TPI stands for Teeth Per Inch, and it tells you how many cutting teeth are packed into each inch of a saw blade. A blade with 6 TPI has six teeth per inch and cuts aggressively, while a blade with 24 TPI has much finer teeth and produces smoother, slower cuts. Understanding this single number is the fastest way to pick the right blade for any material and thickness.
How TPI Is Measured
TPI is counted from gullet to gullet, not from tooth tip to tooth tip. The gullet is the curved valley at the base of each tooth. You count only the full teeth that fit within one inch of blade.
You may also see the term PPI, or Points Per Inch, especially on hand saws. PPI counts the peaks (tips) of the teeth instead of the full teeth. Because of this difference, PPI is always one number higher than TPI for the same blade. A saw labeled 5 PPI is identical to one labeled 4 TPI. If you’re shopping for hand saws and see both terms, just remember: subtract one from PPI to get TPI.
Why TPI Changes Everything About a Cut
The number of teeth per inch controls three things at once: cutting speed, surface finish, and chip removal. These are all connected through a simple tradeoff.
Lower TPI blades (fewer, larger teeth) have bigger gullets. Those deeper valleys between teeth can carry away more material per stroke, which means faster cutting through thick stock. The downside is a rougher edge with more visible saw marks. Higher TPI blades (more, smaller teeth) produce cleaner cuts with minimal burrs, but the smaller gullets can only clear tiny chips at a time, so cutting is slower.
Choosing the wrong direction causes real problems. Using too coarse a blade on thin material lets the widely spaced teeth grab and tear the workpiece instead of cutting it cleanly. Using too fine a blade on thick material clogs the gullets with chips that have nowhere to go, generating friction, heat, and eventually a blade that binds or dulls prematurely.
The 3-Tooth Rule
The most reliable way to pick the right TPI is the “three teeth in the material” rule. At any point during a cut, at least three teeth should be in contact with the workpiece. For thick lumber or solid metal bar stock, that’s easy to achieve with a low TPI. For thin sheet metal or tubing, you need a much higher TPI to keep enough teeth engaged.
As a general guideline, aim for 3 to 6 teeth in the workpiece when cutting wood and soft materials, and 6 to 24 teeth in the workpiece for metals and harder materials. The key variable is material thickness, not just material type. A thin piece of steel needs a higher TPI than a thick piece of steel.
TPI Ranges by Material
For wood, most blades fall between 3 and 10 TPI. Rough crosscuts and demolition work sit at the low end. Finish cuts in hardwood or plywood push toward the higher end. Soft plastics and composite materials behave similarly to wood and do well with lower TPI blades that have large gullets for chip clearance.
For metals, the range typically spans 14 to 24 TPI. Aluminum is an exception: because it’s soft and tends to clog teeth, a slightly lower TPI with bigger gullets often works better. Steel and stainless steel follow the thickness rule more strictly. A steel tube with a wall thickness of about 4mm (roughly 5/32″) works well with an 18 TPI blade. Drop that wall thickness to 1/8″ and you’d want a 24 TPI blade for a clean cut with minimal burr. A 2-inch solid piece of metal, by contrast, also calls for around 18 TPI because you already have plenty of teeth engaged across the full width.
Variable TPI Blades
Not every blade has uniform tooth spacing. Variable pitch blades alternate between two different TPI counts along the same blade, often expressed as something like 10/14 TPI. This design has become the industry standard for bandsaw and reciprocating saw blades, and for good reason.
When teeth are evenly spaced, the blade can fall into a rhythmic vibration pattern called harmonics. That vibration accelerates wear, particularly on carbide-tipped teeth, which are extremely hard but brittle enough to chip under sustained vibration. By varying the spacing between teeth, the cutting rhythm is constantly interrupted. The result is less vibration, quieter operation, and better chip evacuation. Variable pitch blades are especially useful when cutting structural shapes, tubing, and solid bar stock where the blade passes through changing thicknesses in a single cut.
Picking the Right TPI for Common Tools
Reciprocating Saws
Reciprocating saw blades cover the widest TPI range because these tools handle everything from demolition to metal cutting. Wood demolition blades typically run 6 to 10 TPI. Metal-cutting blades range from 14 to 24 TPI, with the exact choice depending on material thickness. For mixed demolition work (cutting through walls with nails, pipes, and wood), blades in the 8 to 14 TPI range or variable pitch designs offer the best versatility.
Jigsaws
Jigsaw blades for wood generally fall between 6 and 12 TPI. Lower counts handle fast, rough cuts in thick lumber. Higher counts give you smoother curves in thinner stock or plywood. Metal-cutting jigsaw blades start around 14 TPI and go up to 24 or higher for thin sheet metal, where keeping enough teeth engaged prevents the blade from catching and buckling the material.
Bandsaws
Bandsaw blade selection relies heavily on the three-tooth rule because these machines cut such a wide variety of stock sizes. A skip-tooth blade design with low TPI and extra-deep gullets works well for softer materials like wood, plastic, and non-ferrous metals where chips are large and need room to clear. For steel and other hard metals, finer TPI blades with variable pitch reduce vibration and produce cleaner cuts.
Hand Saws
Traditional hand saws for rough carpentry work sit around 4 to 7 TPI (or 5 to 8 PPI). Saws designed for joinery and fine woodworking run 10 TPI and above. If you’re buying a hand saw and the packaging lists PPI instead of TPI, subtract one to compare it against TPI recommendations.
Quick Reference by TPI Count
- 3 to 6 TPI: Fast, rough cuts in thick wood, plastic, and soft materials. Large gullets clear chips quickly. Expect a coarse finish.
- 6 to 10 TPI: General-purpose wood cutting. Balances reasonable speed with a decent finish. Common for circular saw and reciprocating saw blades.
- 10 to 14 TPI: Fine woodworking cuts and the transition zone into softer metals like aluminum. Good for thinner wood stock where smoothness matters.
- 14 to 18 TPI: General metal cutting. Works for steel, copper, and thicker non-ferrous metals. Keeps enough teeth in contact with medium-thickness stock.
- 18 to 24 TPI: Thin metal, sheet metal, and thin-walled tubing. Prevents grabbing and deformation. Produces the smoothest edges with the least burr.