How to Calculate Container Load for Sinks?

How Many Sinks Fit in a Container? (And Why Most Online Calculators Are Wrong)

I still remember my first 40HC. The supplier sent me a photo of the loaded container — sinks stacked neatly, airbags inflated, everything looked perfect. Then the trucker called me from the port. "You're 4,000 pounds over the road limit." That call cost me $1,200 in special chassis rental and two days of detention.

Nobody warns you about that part.

Let me walk you through what I've learned after dozens of container shipments — mostly the hard way.

The Short Answer (Spoiler: There Isn't One)

If you Google "how many sinks per container," you'll find tables with neat numbers. 20GP: 800 pieces. 40HC: 1,600 pieces. Those numbers are garbage.

The real answer depends on three things that change with every order:

Your carton dimensions (not the sink dimensions — the carton, with foam, brackets, and sometimes a wooden frame)
The gross weight per carton (a 16-gauge commercial sink weighs way more than a 20-gauge residential one)
Whether you're shipping to a U.S. warehouse or just dropping it at a port

I've seen a 20GP swallow 220 single-bowl sinks in one shipment and barely fit 140 in another. Same container. Different packaging.

Let's Do the Math (But Keep It Simple)

Take a typical 30-inch workstation sink. The carton measures roughly 31 x 23 x 11 inches. Convert that to meters — about 0.79 x 0.58 x 0.28 — and you get roughly 0.13 cubic meters per carton.

A 40HC has about 76 cubic meters inside. In theory, that's 76 ÷ 0.13 = 584 cartons.

In reality, you lose space to pallets, gaps between boxes, and the curve of the container walls. I usually budget for 85% utilization​ — so around 496 cartons. If each carton holds one sink, that's 496 sinks.

But wait. Each carton weighs about 38 pounds (17 kg). 496 cartons × 17 kg = 8,432 kg. Well under the container's max payload of 26,300 kg. So volume is the bottleneck here.

Now try a heavy cast-iron farmhouse sink. Each carton might be 0.25 CBM and weigh 55 kg. Volume says you could fit about 260 cartons in a 40HC (65 usable CBM ÷ 0.25). But weight says 26,300 ÷ 55 = 478 cartons. So volume caps you at 260. Still fine.

But then you put that on a U.S. truck. The federal highway limit is 80,000 lbs total — truck, chassis, container, and cargo. After subtracting the weight of the tractor, chassis, and empty container, you're left with roughly 44,000 lbs (20,000 kg)​ for cargo. Your 260 cartons at 55 kg each = 14,300 kg. Safe.

Push it to a denser product — say a solid-surface integrated sink at 70 kg per carton — and suddenly 260 cartons = 18,200 kg. Still okay. But if you tried to fill the container to its ocean max of 26,300 kg, you'd blow past the road limit by over 6,000 kg. Good luck finding a chassis that can handle that without paying triple.

This is the part most Chinese factories don't tell you. They see "max payload 26,300 kg" and think they can load to that number. They can — for the ship. But once that container hits U.S. asphalt, you're in trouble.

What I Actually Do Now

I keep a simple spreadsheet. Three tabs: one for volume math, one for weight math, one for U.S. road check.

For every new SKU, I ask the factory for:

Exact outer carton dimensions (with packing materials, not just the sink itself)
Gross weight per master carton
Whether they palletize or floor-load

Then I run two calculations:

Volume-based max: Usable CBM (85% of container internal volume) ÷ carton CBM × pieces per carton
Weight-based max: Road-safe cargo weight ÷ gross weight per carton × pieces per carton

Whichever number is lower — that's your real container load. Not the one from the online calculator.

A Few Things That Have Burned Me (So You Don't Have To)

Palletized vs. floor-loaded.​ Palletizing eats about 15–20% of your container volume right off the bat. But it makes unloading faster and reduces damage. For expensive sinks, I'll take the volume hit. For cheap builder-grade models, floor-load all day.

The 20GP myth.​ Everyone assumes 40HC is always cheaper per unit. For lightweight sinks, yes. But for heavy stuff — cast iron, stone composite, big farmhouse basins — the 20GP often wins because you can't use the extra height anyway, and the road weight limit kicks in before you fill a 40-footer. I've shipped cast-iron sinks in a 20GP and gotten better per-unit freight than a 40HC would have given me.

Door clearance.​ Sounds stupid, but I once had a shipment where the cartons were too tall to slide out the container door. We had to unload half the container by hand at the warehouse. Check the door opening height (about 2.29 meters on a standard 40HC) against your pallet height plus forklift mast clearance.

The Bottom Line

There's no shortcut. Every SKU needs its own calculation. The factories that give you a quick "oh, about 400 pieces" are either guessing or quoting from a different product. Ask for the numbers. Run them yourself. And always, always check the U.S. road limit before you book