Instrument Calibration Logging Hub — Free Calibration Due Tracker

This tool logs instrument calibrations and tracks due dates. You list each instrument with its last calibration date and its calibration interval in days, and the tool computes the next due date and flags each instrument as OK, due soon (within 14 days), or overdue. Calibration is the unglamorous backbone of measurement: an uncalibrated balance, thermometer, or pipette produces numbers that look precise and are quietly wrong, and every result downstream inherits the error. A visible due list turns calibration from a memory task into a checklist.

How to use it

List instruments, one per line: Name, last date, interval days.
Optionally set today (otherwise real today is used).
Click Check calibration status.
Book calibration for due-soon and overdue instruments.
Update the last date after each calibration.

Worked example

Balance A was last calibrated 2026-09-01 with a 90-day interval, so its due date is 2026-11-30 — OK on 2026-10-25. Thermometer B was last calibrated 2026-10-10 with a 28-day interval, due 2026-11-07 — due soon, with 13 days left, so the lab books its calibration now rather than discovering it overdue mid-experiment. The worked example shows the tool’s real function: not the arithmetic, which is trivial, but the flag, which arrives early enough to act on.

Honest limits

The tool tracks dates only: it does not store calibration certificates, as-found/as-left values, or uncertainty budgets, and it cannot verify that a calibration actually happened — it trusts the dates you type. The 14-day due-soon window is a fixed rule, not a lab policy; labs with long booking lead times should treat “due soon” as “book now” and set their own earlier trigger. Intervals must come from the instrument manual or lab procedure, not from this tool, which performs no metrology judgement.

Who it is for

This tool is for lab managers tracking a bench of instruments, students learning why calibration schedules exist, and small labs without a dedicated asset system. It is a due-date tracker, not a calibration record system.

Going further

Pair the due list with a rule: no instrument past due is used for reportable data, full stop, and the rule is enforced by removing overdue instruments from the bench, not by trusting memory. The cost of recalibrating early is trivial next to the cost of repeating an experiment because its measurements were taken on an overdue instrument. Keep the calibration certificates beside this list — the dates here tell you when, the certificates tell you what was found — and when an instrument repeatedly drifts out of tolerance before its interval ends, shorten the interval: the schedule should follow the instrument’s behaviour, not the manufacturer’s default. Review the calibration list at the same meeting where experiments are planned, not after they are done. A due date discovered during planning costs a booking; a due date discovered during analysis costs the experiment. Put the list on the agenda monthly, assign one owner per instrument, and treat an overdue flag as a stop signal that nobody overrides quietly: if the work cannot wait, document the exception, the reason, and the risk accepted, so the decision is visible rather than hidden. Labs that treat calibration as paperwork fail quietly, one uncalibrated measurement at a time; labs that treat it as a gate fail loudly, once, at planning, and then fix it. The difference is not effort but timing. When an instrument returns from calibration, record both the as-found and as-left values if the certificate provides them, because the as-found value reveals how far the instrument had drifted since its last calibration and whether any data taken just before the due date should be reviewed.

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