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How to Build a Gage Block Stack

Guide · Updated October 27, 2026

A gage block stack is a set of blocks wrung together to make one exact size. The trick is choosing blocks so the stack uses as few blocks as possible: fewer blocks means fewer tolerances adding up and fewer wringing joints. Here's the hand method machinists use, with worked inch and metric examples.

Skip the arithmetic

Type a size into the free Gage Block Calculator and it shows the fewest-block stack for 36, 81, 88 and 112-piece sets, with optional wear blocks. Free, no login.

1. Subtract wear blocks first

If you protect the stack with wear blocks, take them off the target before anything else: 2 × 0.050" = 0.100" for a typical inch set, or 2 × 1 mm (or 2 × 2 mm) for metric. Build the remainder, then add one wear block on each end. More in gage block care & wear blocks.

2. Clear the rightmost digit, then work left

Pick the block that makes the last decimal digit of the remainder zero. Subtract it, then do the same for the next digit to the left, until a large block finishes the job.

Inch example: 1.2345" with an 81-piece set

Ten-thousandths (0.0005): take 0.1005. Remainder 1.2345 − 0.1005 = 1.1340.
Thousandths (0.134): take 0.134. Remainder 1.0000.
Inches: take 1.000. Done: 1.000 + 0.134 + 0.1005 = 1.2345", three blocks.

Inch example: 3.4567" with an 81-piece set

0.1007 → remainder 3.3560.
0.106 → remainder 3.2500.
0.250 → remainder 3.0000.
3.000. Done: 3.000 + 0.250 + 0.106 + 0.1007 = 3.4567", four blocks.

Metric example: 41.125 mm with an 88-piece set

1.005 → 40.120; 1.12 → 39.000; 9 → 30.000; 30. Stack: 30 + 9 + 1.12 + 1.005 = 41.125 mm. Full walk-through in metric gage block stacks.

3. Aim for the fewest blocks

Each block carries its own grade tolerance, so a 3-block stack beats a 6-block stack. See gage block grades explained.
If a remainder lands on a block you don't have, or one that's worn, pick the next block that still clears the right-hand digits and repeat.
Big sets build mid-size stacks with fewer blocks: compare in how to choose a gage block set.
Always add the blocks back up and confirm the total equals the target.

4. Wring thickest first

You plan from the smallest digit, but you wring from the thickest block. Wring the thick blocks together, then slide each thin block onto a thick one (never twist it, never wring two thin blocks together), and finish with a wear block on each end, marked face out. Step-by-step in how to wring gage blocks.

5. Mind the temperature

Gage blocks are sized at 68 °F (20 °C). Steel grows about 6.4 µin per inch per °F, so a 4" stack warmed 5 °F by your hands is long by about 0.000128". Handle by the edges, let the stack sit on the plate to normalize, and use the temperature correction tool when part and blocks differ. Background: gage block temperature compensation.

Worked stacks to copy

Checked examples: 1.2345", 3.4567", 25.4 mm, the fractional inch chart, or all gage block stacks.

FAQ

How do you work out which gage blocks to use?

Clear the rightmost decimal digit first, then work left. For 1.2345 in with an 81-piece set: 0.1005 clears the last digit, 0.134 clears the thousandths, and 1.000 finishes it: 1.000 + 0.134 + 0.1005.

Why use the fewest gage blocks?

Every block adds its own tolerance and every joint adds a wringing film and a chance for dirt or heat error. Fewer blocks means a more accurate, quicker stack.

What order should I wring gage blocks in?

Plan the stack from the smallest digit, but wring the thick blocks together first, then slide the thin blocks onto thick ones. Never wring two thin blocks together.

Do wear blocks count in the stack size?

Yes. Subtract both wear blocks first (2 × 0.050 in or 2 × 1 mm), build the remainder, then put a wear block on each end with the marked face out.

Is there a free gage block stack calculator?

Yes. The Gage Block Calculator at gageblockcalc.com finds the fewest-block stack for inch and metric sets, with optional wear blocks. Free, no login.

Related guides and calculators

Gear for building stacks

HFS 36-piece inch gage block set: a compact inch set.
Mitutoyo 516-938-26 112-piece metric set: a full metric set.
Mitutoyo 0.050" steel square gage block: handy as a wear block.

Build your stack in seconds

The free Gage Block Calculator finds the fewest-block combination for inch and metric sets, with wear blocks. No login.

Questions? Ask a machinist.

General shop information only — follow your gage manufacturer's instructions and your quality system. As an Amazon Associate I earn from qualifying purchases; links marked "sponsored" may earn a commission at no cost to you.