How Many Sandbags for a Basement Window?
How Many Sandbags for a Basement Window?
Basement windows are a top three cause of residential flooding. Water pools in the window well, rises above the sill, and pushes through the frame or through the glass itself if water pressure gets high enough. Protecting the window well with sandbags stops water before it reaches the glass.
Quick answer for a basement window well
The exact number of StormBag sandless sandbags you need to protect a basement window well depends on the width of the opening and the expected water height. Here are the specific counts:
Standard 32-inch basement window well
| Expected water height | Bags needed | Recommended kit |
|---|---|---|
| 4" | 4 | 10-Pack Box ($99.99) or Single-Door Kit |
| 8" | 7 | 10-Pack Box ($99.99) or Single-Door Kit |
| 12" | 10 | 10-Pack Box ($99.99) or Single-Door Kit |
| 16" | 17 | 25-Pack Box ($239.99) or Single-Door Kit |
| 24" | 24 | 25-Pack Box ($239.99) or Single-Door Kit |
Large 4-6 ft basement window well
| Expected water height | Bags needed | Recommended kit |
|---|---|---|
| 4" | 6 | 10-Pack Box ($99.99) or Double-Door Kit |
| 8" | 11 | 25-Pack Box ($239.99) or Double-Door Kit |
| 12" | 17 | 25-Pack Box ($239.99) or Double-Door Kit |
| 16" | 28 | Double-Door Kit ($109.99) × 2 or bulk order |
| 24" | 39 | Double-Door Kit ($109.99) × 2 or bulk order |
How the count is calculated
StormBag sandless sandbags measure roughly 14 inches wide and 4 inches thick when hydrated. The formula: (opening width in inches ÷ 14) × (water height in inches ÷ 4), rounded up, plus 10% overage for irregularities and a stability row on top for water heights above 12 inches. This is the same USACE-derived formula the StormBag Sandbag Calculator uses.
Deployment notes for a basement window well
Basement window wells trap water fast because they sit below grade with no drainage outlet during heavy rain. Deploy sandbags along the exterior perimeter of the window well — not inside it — so water is diverted around, not into, the well.
Get an exact count for your specific opening
The table above uses standard opening widths. If your opening is slightly different — a non-standard patio door, an oversized garage, a custom basement window — use the calculator to get the exact bag count for your measurements.
StormBag Sandbag Calculator
Enter your opening width and expected water height. Get the exact bag count and a kit recommendation.
Open the Calculator