Tank size is about workflow
A larger tank means fewer stops to empty debris or liquid, not automatically stronger suction. A compact vacuum can be easier to carry into a vehicle, onto a workbench or around the house. Large 12- to 16-gallon machines are better suited to bigger cleanup jobs where capacity and long cords matter more than portability.
Look past peak horsepower
Peak horsepower is widely used on consumer wet/dry vacuums, but it is not operational horsepower. DEWALT explicitly notes that the rating includes laboratory motor output conditions and that motors do not operate at that peak in actual use. When comparable data are available, airflow in CFM and suction or water-lift specifications provide additional useful context.
Hose diameter changes what fits
A smaller hose is easier to maneuver and works well for dust, vehicle interiors and tight spaces. A larger hose is less likely to clog on wood chips and bulky debris. Before buying, think about what you actually vacuum most often and whether your favorite nozzles, dust separators or power-tool adapters fit the hose system.
Filtration matters
Fine dust is a different job from picking up screws or water. Match the filter and bag to the debris and follow the vacuum manufacturer's wet-pickup instructions before collecting liquid. For serious dust control, a purpose-built dust extractor can offer features such as automatic filter cleaning, tool activation and specified HEPA filtration that a basic cleanup vacuum may not.
Cordless or corded?
Cordless wins for fast cleanup and mobility, especially if you already own batteries in the same platform. Corded machines avoid battery-runtime limits and are usually the better fit for long sessions. Battery and charger inclusion also matters to real purchase price; many cordless vacuums are sold as bare tools.
Our practical sizing rule
Buy the smallest machine that comfortably handles your normal mess, not the largest tank that fits your budget. For detailing and quick cleanup, portability is king. For a general garage, a mid-size wheeled wet/dry vacuum balances storage, reach and capacity. For renovation debris and large liquid pickup, move up in tank size and prioritize a drain, sturdy wheels and a hose that will not choke on debris.
Sources & further reading
DEWALT: Wet/Dry Vacuum Range · DEWALT: Peak Horsepower Explanation