Tolerance Calculator: Set Min and Max Limits Without Errors

By Robert Low, Director, Lead Auditor & BRCGS Approved Trainer

Every check sheet needs a minimum and a maximum, and every day someone gets the arithmetic wrong. My free tolerance calculator takes a nominal value and a tolerance and gives you the limits.

What the Tolerance Calculator Does

You tell it the nominal value and the tolerance, and it returns the minimum and maximum. It sounds trivial, and it is, which is exactly why people make mistakes with it: percentage against absolute tolerances, plus against minus, and rounding.

Setting limits correctly once, in one place, and then copying them to your records, saves a lot of arguments later.

How to Use It

1. Open the Tolerance Calculator on the free resources page.
2. Enter the nominal value.
3. Enter the tolerance, and check whether it is an absolute value or a percentage.
4. Copy the minimum and maximum onto your check sheet or specification.

Where It Helps Beyond Certification

Clear limits are the foundation of defensible decisions. If an operator rejects a product because it is outside a limit, that limit needs to be written down and right. The same limits feed your complaint investigations and your supplier specifications.

It is also useful at the quoting and design stage, when you are agreeing what a customer actually needs and want to see what a tolerance looks like in real numbers.

Where Sites Get Caught Out

Watch the units and the type of tolerance. A tolerance of 2 percent on a 500 gram fill is not the same as 2 grams. Write the unit next to every limit on your check sheets.

Related free tools: Process Capability.