Connections Confirmed by DEWALT
The official DCS781 page says the saw is compatible with standard 1-7/8 and 2-1/2 in. wet/dry vacuums through the included adapter. That confirms a complete saw–adapter–vacuum solution, but it does not publish the bare saw-duct diameter.
| Vacuum size | Connection part | Status |
|---|---|---|
| 1-7/8" | Included wet/dry-vac adapter | Confirmed by DEWALT |
| 2-1/2" | Included wet/dry-vac adapter | Confirmed by DEWALT |
| Other size | Separately sized reducer | Not verified |
Check the Included Adapter
Before ordering another part, confirm that the DEWALT adapter is present in the package. This is especially important for a used, refurbished or open-box saw. Inspect both ends as well: cracks, deformation or compacted dust must not prevent proper engagement.
What If Your Hose Uses Another Size?
Do not turn the documented 1-7/8 or 2-1/2 in. compatibility into a universal-fit claim. For a 1-1/4 in., 1-1/2 in. or metric hose, measure the cuff ID and OD, identify which side inserts into the other, and select a reducer with adequate engagement depth and sealing.
Frequently Asked Questions
Which vacuum sizes are documented for the DCS781?
DEWALT lists standard 1-7/8 and 2-1/2 in. wet/dry vacuums with the included adapter.
Do I need to buy a separate adapter?
Not for the two documented sizes when the included adapter is present and undamaged.
Is a 1-1/4 in. hose confirmed?
Not by the reviewed DCS781 product page. Measure and verify a suitable reducer instead of assuming fit.
Technical Source
The 1-7/8 and 2-1/2 in. compatibility statements come from the official DEWALT DCS781 product page. DEWALT DCS781.
Remove the battery before checking the duct or adapter. Keep the hose clear of the blade path, workpiece and sliding mechanisms.