By Saturday Gear Co. Editor · Published September 29, 2026
A shop-vac spec chart you can actually use
| Specification | What it tells you | Check alongside it |
|---|---|---|
| CFM (cubic feet per minute) | Airflow measured under the maker's stated conditions. | Hose diameter and length, filters, nozzle restrictions and whether makers measured the same way. |
| Water lift / sealed pressure | Maximum suction pressure at zero airflow. | Airflow during real use; the sealed number is not the operating condition at an open nozzle. |
| Peak horsepower | A laboratory motor-output label used on many consumer vacs. | Do not treat it as continuous operating power or a substitute for airflow and suction data. |
| Tank gallons | Drum volume and how often you may need to empty it. | Actual usable collection capacity, weight, storage space and the job's debris volume. |
These definitions come from Shop-Vac's explanation of CFM and sealed pressure and RIDGID's specification notes. Shop-Vac says hose and filter choices alter the load seen by the motor; a dirty filter can greatly reduce performance. That is why a single advertised CFM figure is a starting point rather than a guarantee at the nozzle.
How the job changes the priority
- Leaves, wood chips and general garage debris: Look at airflow, a hose wide enough to pass the debris, and a tank that is practical to empty. A narrow tool hose may clog even with an impressive motor rating.
- Car interiors and crevices: Portability, a useful narrow nozzle, hose reach and adequate suction can matter more than buying the largest drum.
- Tool-connected sawdust: Confirm hose and port compatibility, suitable filtration and whether the extractor starts with the tool. The whole collection path matters.
- Fine dust: Select a filter and collection method rated for the material. Ordinary general-debris filters are not automatically appropriate for hazardous dust. Follow the tool and material instructions.
Two real spec sheets—and why they are not a race
RIDGID lists its 6-gallon HD0600 at 64 CFM and 67 inches of lift. Festool lists the CT 26 EI HEPA extractor at a maximum 138 CFM and 96 inches of static water lift, plus tool-triggered operation and a HEPA filter. Both are manufacturer specifications. They describe very different machines with different intended workflows, accessories and measurement descriptions; the larger numbers alone do not tell you which is a better value for cleaning a car or capturing dust at a saw.
The useful comparison is between candidates that fit the same job. Confirm current model numbers, hose sizes, included filters, replacement-part availability and the measurement conditions. If one manufacturer omits CFM or lift, do not fill the blank with a guessed value.
Three buying mistakes to avoid
- Buying by peak HP: Shop-Vac says that label is a laboratory peak and does not describe normal operation.
- Comparing numbers measured differently: An airflow figure measured at one motor orifice is not necessarily the airflow delivered through another machine's long, filtered hose.
- Ignoring the filter: A clogged or unsuitable filter can erase the advantage suggested by the motor specification. Consider maintenance and replacement cost before buying.
Sources checked September 29, 2026: Shop-Vac performance definitions · RIDGID HD0600 specifications · Festool CT 26 EI HEPA specifications. Specifications can change by revision.
Editorial note: This is research-based buying guidance, not a controlled comparison or a claim that Saturday Gear Co. Editor tested the RIDGID or Festool examples. There are no affiliate checkout links on this page. The related sizing guide contains clearly identified affiliate links. Read our editorial policy and affiliate disclosure.