Dust Collection Calculator
Estimate shop dust collection airflow, duct conveying velocity, equivalent duct length, static pressure loss, and collector margin for one active machine or shared branch.
Start with a common woodworking setup, then tune the CFM demand, duct path, fittings, blast gates, and collector rating to match your shop.
Required airflow
0
CFMTool demand with open gates.
Duct velocity
0
Compare with chip carrying target.
Static pressure
0.0
in. wcDuct, fittings, filter, and reserve.
Collector margin
0%
capacityAirflow and pressure capacity check.
Formula breakdown
| Tool or hood | Typical CFM range | Common port size | Design note |
|---|---|---|---|
| Table saw, enclosed cabinet | 350 to 450 CFM | 4 in port | Over-arm capture may need a second small branch. |
| Portable or contractor saw | 250 to 400 CFM | 2.5 to 4 in port | Open bases and leaky shrouds reduce capture efficiency. |
| Thickness planer | 450 to 650 CFM | 4 to 5 in port | High chip load benefits from smooth, short duct runs. |
| 8 in jointer | 400 to 550 CFM | 4 to 5 in port | Use enough velocity to keep heavy chips suspended. |
| Drum sander | 500 to 800 CFM | 4 to 6 in port | Fine dust loads filters quickly; include separator loss. |
| CNC router dust shoe | 600 to 900 CFM | 4 to 6 in hose | Large shoe skirts often need more CFM than the port suggests. |
| Duct inside diameter | Area | CFM at 3500 FPM | CFM at 4000 FPM |
|---|---|---|---|
| 3 in | 0.049 sq ft | 172 CFM | 196 CFM |
| 4 in | 0.087 sq ft | 305 CFM | 349 CFM |
| 5 in | 0.136 sq ft | 477 CFM | 545 CFM |
| 6 in | 0.196 sq ft | 687 CFM | 785 CFM |
| 7 in | 0.267 sq ft | 935 CFM | 1069 CFM |
| Fitting or restriction | Equivalent length used | Why it matters | Better shop choice |
|---|---|---|---|
| Long-radius 90 degree elbow | 6 duct diameters | Turning loss adds static pressure. | Use sweep elbows where space allows. |
| Wye or 45 degree lateral | 4 duct diameters | Branches disturb airflow less than tees. | Angle branch flow toward collector. |
| Blast gate in active path | 2 duct diameters | Gate slots and edges create turbulence. | Keep gates fully open during collection. |
| Corrugated flex hose | 3 times length | Ridges increase loss and trap chips. | Use the shortest flexible connection possible. |
| Collector type | Useful shop airflow | Typical static pressure | Best fit |
|---|---|---|---|
| Shop vacuum with separator | 100 to 180 CFM | High pressure, low CFM | Sanders, small ports, handheld tools. |
| 1 hp bag collector | 300 to 500 CFM | About 5 to 7 in. wc | One short 4 in run and moderate chips. |
| 1.5 to 2 hp single stage | 500 to 800 CFM | About 7 to 10 in. wc | Most single-machine small shop duct systems. |
| 2 to 3 hp cyclone | 700 to 1200 CFM | About 8 to 12 in. wc | Longer mains, 5 or 6 in ducts, fine dust capture. |
A dust collection system is a tool that is used to remove the sawdust and wood chip from the workspace. A dust collection system is important for three main reason: a dust collection system protect your lungs, a dust collection system protects your tools, and a dust collection system protects the quality of your work. Many people builds a dust collection system without calculating the necessary airflow, velocity, and pressure loss in the system, and this often cause the wood chips to settle within the ductwork.
Therefore, people must think about each of these three variable in creating their system for if the system is to work correct. The first factor to consider in the construction of the dust collection system is the airflow requirement of each of the machines. Each machine will have different requirement for the amount of airflow necessary to perform its tasks.
How to Build a Dust Collection System
For instance, a table saw may require three hundred fifty cubic feet of airflow per minute, but other machines might require more airflow than this. You should consider the required airflow for each machine when constructing the system to make sure that there is enough airflow for the machine that requires the most amount of airflow. Providing less airflow than one of the machines requires will create issues in the system.
The second factor to consider is the velocity at which the air move through the system. Air must move fast enough to ensure that the wood chips do not drop out of the moving air and become stuck in the ductwork. The velocity within the ductwork should be between thirty-five hundred and forty-five hundred feet per minute.
If the velocity is too low, then the chips will drop out of the air. If the velocity within the ductwork is too high, then too much static pressure will be created within the system, as well as too much noise created by the system. The third factor to consider is the static pressure within the system.
Every component of the system creates static pressure. Each component also removes some of the static pressure of the initial dust collector. For instance, long-radius elbow will create less static pressure than the sharp turn in a duct system.
Additionally, metal duct will create less static pressure than the flexible hoses for the system. A wye fitting will create less static pressure than a tee fitting because the wye allows the air to turn at an angle while the tee forces the air to turn ninety degree. The static pressure will tell you how much static pressure the dust collector creates, and whether or not it have enough static pressure left to move the air through the filter.
Another important consideration for the system is the inclusion of a reserve margin. A reserve margin is extra static pressure and airflow that is provided for the system. Even though many people do not consider this when they are building the system, a reserve margin of ten to twenty percent are included so that the system will still function when the filter is dirty.
If there is no reserve margin, then the system may fail when there is too much dust in the filter. Another variable that will impact the system is the diameter of the duct system. The diameter of the duct will have an impact on both the velocity and the static pressure of the system.
A smaller diameter for the duct allows the velocity to be high but will create more static pressure. A larger diameter will reduce the static pressure but will also reduce the velocity of the air within the duct. Another variable to consider is the condition of the filter.
The condition will change over time as the air passes through the system. A clean filter allows the air to move easily through the system but creates less static pressure. A dirty filter will create much higher static pressure for the system.
Because of this changeable factor, it is necessary to calculate the static pressure and airflow for both clean and dirty filter condition. Finally, the airflow that the dust collector provides should be the expected airflow rather than the peak airflow. Most dust collectors has a free-air rating but that is when there is no static pressure created by the system.
With the system connected and the filter loaded with wood chips the airflow will be less than the peak airflow. Rather than using the peak airflow values the system should calculate the static pressure and airflow values that it should expect in operation so that it knows that it has a correct margin of operation for its system.
