Can ShipStation automatically pick the right box?

On its own, ShipStation uses a default package or manual box selection. ShipExtension adds automated box selection: it evaluates each order's real item dimensions in 3D, chooses the smallest box the items actually fit into, and writes the weight and dimensions back to the order.

How does box selection work in ShipStation with ShipExtension?

For every order, ShipExtension expands kits into their component items, runs a true 3D fit against your box catalog, and assigns the optimal box. Matched orders get updated package, weight, and dimension values automatically — the rest of your ShipStation setup stays exactly as you configured it.

Does box optimization reduce dimensional weight charges?

Yes. Choosing the smallest box that genuinely fits lowers the billed dimensional weight and can move orders into cheaper rate tiers, which is where most of the savings on lightweight or oddly shaped orders come from.

Does it handle kits, bundles, and multi-item orders?

It does. Kits and bundles expand into the items that actually ship, so the packer sizes the box to the real contents instead of guessing. Multi-item orders are fit together rather than boxed one item at a time.

Will it change my existing ShipStation orders?

It only updates the package, weight, and dimensions on the orders it matches. It never touches your stores, carriers, or other order data, and you stay in control of which orders it applies to.

Box Optimization

The missing feature from ShipStation: automated box sizes

ShipStation doesn't calculate box sizes for multi-item orders. We do. Our 3D algorithms analyze every order and automatically select the optimal box from your inventory, then update ShipStation with the correct dimensions. Right-sizing every box also feeds cheaper rate shopping and can run automatically as part of your automation rules.

3D bin-packing algorithms for multi-item orders
Respects each box's weight limit
Updates ShipStation package dimensions automatically

Get setup help View Pricing

12" × 8" × 6"

Medium Box

How It Works

From order data to a proposed carton you can inspect

Order comes in

ShipStation receives an order with multiple items of various sizes and weights.

3D analysis

Our algorithms calculate the optimal arrangement and select the smallest box that fits.

Auto-update

Package dimensions are updated in ShipStation automatically. Ready for shipping.

Benefits

Right-sized packaging pays for itself

Lower shipping costs: Stop paying for air. Right-sized boxes mean lower dimensional weight charges and reduced carrier costs.
Faster fulfillment: No more guessing games. Pickers know exactly which box to grab for each order, speeding up the pack station.

Doing it in ShipStation vs ShipExtension

Choosing a box for a multi-item order

ShipStation

Set one default package, or pick a box by hand for every order

ShipExtension

3D-fit each order automatically, then write the right box, weight, and dimensions back to ShipStation

The right box on every order — automatically

FAQ

ShipStation box selection FAQ

Can ShipStation automatically pick the right box?: On its own, ShipStation uses a default package or manual box selection. ShipExtension adds automated box selection: it evaluates each order's real item dimensions in 3D, chooses the smallest box the items actually fit into, and writes the weight and dimensions back to the order.
How does box selection work in ShipStation with ShipExtension?: For every order, ShipExtension expands kits into their component items, runs a true 3D fit against your box catalog, and assigns the optimal box. Matched orders get updated package, weight, and dimension values automatically — the rest of your ShipStation setup stays exactly as you configured it.
Does box optimization reduce dimensional weight charges?: Yes. Choosing the smallest box that genuinely fits lowers the billed dimensional weight and can move orders into cheaper rate tiers, which is where most of the savings on lightweight or oddly shaped orders come from.
Does it handle kits, bundles, and multi-item orders?: It does. Kits and bundles expand into the items that actually ship, so the packer sizes the box to the real contents instead of guessing. Multi-item orders are fit together rather than boxed one item at a time.
Will it change my existing ShipStation orders?: It only updates the package, weight, and dimensions on the orders it matches. It never touches your stores, carriers, or other order data, and you stay in control of which orders it applies to.

Last reviewed July 17, 2026. ShipStation compares shipping services but does not compare package types; capabilities and pricing cited from ShipStation's help center and pricing page as of July 2026.

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Your first workflow

Technical details

The recurring task: Staff choose cartons manually for mixed-item orders. ShipExtension calculates packaging from item quantities and the configured product and box data.
Representative input and result: A mixed-SKU order and a box catalog can produce a proposed box or multi-package plan. Verify a representative calculation on a walkthrough before applying it.
Information needed: Measured product length, width, height and weight, units, quantities, available carton dimensions and weight limits. Import products and check local overrides.
Verification and limitations: The rule Dry Run currently describes automatic carton calculation rather than showing a complete carton result. Use assisted setup to inspect the existing packaging calculation output. Missing-data behavior varies by calculation path: some skip or flag products; the legacy calculator can estimate. Do not rely on an unmeasured item.
ShipStation API scope: Order retrieval uses V1 credentials. V2 credentials are needed for V2 shipment and multi-package operations. Confirm the selected write path during setup.
Subscription and setup: Automate: $179/month for up to 2,000 orders. Optimize: $499/month for up to 10,000 orders. Packing slips are a separate add-on. Initial setup help is available; custom implementation scope is confirmed separately.

Total processing includes fetching orders and any API operations. Time varies with batch size, actions and API pacing; no fixed completion time is guaranteed.

Get help configuring this workflow