Calibration log template
Build a calibration register you can actually use. Enter each instrument with its last calibration date and interval, and the tool works out the next-due date and flags every gauge that is overdue or due within 30 days. Export it as CSV or paste it straight into Excel. Everything runs in your browser and nothing you type is uploaded.
Your instruments
Edit the example rows or clear them and enter your own. The due date is worked out from the last calibration date and the interval. Scroll the table sideways on a narrow screen.
| # | Asset tag | Description | Last cal | Interval | Due date | Result | Technician | Cert # | Standard | Remove |
|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2026-09-09 | |||||||||
| 2 | 2026-07-27 | |||||||||
| 3 | 2027-05-07 |
The CSV includes the computed due date and a due-status column worked out from today’s date, so the file you hand to a colleague already says which instruments need chasing.
Summary
How to build a calibration log that survives an audit
What a calibration log actually is
A calibration log is the controlled record of the measuring and test equipment you depend on and the state each one is in. People call it a calibration register, a calibration record, or a gauge list, and most of the time it started as a calibration log template someone downloaded years ago. It is the answer to a question a technician asks every day and an auditor asks once a year: is this instrument in calibration right now, and where is the proof.
The log is not the control. The control is the process behind it: how an instrument gets into the system, how its interval is set, how it is recalled when it comes due, and what happens when it comes back out of tolerance. The log is simply where that process leaves its fingerprints. A list of gauge numbers is an inventory. A list that records the last calibration, the due date, the result, and the certificate behind each one is a record.
What ISO 9001 clause 7.1.5 requires
ISO 9001:2015 clause 7.1.5 is titled monitoring and measuring resources. It requires you to determine and provide the resources needed to make sure your monitoring and measuring results are valid and reliable, and to keep documented information as evidence that those resources are fit for purpose. Where measurement traceability is a requirement, or where you judge it necessary to have confidence in the results, clause 7.1.5.2 adds four things that a calibration log exists to carry.
The measuring equipment has to be calibrated or verified, or both, at defined intervals or before use, against measurement standards traceable to international or national measurement standards. It has to be identified so its calibration status can be determined, which is what the asset tag and a calibration label on the instrument do together. It has to be safeguarded from adjustments, damage, or deterioration that would invalidate its status. And when an instrument is found to be unfit, you have to determine whether the validity of previous results has been affected and take action. That last sentence is why the result column and the certificate number matter: without them, an out-of-tolerance investigation has nowhere to start.
What ISO/IEC 17025 adds
If you run a calibration or testing laboratory, ISO/IEC 17025:2017 is more explicit. Clause 6.4 covers equipment: it has to be calibrated when measurement accuracy or uncertainty affects the validity of results, it has to be labelled or otherwise identified with its calibration status including the date last calibrated and the date or criteria for next calibration, and records have to be kept of each item that can affect laboratory activities. Clause 6.5 covers metrological traceability, the unbroken chain of calibrations back to a national or international reference, which is the chain the certificate number in your log points into.
Clause 7.8 then governs the reporting of results, and clause 7.11 governs control of data and information management. Taken together they mean a laboratory calibration log is not just a convenience, it is a required record: for each item you can affect results with, its identity, its status, and the evidence behind that status all have to be retrievable. The same equipment clause is why a good log carries a location and an in-service or out-for-calibration state, so that an instrument that is away being calibrated is not quietly assumed to be on the bench.
The columns a useful log has, and why
Most calibration log templates fail in one of two directions. They are too thin to answer a question, or so wide that nobody keeps them current. These are the columns that earn their place.
- Asset tag. A unique, permanent ID for the instrument, matched by a physical label on the tool. This is the anchor the whole record hangs from, and the thing a calibration certificate and a measurement record both point back to. Two calipers of the same model need two different tags.
- Description. What the instrument is and its range, specific enough to tell two similar tools apart. Digital caliper, 0 to 150 mm is a description. Caliper is a guess.
- Last calibration date. The date the current calibration was completed. It is the anchor the due date is calculated from and the date an as-found result is tied to.
- Interval. How long the calibration is valid for, in months. Start from a default and adjust it from the instrument history rather than treating one number as fixed forever.
- Next-due date. When the instrument has to be recalled. This is the only field on a typical log that changes state on its own, and the one the whole log exists to watch. The builder above computes it for you.
- Result. The as-found outcome of the last calibration: in tolerance, out of tolerance, adjusted, or limited. A pass or fail is not enough, because an out-of-tolerance as-found result is what triggers a review of everything the instrument measured since it was last known good.
- Technician or laboratory.Who performed the calibration, whether an internal technician or an external provider. It is how you tie the entry to a competent person and, for external work, to an approved supplier.
- Certificate number. The link from the row to the actual calibration certificate, the traceable evidence behind the entry. A row with no certificate number is an assertion, not a record.
- Standard or procedure. What the calibration was performed to, whether an accredited scope under ISO/IEC 17025, an internal procedure, or a specification. It tells an auditor the basis for the calibration and links the entry to the method behind it.
The builder above uses this core set so the export stays readable. Add location, range, or an in-service status as extra columns in the CSV once you have it in a spreadsheet, and keep the column set stable afterwards, because a log that changes shape every quarter cannot be trended.
How to set and calculate the due date
The usual method is simple arithmetic: add the interval to the last calibration date. A gauge calibrated on the tenth of June with a twelve-month interval is due the following tenth of June. The builder above does exactly this, and then compares the due date to today to tell you whether the instrument is current, due within 30 days, or already overdue.
Two refinements are worth knowing. First, some programs count the next interval from the previous due date rather than the actual completion date, so that a late calibration does not quietly push every future due date later and let the interval drift. Second, no standard fixes the interval itself: it is meant to be set from the instrument, its use, its stability, and the consequence of it being wrong, and then adjusted from history. An instrument that keeps coming back in tolerance can have its interval extended with justification; one that drifts should have it shortened. A fixed twelve months for everything is a starting point, not an answer.
When an instrument comes back out of tolerance
An as-found out-of-tolerance result is the case the whole record is built to handle. Because the instrument was outside its accuracy limits when it arrived, every measurement it took since its last known-good calibration is in question. The response is an impact assessment: what did this gauge measure, how far out was it, and does that matter for the product or the decisions made with those measurements. This is exactly what ISO 9001 clause 7.1.5.2 means by determining whether the validity of previous results has been adversely affected.
The record makes the assessment possible. The last calibration date bounds the period at risk, the certificate number leads to the numbers behind the failure, and the asset tag lets you find everywhere the instrument was used. A log that only records a pass or fail throws that away, and recording the as-found values, not just the verdict, is what separates a log you can investigate from one you cannot.
What an auditor actually asks
Calibration audits tend to follow the same path, and they start from the floor rather than from your log. The auditor walks up to an instrument in use, reads the asset tag or the calibration label, and then asks: show me this one in your log, show me its current calibration certificate, and show me it is not overdue. If the instrument on the bench is not in the log, or the label says it came due last month, the finding writes itself.
The two most common findings in this area are not conceptual, they are clerical. The first is an instrument still in service past its due date. The second is an out-of-tolerance result with no record of an impact assessment. Both are avoidable, and the first is exactly what the due-date flags in the builder above are aimed at. Export or print the log before an audit, but keep the live version somewhere that can tell you when a date has gone by.
Where the spreadsheet stops working
A spreadsheet is a perfectly good calibration log template for a small inventory. It stops being enough for a simple reason: a spreadsheet does not tell anyone that a due date has passed. Instruments come due quietly, and the file only speaks when somebody opens it. Add a few dozen gauges, several intervals, an out-of-tolerance result to chase, and two people editing separate copies, and the log drifts away from reality without anyone doing anything wrong.
That is the gap worth closing first, and it is a small one: last calibration dates, intervals, and due dates held in one place that watches the calendar for you and tells the right person before an instrument goes overdue. Everything else on a calibration program wish list can wait until that is solid.
Common questions
What is a calibration log?
A calibration log, also called a calibration register or calibration record, is the controlled list of the measuring and test equipment you rely on and the state of each one. A useful log identifies the instrument by a unique asset tag, describes it, and records when it was last calibrated, when it is next due, the interval between the two, the result of the last calibration, who performed or witnessed it, and the certificate number that backs it up. It is the single place that answers the question an auditor asks first: is this gauge in calibration right now, and where is the evidence.
What should a calibration log include?
At minimum: a unique asset or ID tag, a description of the instrument, the last calibration date, the calibration interval, the next-due date, the result of the last calibration such as in tolerance or out of tolerance, the technician or laboratory, the calibration certificate number, and the standard or procedure the calibration was performed to. Range, location, and the status of the instrument such as in service, out for calibration, or retired are common additions. A good test is simple: anything you would have to go hunting for during an audit belongs in the log.
Does ISO 9001 or ISO/IEC 17025 require a calibration log?
Neither standard uses the exact words calibration log, but both require the records a log holds. ISO 9001:2015 clause 7.1.5 requires monitoring and measuring resources to be suitable, calibrated or verified against traceable standards at defined intervals, identified so their calibration status is known, and safeguarded, with documented information kept as evidence. ISO/IEC 17025:2017 clause 6.4 covers equipment and calibration status and clause 7.5 covers technical records. A maintained log is the simplest way to satisfy both, which is why nearly every quality system has one.
How do I calculate the next calibration due date?
The common method is to add the calibration interval to the date of the last calibration. If a caliper was calibrated on the fifteenth of March with a twelve-month interval, it is due the following fifteenth of March. This builder does that for you: enter the last calibration date and pick an interval, and it works out the due date and tells you whether the instrument is current, due within 30 days, or already overdue. Some programs count from the due date rather than the actual completion date so that intervals do not drift, and higher-risk instruments often carry shorter intervals set from their history rather than a default.
What does in tolerance versus out of tolerance mean on a calibration record?
In tolerance, sometimes recorded as as-found in tolerance, means the instrument was found to be within its stated accuracy when it arrived for calibration, so any measurements it took beforehand can be trusted. Out of tolerance means it was outside its accuracy limits as found, which can call into question the measurements made since its last calibration and usually triggers an impact review. Adjusted means it was brought back into tolerance during calibration, and limited means only part of its range or function was calibrated. Recording the as-found result, not just a pass or fail, is what makes an out-of-tolerance investigation possible later.
How often should instruments be calibrated?
No standard fixes a single frequency. Twelve months is a common default, but the right interval depends on the instrument, how heavily it is used, how stable it is, and the consequence of it being wrong. The defensible approach is to start from a sensible default and then lengthen or shorten each interval based on the instrument history: if it keeps coming back in tolerance you can extend it, and if it drifts you shorten it. Instruments tied to critical measurements, or ones that have gone out of tolerance before, are commonly calibrated more often.
What is the calibration certificate number for?
The certificate number is the link from the row in your log to the actual calibration certificate, which is the traceable evidence behind the entry. When an auditor picks an instrument off your log and asks to see the proof, the certificate number is how you find it. It is also how you tie a calibration back to the reference standards and their own traceability, which is the chain that ends at a national metrology institute. A log entry with no certificate number is an assertion; one with a certificate number is a record.
Is a spreadsheet good enough for a calibration log?
A spreadsheet is a perfectly good calibration log template for a small inventory. It stops being enough for one reason: a spreadsheet does not tell anyone that a due date has passed. Instruments come due quietly and the file only speaks when somebody opens it. Add a few dozen instruments, different intervals, and more than one person editing copies, and the log drifts away from reality. That is the gap worth closing first, and it is a small one: due dates that watch the calendar for you rather than waiting to be read.
This builder is a starting point for your own calibration log, not a compliance document. It does not replace ISO 9001, ISO/IEC 17025, or your own calibration procedure, and the clause summaries here are plain-language descriptions rather than quotations of the standards. Check any log you build against your own quality system before you use it. Everything runs in your browser and nothing you type is sent anywhere.
Let the due dates chase you
A spreadsheet will never tell you an instrument came due last week. Axiospec tracks every gauge, computes the due dates, and flags what needs recalling, in one place with your certificates and results. Import this log and see it on your own instruments.