How to choose a temperature data logger for mapping and monitoring
Match resolution and accuracy to the acceptance criteria, check the calibration offer, and look at memory, battery, export format and response time before price.
Specification checklist
- Range: covers the application with margin (a −80 °C freezer needs a probe rated well below −80 °C).
- Resolution: 0.01 °C for calibration-grade work; 0.1 °C is often the limiting uncertainty term.
- Accuracy specification and — separately — the calibration uncertainty the supplier can actually certify.
- Sampling interval range and memory for the study duration at that interval.
- Battery life at the interval and temperature of use.
- Response time; internal vs external probe.
- Time-stamping, clock accuracy and synchronisation between loggers.
- Export: CSV or equivalent with timestamps, values and units explicit; audit trail if used for monitoring.
- Physical: ingress rating, mounting, size for the positions planned.
For mapping studies, uniformity between loggers matters more than absolute accuracy of any one: calibrate them together against the same reference.
Frequently asked questions
- Is a manufacturer's 'factory calibration' enough?
- Only if it comes with a certificate from an accredited laboratory stating uncertainty and traceability. A 'calibrated' sticker with no certificate is not evidence.
- How many loggers should be bought for mapping?
- Enough for the largest space plus spares — typically 10–20 % extra to cover failures and post-study checks.
References
- [1]WHO Technical Supplement 16 to TRS 961 Annex 9: Environmental temperature monitoring systems for fixed storage areas
- [2]ISO/IEC 17025:2017 — General requirements for the competence of testing and calibration laboratories
General technical guidance written against the cited sources. It is not regulatory or legal advice and does not replace the applicable standard, guideline or a qualified reviewer's judgement.
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