Accreditation for Calibration Laboratories

Measurement disciplines

Calibration scopes are defined by measurement discipline, parameter, range, and best measurement capability (CMC). Principal disciplines include:

Discipline	Parameters	Typical reference standards
Dimensional	Length, angle, flatness, roughness	Gauge blocks, interferometers, CMMs
Mass & force	Mass, force, torque, hardness	OIML E1/E2 weights, deadweight machines
Pressure & vacuum	Absolute, gauge, differential pressure	Piston gauges, capacitance manometers
Temperature & humidity	Contact & non-contact temperature, RH	Fixed-point cells, SPRTs, chilled-mirror hygrometers
Electrical	DC/AC voltage, current, resistance, capacitance, frequency	Josephson arrays, quantum Hall, Cs standards
Time & frequency	Frequency, time interval, phase noise	Atomic clocks, GPS-disciplined oscillators
Flow & volume	Liquid flow, gas flow, volume	Gravimetric systems, bell provers
Optical & radiometric	Luminous intensity, wavelength, optical power	Trap detectors, spectroradiometers

Core requirements

Calibration laboratories must meet all ISO/IEC 17025:2017 requirements, with particular emphasis on metrological traceability and measurement uncertainty:

Metrological traceability — Unbroken chain to SI units through national metrology institutes (NMIs) or designated institutes (Clause 6.5)
Measurement uncertainty — GUM-compliant uncertainty budgets for every calibration procedure in scope (Clause 7.6)
Best measurement capability (CMC) — Smallest uncertainty achievable under routine conditions, expressed at 95% confidence (k = 2)
Environmental controls — Temperature, humidity, and vibration controlled and monitored per procedure requirements (Clause 6.3)
Equipment management — Calibration intervals, drift studies, and intermediate checks for all reference standards (Clause 6.4)
Calibration certificates — Compliant with ISO/IEC 17025 Clause 7.8 including uncertainty statements and traceability declarations

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Key metrics

Cycle: 4-year accreditation period
Surveillance: Annual on-site assessments
ILC/PT: Required per discipline per year
Assessment team: 1 Lead + 1–2 Technical Assessors
Decision timeline: ≤ 30 days after assessment report

Required documentation

Document	Description	ISO Ref.
Quality manual	Policies, organizational chart, scope statement, quality objectives	Clause 8.2
Calibration procedures	Step-by-step procedures for each parameter and range in scope	Clause 7.2
Uncertainty budgets	GUM-compliant evaluation for each calibration procedure	Clause 7.6
Traceability evidence	Certificates from NMIs or accredited laboratories for all reference standards	Clause 6.5
Equipment list	Reference standards, working standards, calibration intervals, drift data	Clause 6.4
Personnel records	CVs, qualifications, competency assessments, and authorization logs	Clause 6.2
Environmental monitoring	Temperature/humidity logs, control limits, and excursion protocols	Clause 6.3
PT/ILC results	Proficiency testing and inter-laboratory comparison records (last 2 cycles)	Clause 7.7
Internal audit reports	Most recent internal audit cycle with findings and corrective actions	Clause 8.8
Impartiality declaration	Conflict-of-interest risk assessment and signed declarations	Clause 4.1

Traceability & CMC requirements

Metrological traceability is the foundation of calibration accreditation. IAC requires:

Reference standards calibrated by an NMI, BIPM, or an ISO/IEC 17025-accredited laboratory
Complete traceability chain documentation from working standard to SI unit
CMC values published on the IAC scope certificate—verified during each assessment
Drift studies and stability records for all primary and secondary reference standards
Intermediate checks between calibration intervals to confirm reference standard integrity

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Assessor qualifications

Technical assessors for calibration programs must demonstrate:

Degree in metrology, physics, or engineering
Minimum 5 years of calibration laboratory experience
Expertise in the specific measurement discipline assessed
Completed IAC Lead Assessor training (40 hours)
Current knowledge of GUM and ISO/IEC 17025:2017

Assessment process

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1. Document review

Uncertainty budgets, traceability evidence, and procedures are reviewed against ISO/IEC 17025 requirements. A document review report is issued within 4 weeks.

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2. On-site assessment

2–4 day assessment covering facilities, environmental controls, reference standards, personnel interviews, and witness calibrations. Nonconformities are classified as Major or Minor.

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3. Corrective action

Major nonconformities: 90-day resolution window. Minor: 60 days. Evidence is reviewed by the lead assessor before case closure.

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4. Accreditation decision

The Accreditation Committee reviews the full case independently. CMC values are confirmed and published on the certificate of accreditation.

Fees and timelines

Application fee: USD 2,500 (non-refundable)
Document review: USD 3,000–4,500
On-site assessment: USD 1,800/day × assessor days
Annual surveillance: USD 2,000–3,500
Scope extension: USD 1,500 per additional discipline

Typical timeline: 12–18 weeks from complete application to accreditation decision.

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Get a quote

Fees depend on the number of measurement disciplines, parameters, and locations. Contact us for a personalized estimate.

Full fee schedule → Request a quote →

Frequently asked questions

Do mobile calibration services qualify for accreditation?

Yes. Mobile (on-site) calibration services can be accredited provided the laboratory demonstrates that procedures, equipment control, environmental monitoring, and competency requirements are met at customer locations. Mobile scope is explicitly listed on the accreditation certificate.

Can CMC values be updated after initial accreditation?

Yes. Improvements in CMC (lower uncertainties) can be claimed at any surveillance assessment by presenting updated uncertainty budgets and supporting evidence. CMC increases (higher uncertainties) are processed as scope reductions.

What if formal PT programs are unavailable for our discipline?

Where accredited PT programs (ISO/IEC 17043) are not available, IAC accepts bilateral inter-laboratory comparisons (ILCs) with a national metrology institute or another accredited calibration laboratory. The ILC plan must be approved by IAC in advance.

How does IAC handle metrological traceability to non-SI quantities?

For quantities outside the SI system (e.g., pH, hardness scales), traceability is established to internationally agreed reference values, consensus standards, or specified methods per ISO/IEC 17025 Clause 6.5 and ILAC P-10.

Can we calibrate equipment that we also sell or manufacture?

Yes, but this creates an impartiality risk that must be identified, assessed, and mitigated in your risk register. IAC assessors will verify that commercial interests do not influence calibration results. Additional safeguards (e.g., separated staff, blind reviews) may be required.

Is accreditation recognized internationally?

IAC is working toward mutual recognition through ILAC MRA participation. Accredited calibration certificates issued under IAC are designed to be consistent with international requirements, facilitating acceptance across borders.