Lee Valley Lumber Thickness Gauge — and the Amazon Alternative
A dedicated gauge that reads board thickness at a glance. Lee Valley sells it direct; a digital caliper does the same job and much more.
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Lee Valley’s lumber thickness gauge is a simple, clever thing: a plate with graduated slots you slide a board into until it stops, reading the thickness off the slot. There is no adjustment, no battery and nothing to set — you sort a stack of rough stock by thickness as fast as you can pick boards up.
Like everything Lee Valley makes under its own name, it is sold direct at leevalley.com and is not on Amazon.
If sorting lumber quickly is the specific problem, buy it from them. For most shops, though, thickness is one measurement among many, and a caliper that reads all of them is the better spend.
Why fraction mode matters more than it sounds
Most woodworking in the US and much of the second-hand machinery world is dimensioned in fractions. A caliper that reads 0.7656 in is technically correct and practically useless — you then have to work out that this is 49/64, or close enough to 3/4 that the difference is a saw kerf.
A caliper with a fraction mode displays 3/4 in directly. That single feature removes a whole class of arithmetic error, and it is worth choosing a caliper for.
What else it measures
Thickness, obviously. But also: the depth of a mortise, using the depth rod. The inside width of a groove, using the inside jaws. A tenon’s thickness at three points along its length, to find where it is tapered. The actual diameter of a drill bit that has lost its markings. The step in a rebate. The gap in a joint you are trying to diagnose.
That range is why a caliper ends up in a pocket rather than a drawer.
Workshop realities
Sealed to IP54 is not waterproof, but it keeps fine dust out of the slide, which is what kills unsealed calipers in a wood shop.
Switch it off. Digital calipers draw current whenever the display is on, and the most common complaint about every model is a dead battery — almost always because it was put away live.
And treat it as an instrument. Dropped on concrete, a caliper’s jaws go out of parallel, and it will then read confidently and wrongly for the rest of its life.
What works
- Fraction mode reads out 3/4 in and 13/16 in directly, which removes the decimal-to-fraction conversion that causes most measuring mistakes in an imperial shop
- It measures far more than thickness — depth, internal dimensions, tenon shoulders, drill bits and the step in a rebate all come off the same tool
- IP54 sealing means sawdust does not immediately get into the slide, which is the usual death of a cheap caliper in a workshop
What doesn't
- It is slower than a dedicated thickness gauge: you have to open the jaws, close them on the board and read, where a slot gauge is one movement
- The battery dies in a drawer if the caliper is stored switched on, and they always seem to be switched on
- A caliper is a precision instrument that resents being dropped, and workshop floors are concrete