What do as-found and as-left mean?

As-found is the reading taken before anything is adjusted, cleaned or repaired. As-left is the reading after that work. Recording both answers the question that matters after a drift is discovered. Was the instrument in tolerance while it was in service? If not, what did it measure in the meantime?

Why does as-found matter more than as-left?

As-left tells you the instrument is fine now. As-found tells you whether the work it did since its last calibration can be trusted. An out-of-tolerance as-found result is what triggers a review of the measurements and product that instrument touched, so a certificate that reports only the as-left condition has removed the evidence you would need.

How many points should a calibration have?

It depends on the instrument and the standard you work to, not on a universal rule. Common practice is to cover the working range with points near the extremes and through the middle, often five or ten, and to include any point the instrument is habitually used at. The right answer is the one your procedure states and your assessor can see you followed.

What is temperature compensation and when do I need it?

Materials expand and contract with temperature, so a dimensional measurement taken away from the 20 C reference is not the length you would have measured at 20 C. Compensation corrects for that. You need it for dimensional work at a temperature other than 20 C with a material whose expansion is significant relative to your tolerance. You do not need it for pressure, electrical or temperature calibration, which is why it is switched off here by default.

What formula does the temperature correction use?

The standard first-order correction to the 20 C reference: corrected = measured minus measured multiplied by alpha multiplied by (T minus 20), where alpha is the linear coefficient of thermal expansion of the item in units of 10^-6 per degree C and T is the temperature at the time of measurement. The coefficients offered here are nominal handbook values. A laboratory reporting to a stated uncertainty should use its own material data and account for the uncertainty of the temperature measurement itself.

Does an out-of-tolerance as-found result mean the instrument failed?

It means the instrument was outside its acceptance limit when it arrived, which is a finding rather than a verdict. The action it demands is an assessment of what that instrument measured since it was last known good. Most quality systems expect that assessment to be documented, along with what was contained, reworked, re-inspected or notified.

Does this worksheet leave my browser?

No. Everything runs in your browser. Nothing you type is sent to us, so we never see your readings and have nothing to store. Use the copy or CSV buttons to keep the result in your own records.

As-found / as-left calibration worksheet

An as-found / as-left worksheet records an instrument's reading at each test point before any adjustment (as-found) and after the work (as-left). As-found shows whether the instrument was in tolerance while it was in use. As-left shows the condition it goes back into service in. A 10-point calibration checks ten evenly spaced points across the range.

Download the Excel worksheet .xlsx, 16 KB, 3 sheets

Generate your test points, record both readings at each one, and see the error and the verdict as you type. Optional temperature compensation corrects dimensional readings to the 20 °C reference. Nothing you enter is sent anywhere. Everything runs in your browser, and you don't need to sign up or give an email.

1. Set up the calibration

Instrument or asset ID

Unit

Tolerance, ±

Applied to every row. Override any single row in its own cell.

Date

2. Generate your test points

Enter the range and how many points you check. The nominal column fills itself, evenly spaced, so a ten-point calibration is one click instead of ten rows of typing.

Range from

Range to

Number of points

3. Temperature compensation (optional)

Correct dimensional readings to 20 °C

4. Record the readings

No adjustment made

Tick No adjustment made and the as-left column mirrors as-found, which is the usual case when an instrument arrives in tolerance. Press Enter in any reading cell to drop to the next row.

#	Nominal	As found	As left	Tolerance ±	Found error	Left error	Verdict	Remove

Result

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Send us what you have, in any format, and we load it into Axiospec for you. We keep your instrument IDs and intervals. It usually takes a couple of business days, and it's free on every plan.

How the move works

This worksheet does the arithmetic. Axiospec keeps the as-found and as-left readings on the instrument itself, where an auditor can find them.

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Why both readings belong on the certificate

An as-left reading tells you the instrument is good now. That is the easy half. The as-found reading is the one that carries the risk, because it tells you what condition the instrument was in while it was doing work you have already shipped.

When an as-found reading comes back outside the acceptance limit, the finding is not really about the instrument. It is about every measurement that instrument made since it was last known good, and about the product those measurements passed. That is the assessment most quality systems expect you to document, and you cannot start it from a certificate that records only the as-left condition.

The practical answer is to record both readings at every point, rather than one summary verdict for the whole instrument. A device can be comfortably in tolerance at mid-range and out at the top of its span. Only a point-by-point record shows which measurements are in question.

When temperature compensation matters

Dimensional metrology is referenced to 20 °C. A steel part measured at 26 °C is genuinely longer than the same part at 20 °C. If your tolerance is tight enough, that difference is not noise but the whole margin. A 100 mm steel length at 26 °C carries a correction of roughly 0.0069 mm, which is most of a 0.01 mm tolerance before you have measured anything.

Compensation here is optional and off by default. As-found and as-left apply just as much to pressure, electrical and temperature calibration, where correcting for linear expansion would be meaningless. Switch it on for dimensional work away from 20 °C, and leave it off otherwise.

Frequently asked questions

What do as-found and as-left mean?: As-found is the reading taken before anything is adjusted, cleaned or repaired. As-left is the reading after that work. Recording both answers the question that matters after a drift is discovered. Was the instrument in tolerance while it was in service? If not, what did it measure in the meantime?
Why does as-found matter more than as-left?: As-left tells you the instrument is fine now. As-found tells you whether the work it did since its last calibration can be trusted. An out-of-tolerance as-found result is what triggers a review of the measurements and product that instrument touched, so a certificate that reports only the as-left condition has removed the evidence you would need.
How many points should a calibration have?: It depends on the instrument and the standard you work to, not on a universal rule. Common practice is to cover the working range with points near the extremes and through the middle, often five or ten, and to include any point the instrument is habitually used at. The right answer is the one your procedure states and your assessor can see you followed.
What is temperature compensation and when do I need it?: Materials expand and contract with temperature, so a dimensional measurement taken away from the 20 C reference is not the length you would have measured at 20 C. Compensation corrects for that. You need it for dimensional work at a temperature other than 20 C with a material whose expansion is significant relative to your tolerance. You do not need it for pressure, electrical or temperature calibration, which is why it is switched off here by default.
What formula does the temperature correction use?: The standard first-order correction to the 20 C reference: corrected = measured minus measured multiplied by alpha multiplied by (T minus 20), where alpha is the linear coefficient of thermal expansion of the item in units of 10^-6 per degree C and T is the temperature at the time of measurement. The coefficients offered here are nominal handbook values. A laboratory reporting to a stated uncertainty should use its own material data and account for the uncertainty of the temperature measurement itself.
Does an out-of-tolerance as-found result mean the instrument failed?: It means the instrument was outside its acceptance limit when it arrived, which is a finding rather than a verdict. The action it demands is an assessment of what that instrument measured since it was last known good. Most quality systems expect that assessment to be documented, along with what was contained, reworked, re-inspected or notified.
Does this worksheet leave my browser?: No. Everything runs in your browser. Nothing you type is sent to us, so we never see your readings and have nothing to store. Use the copy or CSV buttons to keep the result in your own records.

This worksheet runs entirely in your browser. Nothing you type leaves the page, and no result is stored.

As-found and as-left readings explained Guard band & decision rule Calibration log template Measurement uncertainty budget Torque wrench calibration record All tools

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Axiospec records as-found and as-left on the instrument, flags the out-of-tolerance ones, and keeps the certificate with the record.

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