipping cost even when the package isn't heavy. At the same time, a box that's too tight risks damage. The goal is the smallest standard box that fits your items with just enough void fill for protection.
Void Fill Guidelines
Under 20% void fill is ideal — the product fits snugly with minimal packing material. 20–40% is acceptable if items need cushioning. Over 40% means the box is too large and you should consider a smaller size or custom packaging. Every percentage point of void fill is wasted cube on the truck and added material cost.
Automating Cartonization
In high-volume fulfillment, automated cartonization selects the optimal box for each order based on the items picked. Combined with the Freight Rate Estimator and carrier APIs, this drives real-time rate shopping that picks both the best box and the cheapest carrier for every shipment.
Need automated cartonization in your warehouse? I build custom pack-and-ship integrations that select boxes, calculate rates, and print labels. Supply chain services · Ask James
All tools run entirely in your browser. Your data never leaves your machine. Need help? Ask James.