Humidity & Temperature Calibration Services

Humidity calibration is the process of verifying and adjusting a humidity sensor or probe’s accuracy by comparing its output to NIST-traceable reference standards at two or more known relative humidity values, and documenting the results with calibration certificates. Calibration establishes the as-found error at each calibration point, determines whether the sensor is within its manufacturer-specified accuracy limits, and documents the as-left performance after any corrections are applied. For regulated laboratories, a calibration certificate with NIST-traceable reference documentation provides the legal evidence of humidity measurement accuracy required by GMP, FDA, CAP, CLIA, and ISO programs for controlled storage monitoring, stability testing, and environmental monitoring applications.

Humidity probe and sensor calibration frequency depends on the laboratory type, regulatory requirements, and criticality of the monitored environment. Pharmaceutical facilities under cGMP typically calibrate humidity sensors every 6–12 months, with calibration intervals defined in the sensor’s qualification plan and environmental monitoring SOP. Clinical laboratories under CAP or CLIA typically calibrate annually at minimum, with more frequent calibration for sensors monitoring critical storage areas. Research and general laboratory sensors should be calibrated annually. All humidity sensors should be recalibrated after physical relocation, after any repair or sensor replacement, or when trending data shows performance drift outside established acceptance criteria. Calibration intervals should be documented in the laboratory’s quality system.

Measurement uncertainty for humidity calibration is a quantitative statement of the doubt associated with a humidity measurement result, expressed as an expanded uncertainty (U) at a specified coverage factor (typically k=2, corresponding to approximately 95% confidence level). For humidity calibration, expanded uncertainty values typically range from ±0.5 % RH to ±2 % RH depending on the reference standard used, the calibration points, and the calibration method. ISO/IEC 17025 accredited calibration laboratories are required to evaluate and report measurement uncertainty on every accredited calibration certificate. A documented uncertainty statement is essential for determining whether a sensor’s as-found error is within specification with the required level of statistical confidence — and is increasingly required by FDA inspectors and CAP surveyors reviewing calibration records for controlled environment monitoring systems.

Yes. Femto Scientific provides onsite humidity and temperature sensor calibration across major U.S. laboratory markets including New York, New Jersey, Boston, Philadelphia, Baltimore, Connecticut, California, Texas, and many more. Onsite service is ideal for laboratories with large fleets of humidity probes and data loggers, for GMP facilities requiring witnessed calibration or complete environmental monitoring system calibration, and for fixed installation sensors in cleanrooms, cold rooms, and stability chambers that cannot be easily removed. For laboratories outside our direct service territory, we offer depot calibration at our ISO 17025 accredited laboratory in Somerset, NJ. Contact us to confirm scheduling availability in your location.

While ISO 17025 accreditation is not explicitly required by name in every regulatory framework, it is the recognized standard for demonstrating technical calibration competence for environmental monitoring instruments and is increasingly expected by FDA, CAP, and CLIA auditors. The key practical difference between ISO 17025 accredited humidity calibration and non-accredited calibration is the documented measurement uncertainty statement on the certificate. Without a measurement uncertainty statement, it is not possible to determine whether a sensor’s error is within its acceptance criteria with the required level of statistical confidence — a limitation that FDA inspectors and CAP surveyors are increasingly scrutinizing in environmental monitoring programs. Femto Scientific’s Level 3 and Level 4 calibration certificates include all elements required for ISO 17025 compliance, including documented expanded measurement uncertainty and full reference standard traceability documentation.