← AskMachinist · Guides · Calculator
Metric Gage Block Stacks
Metric gage block sets build any size to 0.0005 mm (with the 1.0005 block) or 0.001 mm from a handful of blocks. The method is the same as inch: clear the rightmost decimal digit first, then work left, so the stack uses as few blocks (and wringing films) as possible.
What's in a typical metric set
| Series | 88-piece | 112-piece |
|---|---|---|
| Half-micron block | 1.0005 | 1.0005 |
| 0.001 mm steps | 1.001–1.009 (9) | 1.001–1.009 (9) |
| 0.01 mm steps | 1.01–1.49 (49) | 1.01–1.49 (49) |
| 0.5 mm steps | 0.5–9.5 (19) | 0.5–24.5 (49) |
| Large blocks | 10–100 in 10s (10) | 25, 50, 75, 100 (4) |
These are the Mitutoyo-style 1 mm-base sets the calculator uses. Other makers' sets differ; check the list in your box.
Step by step: 41.125 mm with an 88-piece set
- Thousandths (0.005): take 1.005. Remainder 41.125 − 1.005 = 40.120.
- Hundredths (0.12): take 1.12. Remainder 39.000.
- Halves and units (9): take 9. Remainder 30.000.
- Tens (30): take 30. Done: 30 + 9 + 1.12 + 1.005 = 41.125 mm, four blocks.
If a remainder lands on a block you don't have (or one that's worn), take the next block that keeps the right-hand digits clear and repeat. The free calculator lets you untick missing blocks and does this search for you.
Worked examples
Stacks below were produced by the same solver the calculator uses (shortest stack first).
| Target | Set | Stack | |
|---|---|---|---|
| 41.125 mm | 88-piece | 30 + 9 + 1.12 + 1.005 | open |
| 63.457 mm | 88-piece | 60 + 1.45 + 1.007 + 1 | open |
| 27.385 mm | 112-piece | 25 + 1.38 + 1.005 | open |
| 8.7535 mm | 88-piece | 5.5 + 1.25 + 1.003 + 1.0005 | open |
| 125.678 mm | 112-piece | 100 + 23.5 + 1.17 + 1.008 | open |
Tips for metric stacks
- Fewer blocks is better: every wringing film and every block's tolerance adds up. See gage block grades.
- Use the 1.0005 block only when you truly need the half-micron; most shop work stops at 0.001 mm.
- Let the stack and the part soak to the same temperature; aluminium against steel blocks moves fast. Use the temperature correction tool.
- Need an angle? Get the stack height from the sine bar calculator, then build it here.
- Wring thick blocks first, thin ones last: how to wring gage blocks.