Pipettes touch nearly every quantitative result in a lab, and they drift quietly. A worn seal or a bent piston doesn't announce itself; it just shifts every volume a little. That is why pipette calibration is one of the first things a CAP or CLIA surveyor checks, and why the question we hear most is how often it needs to be done.
The short answer
Most labs calibrate pipettes every 6 to 12 months, and every 3 to 6 months for pipettes that are heavily used or critical to patient results. There is no single number written into CLIA for pipettes. What surveyors expect is a defined interval, based on the manufacturer's guidance and your own risk, that you actually follow.
- Every 3–6 months: high-use pipettes, molecular and PCR setup, IVF and micro-volume work, and any pipette used for calibrators or controls
- Every 6–12 months: routine clinical and histology pipettes with moderate use
- At least annually: low-use pipettes still in service
When to calibrate early
Some events should send a pipette for calibration regardless of its due date:
- It was dropped, or the tip cone or shaft is visibly damaged
- It was repaired, or seals or pistons were replaced
- It drips, leaks or holds liquid in the tip
- QC results shift and the pipette is a possible cause
- It is new, or coming back from loan or storage
What a proper calibration checks
The accepted method is gravimetric: dispense water at set volumes, weigh each dispense on a calibrated analytical balance, and convert the weight to volume with corrections for temperature and air pressure. The reference standard is ISO 8655.
- Accuracy (systematic error): how close the average volume is to the set volume
- Precision (random error, often shown as CV): how consistent repeated dispenses are
- Multiple test volumes across the range, usually the minimum, middle and maximum
- Every channel of a multichannel pipette, reported individually rather than averaged
- As-found and as-left results, so you can see whether a pipette was out of tolerance before adjustment
That as-found result matters. If a pipette was out of tolerance when it arrived, your lab may need to review the results it was used for since its last good calibration.
Between calibrations
Many labs add a quick in-house check between professional calibrations, especially for critical pipettes: a few gravimetric dispenses on the lab's own balance, logged monthly or quarterly. It catches a failing pipette weeks earlier and gives surveyors evidence that you are watching.
What surveyors want to see
- A written calibration interval for each pipette, or each pipette type
- Certificates with as-found and as-left data and traceability to NIST
- A dated label on each pipette that matches its certificate
- A record of what you did when a pipette failed
If you'd rather not track it yourself, our pipette calibration service sets the interval, calibrates on-site or by mail-in, and keeps every certificate on one due-date list. Calibration is available starting from $25 per single-channel pipette. For other instruments, see how often to calibrate lab equipment.