Pick the wrong dunnage bag size and securing performance drops sharply: too big and it will not fit the void; too small and it cannot reach the cargo on both sides after inflation — a wasted bag. The core rule for sizing is simple — match bag width to void width, and bag height to cargo height.

1. Measure the Void First, Then Choose the Bag

After loading, measure the void widths between cargo units and between cargo and container walls with a tape, plus the stacking height of the cargo. Bag width should be slightly wider than the void (inflation locks it by compression); bag height usually matches cargo height or sits slightly lower, leaving a little working room at the top.

2. Common Dunnage Bag Sizes vs. Void Ranges

Using Tezheng’s standard dunnage bag sizes as an example:

• 50×100 cm: 10–20 cm narrow voids; small items, gaps between cartons.
• 80×120 cm: 15–30 cm voids; one of the most-used general sizes.
• 90×180 cm / 100×180 cm: 20–40 cm voids; matches standard pallet cargo height.
• 100×220 cm: 25–45 cm voids; high-cube containers and extra-tall cargo.
• 120×180 cm: 30–50 cm wide voids; one bag handles it.

3. Bigger or Smaller — Which Is Safer?

When in doubt, go slightly bigger, not smaller. An oversized bag can run at slightly lower pressure and conform softly; an undersized bag must be pumped hard to “reach” both sides — risking overpressure and shortening its life. If your void falls between two sizes, take the larger one.

4. What About Irregular Voids?

For odd-shaped cargo and uneven voids, combine two bags of different sizes, or ask a dunnage bag manufacturer for custom dimensions. Tezheng supports custom width, height and material grammage across its kraft composite, PP woven and large-valve series, with standard 50×100 to 120×180 cm sizes kept in stock.