Best Pick
⚠ DIM +22 lb100% Perfect fitGRAINGER APPROVED 493T78 PK 25 Shipping Box,20x16x12 in 493T78
20″ × 16″ × 12″
+$9.99 Seller Calculated · 24 lb billed
$2.66
landed per box
$2.26 each
pack of 25 · $56.50
← NiceBoxFinder⚠ DIM +22 lb100% Perfect fit 
⚠ DIM +29 lb92% Perfect fitBuy →
⚠ DIM +37 lb85% Snug fitBuy →
⚠ DIM +27 lb93% Perfect fitBuy →
⚠ DIM +22 lb100% Perfect fitBuy →
⚠ DIM +45 lb80% Snug fitBuy →
Cheapest 20×16×12 padded mailer
Compare real eBay prices for 20×16×12 shipping boxes with DIM-weight-aware shipping estimates.
Live listings — sorted by landed cost per box
⚠ DIM +22 lb100% Perfect fitBuy →
⚠ DIM +29 lb92% Perfect fit20x16x16 Corrugated Shipping Boxes 25/pk
20″ × 16″ × 16″
+$0.00 Seller Free shipping · 31 lb billed
$3.33
landed per box
$3.20 each
pack of 25 · $80.00
⚠ DIM +37 lb85% Snug fit22x18x16 Corrugated Shipping Boxes 15/pk
22″ × 18″ × 16″
+$0.00 Seller Free shipping · 39 lb billed
$3.55
landed per box
$3.30 each
pack of 15 · $49.50
⚠ DIM +27 lb93% Perfect fitGRAINGER APPROVED 493T90 PK 15 Shipping Box,22x18x12 in 493T90
22″ × 18″ × 12″
+$9.99 Seller Calculated · 29 lb billed
$3.97
landed per box
$3.17 each
pack of 15 · $47.55
⚠ DIM +22 lb100% Perfect fit25 Boxes 20x16x12" Corrugated Shipping Boxes ECT-32 Kraft Packing Carton
20″ × 16″ × 12″
+$0.00 Seller Free shipping · 24 lb billed
$4.55
landed per box
pack of 25 · $113.75
⚠ DIM +45 lb80% Snug fit15 Pack 24x18x18 Kraft Cardboard Carton Mailer Shipping Corrugated Packing Boxes
24″ × 18″ × 18″
+$0.00 Seller Free shipping · 47 lb billed
$4.80
landed per box
$4.36 each
pack of 15 · $65.40
Showing 6 of 21 real listings. Want all of them with custom quantity and weight? Search now →
What fits in a 20×16×12 box
A 20 × 16 × 12 inch box holds 3,840 cubic inches (2.22 cu ft) of interior space, putting it in the large-category. It's a popular choice for shipping items like multiple pairs of shoes, small appliances, clothing bundles — things that fit comfortably within those dimensions while leaving room for protective padding. Large boxes at this size are usually sold in smaller bulk packs — 10 to 25 — because storage and shipping of the empty stock itself becomes a consideration.
Shipping math for this size
Shipping cost for this size depends heavily on dimensional weight. For a 20×16×12 box, UPS and FedEx Ground compute a DIM weight of 28 lbs using their 139 divisor, while USPS Ground Advantage uses a 166 divisor, giving 24 lbs. Carriers bill whichever is greater — your actual weight or the DIM weight. USPS's higher divisor makes it roughly 4 lbs cheaper than UPS/FedEx for this size when your item is light, which is why our search results factor in DIM-weight automatically instead of just showing sticker prices.
How to pick the right pack size
When buying a 20×16×12 box, the biggest cost lever isn't which retailer you pick — it's which pack size you commit to. A 100-pack typically costs 2-3× more than a 25-pack but brings the per-unit cost down by 40-60%. Our ranking is based on **landed cost per box** — the pack price plus shipping, divided by the number of boxes. A 100-pack with $10 shipping works out cheaper per box than a 25-pack with the same shipping, because the fixed cost spreads further. Every listing below links to a real product page from eBay, ULINE, or other retailers; we don't show placeholder results.
Search with your own dimensions
Pre-filled with 20×16×12. Adjust weight, quantity, or size as needed — we'll re-rank for your exact scenario.