What is on-the-wall calibration?

On-the-wall calibration is a practical way to perform accredited or traceable calibration directly where devices are installed without spare equipment or external parties interrupting the operation.

In short, on-the-wall calibration is a method where, instead of removing loggers for off-site calibration or inviting technicians to pause operations, the data logger is calibrated directly “on the wall” (or “on the shelf”), using external sensors. This keeps monitoring active and alarms in place, while automatically generating traceable certificates.

Learn more about temperature calibration guidelines and best practices in GxP.

How does on-the-wall calibration work?

On-the-wall calibration is a digital evolution of in-situ calibration. The technology-enabled method uses external, replaceable sensor tips together with automated calibration notifications and digital calibration certificates, ensuring calibration can be performed without removing devices while keeping records audit-ready.

The on-the-wall calibration process works like this:

• Get notified: The system alerts when a device is due for calibration.
• Collect sensor tip: The user receives newly calibrated replaceable sensors for each applicable data logger.
• Swap sensor: The team replaces the old sensor tip with the calibrated one. This can often be done in only seconds per device.
• Confirm readings: A check is performed to make sure the device stabilizes within acceptance limits.
• Automatic documentation: The calibration is automatically registered in the system, and the digital calibration certificates are linked to the data logger record, making it possible to get a full overview of data across calibrations.
• Close task: Calibration is marked complete, and Quality signs off.

How does on-the-wall calibration fit into GxP?

GDP, GMP, and similar GxP](/regulations-temperature-compliance/gxp) guidelines require calibrated, traceable, well-documented equipment.

On-the-wall calibration supports these requirements by providing accredited or traceable calibration in a format that does not disrupt the operation and minimizes risks of calibration errors or oversight through automatic notifications and documentation.

Examples:

• GDP (Good Distribution Practice, EU 2013/C 343/01): Warehouses, transport units, and logistics depots must use calibrated monitoring devices to safeguard product quality during storage and shipping.
• GMP (Good Manufacturing Practice, Annex 15): Labs, cleanrooms, and production areas rely on calibrated instruments for reliable test results and product release decisions.

Key compliance requirements that on-the-wall calibration supports

• ISO/IEC 17025: Accredited calibration certificates must state uncertainty and traceability to SI units.
• ILAC P14: Requires measurement uncertainty reported on every certificate, which is included automatically.
• ILAC G24: Intervals are set and justified on a risk basis, with evidence from performance data.
• GDP and GMP: Both require calibrated monitoring equipment with full documentation.
• Annex 11 and Part 11: Digital records include secure audit trails, role-based access, and validated systems for data integrity.

Also read: Guidelines for temperature mapping for GxP

What are the benefits of on-the-wall calibration?

Traditional calibration methods often create trade-offs between compliance, cost, and continuity of operations. The on-the-wall calibration method minimizes these trade-offs by enabling calibration at the point of use, supported by digital certificates and automated reminders.

This section outlines the key benefits in context with GxP expectations.

Some of the main benefits of the method are:

• No downtime: Devices remain mounted and alarms stay active during calibration. This avoids disruptions in GMP cleanrooms, labs, and GDP warehouses.
• No need for spare loggers: Because the calibration is performed directly at location, there is no need to maintain or manage extra data loggers.
• Automatic documentation: Digital calibration certificates are generated instantly, including traceability to SI units and measurement uncertainty per ISO/IEC 17025 and ILAC P14.
• Risk-based intervals: Intervals can be set and adjusted according to ILAC G24 guidance, supported by performance data, rather than relying on fixed calendar schedules.
• Simplified audits: Certificates, as-found/as-left data, and audit trails are stored digitally in systems designed for Annex 11 and 21 CFR Part 11 compliance, making audits faster and more transparent.
• Global harmonization: The method can be standardized across multiple facilities and countries, helping global pharma and biotech companies implement consistent SOPs for calibration.
• Reduced operational costs: Lower labor requirements, fewer spare devices, and reduced logistics compared to off-site calibration translate into measurable savings.

Where is on-the-wall calibration relevant?

On-the-wall calibration is particularly valuable in industries where downtime is costly, operations are continuous, and compliance demands are strict. This is, for instance:

• Pharmaceutical manufacturing (GMP): Used in QC labs, cleanrooms, and production lines to maintain calibration without halting critical processes.
• Biotech: Supports sensitive laboratory environments where interruptions compromise data integrity.
• Pharmaceutical logistics (GDP): Applied in warehouses, cold chain storage, and transport units to ensure calibrated monitoring devices protect medicinal products.
• Healthcare and hospitals: Helps labs and pharmacies maintain compliance without disrupting patient-critical environments.
• Global supply chains: Fits multinational operations where harmonized calibration processes are needed across multiple sites.

Also read: Certifications and accreditations

How can you implement on-the-wall calibration?

Rolling out on-the-wall calibration requires embedding the method into existing GxP processes. Teams should consider both regulatory anchors and operational realities.

1. Plan: Define calibration intervals using ILAC G24 guidance, specify acceptance criteria, and decide when ISO/IEC 17025 accreditation is required versus when traceable calibration is sufficient. Develop a risk assessment to justify the choice.
2. Deploy: Train local teams on the calibration workflow, ensure sensors are labeled and linked to assets, and verify that certificates capture uncertainty per ILAC P14. Integrate these certificates into the quality management system.
3. Operate: Monitor drift trends over time, adjust intervals with evidence, and prepare digital audit packs with certificates, traceability, and as-found/as-left data. Maintain oversight through a central dashboard that covers all GMP and GDP sites.

This way, the method becomes a repeatable process that works across multiple facilities and satisfies both auditors and daily operations.

What are the risks of on-the-wall calibration?

Any new quality process is only as good as the effort that goes into implementing it right – and, although on-the-wall calibration will reduce both risks, downtime, and costs significantly in most use cases, it – as any method – requires proper governance.

Here are 5 key risks you should consider when implementing on-the-wall calibration:

• Operational discipline: Certificates must be linked to the correct assets. Without controlled processes, mismatches can weaken traceability.
• Interval justification: Risk-based intervals must be documented and defended. Without ILAC G24-based rationale, auditors may challenge the program.
• Data integrity controls: Even with digital certificates, systems must be validated and protected with audit trails, access roles, and backups.
• Change management: Staff must be trained and SOPs updated. Poor adoption can lead to inconsistent execution across sites.
• Critical environments: In ultra-critical GMP contexts, portable reference standards must meet required uncertainty levels. Without verification, extra justification may be needed.

By embedding these controls, quality teams can ensure on-the-wall calibration consistently meets GDP and GMP expectations while minimizing compliance risk.