MIN / MAX Minimum / maximum limit
Minimum / maximum limit · Indicadores dimensionales · ISO 1101 + ASME Y14.5
Example in plan
How to interpret it
On the drawing, “Wall thickness 3 MIN · Boss height 12 MAX” states a minimum / maximum limit requirement.
What controls
Dimension limited in one direction only: the stated value may not be exceeded downward (minimum) or upward (maximum), and in the other direction there is no explicit limit beyond what other dimensions on the part impose. It is used when the function only requires one side to be guaranteed: a wall thickness that must not get thinner, a height that must not protrude, a thread length that must be present as a minimum. It is not the same as a unilateral tolerance on a nominal, where the other limit is defined.
How to verify
With the instrument appropriate to the quantity, comparing only against the stated limit: there is no mid value or symmetric tolerance to evaluate. In production inspection, a single-limit gauge settles the check immediately. For wall thicknesses on hollow parts, the usual method is an ultrasonic thickness gauge, because there is no access from both sides.
Common mistakes when interpreting it
- Treating the value as a nominal and aiming for it instead of staying on the safe side.
- Confusing it with the maximum and least material condition concepts of geometric tolerancing, which are something else.
- Chaining several limit dimensions without checking the resulting geometry in the worst case.
How to get it in the workshop / if it comes out of tolerance
Be clear about which side the limit is on and machine with margin toward the free side, which is what gives the process room. Watch out when several limit dimensions are chained on the same part: each one is free on its own side, but the combination can produce impossible geometry or parts much heavier than intended. And check that no other dimension is implicitly limiting the side that appears to be free.
Dimension below a minimum: usually cannot be fixed if it means missing material, so it should be checked before the final operations, not at the end. Dimension above a maximum: can usually be corrected by removing material, after checking that another dimension is not compromised. If a limit dimension fails repeatedly, check whether the process is running too close to the limit instead of with margin toward the free side.
Other symbols in Dimension indicators
Related tools
ISO fits
Calculates indicative ISO 286 tolerances for shaft and hole, H7/g6, H7/h6, H7/k6 and H7/p6 fits with clearance, transition and interference graph.
Inspection Plans
Upload a plan, extract dimensions and GD&T with AI and export your inspection guideline in PDF or CSV.
Shop trigonometry
Workshop trigonometry: right triangle, C chamfer, Z countersink, sine bar, taper and polar→X/Y for CNC operators.