# Uncertainty Measurement - What this accuracy specification "1% + 10^5": means?

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#### akmal122g

Hello. Can someone help me what this accuracy specification "1% + 10^5": means?

#### Hershal

##### Metrologist-Auditor
Trusted Information Resource
The 1% may be either of reading or full scale. That should be defined in the specification. Then add the 10^5. However, that likely should be 10^-5, otherwise the specification will be huge.

#### dgriffith

##### Quite Involved in Discussions
Agree. Usually, by convention in the US anyway, a percentage without definition or clarification is 'of reading'. So, 1% of reading, plus 100,000 inches is my kind of specification.
Hershal is right. That should be 10e-5. Otherwise, we need more context to understand.
If the reading is 0.01, then 0.01x.01=0.0001 + 10e-5 = 0.0001+0.00001=0.00011. This is what it is, but
this is what it means:
The uncertainty value for the reading specification changes proportionally with the reading, but the 10e-5 will always be 10e-5. The uncertainty will never be less than that, even if the reading was zero.

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