FoldSpecGuides
How to measure board caliper
Use the actual production stock instead of a generic thickness assumption.
Use a suitable gauge
A micrometer or thickness gauge gives a more reliable result than a ruler. Take several measurements away from crushed edges and average the usable readings.
Condition the material
Humidity and handling can change paperboard and corrugated thickness. Measure stock that has been stored in conditions similar to the intended converting environment.
Record the source
Save the material name, supplier, lot and measured value with the prototype. That evidence is more useful than relying on a preset label alone.