Selling through Amazon opens a huge ecommerce marketplace.

But the reason they’re so successful is the same reason they have strict packaging standards: Amazon is an efficiency beast. They need every box to sail through conveyor belts, sortation, stacking, and last mile delivery without damage or slowdowns.

That’s why Amazon requires ISTA 6 testing.

ISTA 6 simulates the journey through Amazon’s fulfillment system, from the warehouse to your customer’s doorstep.

If your boxes pass, you’ve got a smooth entry point into the Amazon fulfillment network. But failed tests risk delayed approvals, added freight costs, chargebacks, and damaged product reviews that kill sales momentum. 

This guide cuts through the complexity of ISTA 6 by answering three key questions: 

• What’s the difference between SIOC and Overbox testing? 
• Why do boxes fail these tests? 
• And most importantly—how do you design packaging that passes on the first try?

But first, let’s get clear on what exactly ISTA 6 means for your business.

What Every Seller Should Know About ISTA 6

The International Safe Transit Association (ISTA) is basically quality control for your packaging.

Amazon’s ISTA 6 protocols simulate what your package goes through in their fulfillment network—from conveyor drops to truck vibrations to stacked pallet loads. If your boxes survive the test, they’re a lot more likely to survive real-world distribution.

Passing ISTA 6 not only means fewer damaged shipments and returns, it’s the ticket to smooth onboarding with Amazon Vendor Central or Seller Fulfilled Prime. 

Which means more sales, more quickly.

SIOC vs. Overbox: How to Understand Amazon’s Two ISTA 6 Options

Amazon gives you two routes to passing ISTA 6 testing: SIOC (Ships in Own Container) or Overbox. 

This choice isn’t just technical—it affects costs, sustainability, and customer experience. Understanding the differences will save you time and help you design smarter packaging from the start.

SIOC (Ships in Own Container):

This means exactly what it sounds like. Your products can go through Amazon’s fulfillment network in nothing more than the package you ship them in.

This means lower freight costs, faster fulfillment, and less corrugated material, generally making it the more sustainable option.

Typically SIOC works well for larger, sturdier products like appliances, electronics, or bulk household goods.

Overbox: 

With overbox, Amazon puts your packaged product inside a second, outer corrugated box before shipping it to the customer.

This extra protective layer is helpful for fragile products, items that are easily scuffed, or anything else that would benefit from a little extra protection.

It’s more expensive and less sustainable, but can help delicate products pass testing—leading to fewer returns down the road.

Should You Choose SIOC or Overbox Testing?

Amazon doesn’t leave it entirely up to guesswork—they provide guidelines for which pathway applies. 

Still, manufacturers often face gray areas, especially when balancing product protection with cost and sustainability. A clear decision up front prevents wasted time testing the wrong method.

The decision typically comes down to product characteristics. Weight, fragility, and category are the biggest factors, but customer expectations around unboxing can also play a role.

• Weight and size: Larger or heavier items lean toward SIOC.
  
  
• Fragility: Delicate products often require Overbox for added protection.
  
  
• Unboxing experience: Premium or branded products may benefit from SIOC to showcase design.
  
  
• Category norms: Furniture, appliances, and bulk grocery are common SIOC candidates; glassware and personal care default to Overbox.

How to Avoid Common ISTA 6 Failure Points With Smart Packaging Design

When a package fails ISTA 6, it’s not usually due to a single catastrophic weakness. 

Instead it’s a mix of smaller issues—tape that gives out under stress, dimensions that throw off palletization, or box panels that fail under weight. But since these failure points are predictable you can head them off with smart design choices before you ever send a sample to the lab.

The most common pitfalls include:

• Box crush and panel failure under stacking loads.
  
  
• Corner and edge damage during repeated drop tests.
  
  
• Tape or glue adhesion issues that cause seams to split.
  
  
• Oversized dimensions or pallet overhang that create instability.
  
  
• Internal shifting that damages both product and packaging.
  
  

Addressing these weak spots doesn’t mean overbuilding or overspending. It means engineering with Amazon’s test conditions in mind. 

A few proven design levers make all the difference:

• Choose the right board grade and flute to handle product weight.
  
  
• Add reinforcements at corners, edges, or panels where damage is most likely.
  
  
• Dial in the fit so the product stays snug and stable in transit.
  
  
• Use strong seals like crash-lock bottoms or reinforced glue seams in high-stress areas.
  
  
• Prototype early to validate before paying for official testing.

Our in-house design team helps you design your packaging against common failure points, so your ISTA 6 testing doesn’t have to feel like a gamble. You’re more likely to pass on the first try.

Step-by-Step ISTA 6 Testing Checklist

Getting ready for ISTA 6 doesn’t have to feel overwhelming. With a clear process, you can approach testing with confidence and minimize the risk of surprises. Think of it in two stages: preparation before the test and execution during the test itself.

This framework gives your team clarity on what to gather, how to prepare prototypes, and what to expect at the lab.

Before You Test

• Collect product details: dimensions, weight, fragility.
  
  
• Decide whether SIOC or Overbox is required.
  
  
• Build and review prototypes with your packaging supplier.

During Testing

• Run preliminary drop and crush checks in-house.
  
  
• Submit packaging to an ISTA-certified lab.
  
  
• Provide a lab request form outlining your product, packaging, and chosen pathway.

Practical Tips to Pass ISTA 6 Testing Quickly—Without Overspending

Amazon compliance can feel like another mountain to climb on top of production, distribution, and retail requirements. 

The good news: smart preparation pays off quickly. By treating testing as part of your design process—not just a hurdle—you’ll save both money and momentum.

Here are a few lessons our clients wish they’d known earlier:

• Don’t over-specify board grade—extra cost doesn’t guarantee a pass.
  
  
• Prototype early and often to catch issues before the lab does.
  
  
• Work with a supplier who can iterate fast when tweaks are needed.
  
  
• View failures as data—each failed test reveals what needs to change.

We’ll work with you to prototype fast and dial in the exact specifications you need to pass testing.

Get a Packaging Partner Who Gets You Across the Finish Line

Amazon’s ISTA 6 testing may seem daunting, but it’s entirely manageable with the right approach. 

The companies that pass on the first try don’t rely on chance—they invest in smart design, clear testing pathways, and quick iterations when needed.

At Pacific Box Company, our in-house design team prototypes, tests, and refines fast. That way you get packaging that works—for Amazon and for your customers—more quickly and reliably.

If you’re ready for a packaging partner who will work right alongside you to get you across the ISTA 6 finish line, get in touch today and we’ll show you what’s possible.