How to Test the Actual Capacity of a USB Flash Drive Using Free Software?

Why do some 64GB USB Flash Drives cost 25 yuan while others are priced at 15 yuan? Beware—you might be dealing with a “capacity-expanded drive.” I’m Mona from Shenzhen YOUSAN Factory. Today, I’m going to burn my bridges and expose the industry’s biggest dark secret, while walking you through using H2testw—a free software that leaves no counterfeit product untested.

1. What is an “expansion drive”?

What you think of as “fake goods”: Rough casing, no response when plugged in.
No, today’s “capacity-expanded drives” are highly sophisticated. They’re more cunning than you imagine.
When you plug a USB drive labeled as 64GB into your computer, Windows will tell you: “Available space: 62.5GB.” You can even copy files onto it, and the progress bar appears normal. Everything seems perfect.
The black tech behind it:
Small workshops or unregulated factories recycle discarded 4GB chips. Using mass-production tools, they modify the controller parameters to trick the computer system into displaying 64GB.
It’s like: a bucket that only holds 4 liters of water gets slapped with a “64-liter” label and sold to you at the price of 64 liters.

2. What Happens When Using Expansion Drives?

Many buyers opt for these drives to save money, only to get severely reprimanded by their bosses. Expansion drives have a critical flaw: Loop Write.

1. First 4GB of data: Writes normally and files open.
2. Data exceeding 4GB: The computer displays “Write successful,” but since physical space is exhausted, new data overwrites old data or vanishes entirely.
3. Result: Your client receives the USB drive, copies photos and contracts, then opens them at home—file names remain, but contents display as gibberish or fail to open. All data becomes unusable.

3. How to test the actual capacity using H2testw?

When faced with this situation, don’t take the vendor’s word for it, and don’t rely on your computer’s displayed properties. To determine the truth, you only need one free software tool: H2testw. It is the global standard for verifying actual storage capacity in the industry.
Step-by-Step Guide (Mona’s Step-by-Step Tutorial):

4. YOUSAN Professional USB Drive Manufacturer’s Commitment:We Sell Reputation, Not Trash!

In Shenzhen’s electronics markets, overcapacity drives may double profits, but YOUSAN steadfastly refuses to produce them.
Every chip we use is Grade A genuine full-capacity (Samsung/SK Hynix/Micron, etc.).Before shipment, our QC assembly line conducts 100% H2testw verification. We don’t need to “steal capacity” to make money—we want your repeat orders next year.

Mona’s Advice:
No matter who you buy USB Flash drives from, send this message to your supplier before placing an order:
“Acceptance based on H2testw results. If it fails (Red bar), I will return all units and refuse payment.”
If they respond evasively, it shows they have something to hide and won’t dare take your order. If they’re an honest factory like YOUSAN, they’ll applaud you.