A Calibration Register That Works Out Its Own Due Dates
A register of every gauge and measuring instrument in your shop: what it is, how often it must be calibrated, when it last was, and when it is next due. Overdue instruments rise to the top of the list on their own, under a red line that says how many need attention.
Switched on for your company on request. Contact us to use it
How to use it
Add each instrument with its number, what it is, its specification and how often it must be calibrated, in days. Enter the date it was last calibrated from your current register; that becomes its first record. Each time it is calibrated, add a record: for a check done in-house, the GO and NO GO readings, who checked it and which master gauge was used; for a calibration done by a lab, the lab's name and its certificate as a file. The register works out the next due date from the last record and the frequency, and keeps every record, so an instrument's whole history is on one page.
An example register
Seven gauges in a small turning shop, as the register reads on the date in the table's heading below. The status, the next due date and the order of the rows are worked out by the same calculation MechCircle runs on a real register; nothing below was typed in by hand. The register's red line for this example reads: “1 overdue · 1 never calibrated · 1 due within 30 days — calibrate before use.” The dial bore gauge G-11 is marked missing, so it is left out of the list by default: a missing or scrapped instrument keeps its history, but is never due for anything.
Example register, as it reads on 12/Oct/2026
| No. | Instrument | Specification | Every | Last calibrated | By | Next due | Status |
|---|---|---|---|---|---|---|---|
| G-3 | Plug gauge | Ø8 H7, GO / NO GO | 90 days | 20/Jun/2026 | In-house | 18/Sep/2026 | Overdue by 24 days |
| G-5 | Height gauge | 0–300 mm | 365 days | — | — | — | Never calibrated — due now |
| G-2 | Outside micrometer | 0–25 mm, 0.001 | 365 days | 30/Oct/2025 | External (lab) | 30/Oct/2026 | Due in 18 days |
| G-1 | Digital vernier caliper | 0–150 mm, 0.01 | 182 days | 02/Jun/2026 | External (lab) | 01/Dec/2026 | 50 days left |
| G-4 | Thread ring gauge | M10×1.5 6g, GO / NO GO | 365 days | 15/Mar/2026 | External (lab) | 15/Mar/2027 | 154 days left |
| G-10 | Edge finder | Ø10 mm, for setting only | — | — | — | — | Not calibrated |
What each column means
- No.
- Your own number for the instrument, sorted the way a person counts: G-4 comes before G-10, where a plain alphabetical sort would put G-10 first. A number is optional: some shops do not number a weighing scale.
- Instrument and Specification
- What it is, and its range and least count, or the size and fit it checks.
- Every
- How often it must be calibrated, in days. Left blank, the instrument has no calibration regime and reads “Not calibrated”, never “overdue”: right for something like the edge finder G-10, used for setting a job and never to accept a part.
- Last calibrated
- The date of its most recent calibration record, taken from the records themselves.
- By
- In-house, checked against your own master gauge, or External, by a calibration lab.
- Next due
- The last calibration plus the frequency, worked out every time the register is opened.
- Status
- Overdue by so many days, never calibrated, due within 30 days, or days left. Overdue and never-calibrated instruments are listed first.
Why the due date is never typed in
On a spreadsheet register the next due date usually sits in its own column, typed by hand, and sooner or later it stops matching the calibration it was meant to follow. Here there is no such column. The next due date is worked out from the latest calibration record and the frequency, so correcting a record corrects the due date with it, and the register cannot say a gauge is in date when its records say otherwise.
What an auditor looks for (ISO 9001:2015, clause 7.1.5.2)
- Every instrument used to accept parts can be identified: its own number, and what it is.
- It is calibrated or verified at a stated interval against measurement standards traceable to national or international standards, or, where none exist, the basis used is recorded.
- Its calibration status can be seen, so nobody measures with an overdue gauge.
- Each calibration is recorded: when, by whom, the result, and the certificate.
- When an instrument is found out of calibration, someone checks whether parts already measured with it are affected, and acts on it.
How it helps
- Overdue gauges are visible the moment the register opens, not when an auditor finds them
- One page per instrument, with every calibration it has had and its certificates
- A missing or scrapped instrument keeps its history but stops asking to be calibrated
- Nobody has to keep a due-date column in step by hand
What it does and does not cover
- It does not calibrate anything or check a certificate. Traceability is whatever your lab's certificate states; the register keeps the certificate as a file.
- It does not email a reminder before an instrument falls due. Overdue and due-soon instruments show in the register itself.
- It does not record which gauge measured which lot. An inspection format can name the gauge for each dimension, and the printed sheet carries it, but readings are written on the sheet, not stored, and an instrument's page does not list the formats that use it.
- A Not OK result does not take the instrument out of use on its own. Marking it scrapped or missing is a deliberate step, and deciding what the result means for parts already measured is a person's decision.
- No measurement system analysis: no gauge R&R and no uncertainty calculation.
- Intervals are counted in days from the last calibration. It does not follow a calendar rule such as “every March”.
- There is no spreadsheet import yet. Each instrument is added once, with the date it was last calibrated.
Good to know
Do I have to enter every past calibration?
No. Add each instrument with the date it was last calibrated; that is enough for the register to work out when it is next due. Older records can be added later if you want the full history in one place.
Can a gauge be tied to the part it checks?
Yes. An instrument can name the part it is made for, and can be marked as supplied by a customer.
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