Calibration
Equipment Calibration Log Template: What to Record (Free Template)
Every accredited lab keeps a calibration log. Most of them are missing at least one field an assessor will ask about — usually the one that turns “we calibrated it” into “we can prove the calibration was valid.” This post gives you a complete, copy-ready template, explains why each field is there, and covers the three signals that you’ve outgrown the spreadsheet it lives in.
What a calibration log actually has to prove
A calibration log is not a diary of visits. Under ISO 15189, CAP, and CLIA alike, it has to answer four questions for any instrument, at any point in its history:
- Was the instrument calibrated on schedule? — dates and the interval rationale.
- Did it pass? — a defensible result, not just a tick.
- Who did the work, and with what? — the technician or provider, and the reference standard used.
- What happened when it failed? — the actions taken before the instrument returned to service.
Most homemade logs handle question 1 and half of question 2. Questions 3 and 4 are where audit findings live.
The template
One row per calibration event. Copy this structure into your register:
| Field | Example | Why auditors ask for it |
|---|---|---|
| Equipment ID / internal code | BAL-004 | Ties the event to one physical instrument, not a model |
| Equipment name & serial no. | Sartorius MSE225P, s/n 0034 | Survives relabelling and asset renumbering |
| Calibration track | Annual external / monthly verification | Instruments often carry more than one schedule |
| Date performed | 2026-06-14 | The compliance event itself |
| Performed by | J. Osei (or vendor name) | Competency traceability |
| Reference standard used | Cert. E2 weight set, cert #4411 | Metrological traceability — the most-skipped field |
| As-found readings | 199.94 mg @ 200 mg point | Whether the instrument was in spec before adjustment |
| As-left readings | 200.01 mg | The state it returned to service in |
| Tolerance | ± 0.10 mg | Makes pass/fail objective instead of a judgement call |
| Result | Pass / Fail / Adjusted | The verdict, per measurement point if possible |
| Next due date | 2027-06-14 | Derived from the passing event, not typed by hand |
| Certificate reference | CAL-2026-0113 | Links the log row to the evidence document |
| Actions on failure | Removed from service; repeat after service visit | Question 4 — the field failure investigations depend on |
Rules that keep the log defensible
A failed calibration must not advance the due date. If the instrument failed on 14 June, the schedule stays overdue until a passing calibration is logged. Spreadsheets get this wrong constantly, because the “next due” cell is a formula off the last date — any date.
The log and the certificate must agree. If the certificate says three measurement points and the log says “pass,” an assessor will ask which one is the record. Reference the certificate number in the log row and store the file where it can be produced in seconds.
Record the failure path, not just the failure. “Fail” with an empty actions column is a finding waiting to be written. Even one line — removed from service, repeat calibration scheduled — closes the loop.
One instrument can carry several tracks. An analytical balance with an annual external calibration and a monthly internal verification needs both visible, each with its own due date. Merging them into one column guarantees one of them silently lapses.
Three signs you’ve outgrown the spreadsheet
The template above works on paper or in Excel — up to a point. These are the signs you’ve passed it:
- Nobody is watching the due dates. A log records history; it doesn’t chase people. Once you have more than a couple of dozen instruments, “check the spreadsheet weekly” fails quietly, and you find out via an overdue instrument during an inspection.
- The evidence lives somewhere else. If certificates are in a shared drive, readings are in the log, and failure actions are in email, assembling one instrument’s history for an assessor takes an afternoon instead of a click.
- More than one person edits it. Concurrent edits, deleted rows, overwritten formulas — a spreadsheet has no audit trail, and a compliance record without an audit trail is a soft target for any assessor who has seen one tampered with before.
Frequently asked
How long should calibration records be retained? At minimum two years under CLIA; ISO 15189 and CAP expect retention consistent with your document-control policy, and many labs keep the full instrument lifetime plus two years. Keep records for retired instruments — look-back investigations don’t care that the instrument is gone.
Do I need a separate log per instrument? No — one register with one row per event is easier to audit, as long as it filters cleanly by instrument. What you do need is per-instrument visibility of all its tracks and its complete history.
Is a vendor’s certificate enough on its own? No. The certificate is evidence for one event. The log is the continuity record proving the schedule was maintained across years. You need both, cross-referenced.
