There are several factors to consider with the hole size needed for a bulkhead. The information below is considered "general" guidelines for the most popular types of bulkheads. (For example they may not apply to schedule 80 bulkheads).
| Bulkhead Size | Recommended Hole Sizes | |
| 3/4 inch | 1 1/2 inches | 35 to 40 mm |
| 3/4 inch thick wall | 1 3/4 inches | 45 mm |
| 1 inch | 1 3/4 inches | 45 mm |
| 1 1/4 inch | 2.0 inches | 50 mm |
| 1 1/2 inch | 2 1/2 inches | 60 to 65 mm |
Be sure to check with your supplier before ordering, and be sure to have bulkheads in hand before having a tank custom drilled!!
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| 3/4 inch bulkhead | 1.0 inch bulkhead | 1 1/2 inch bulkhead |
