How Audit Duration Is Calculated – The Man-Day Factor

Every accreditation body bases its audit schedule on man-days — the number of days assessors need to evaluate your laboratory effectively. Understanding this calculation helps you anticipate both the duration and cost of your assessment.

A man-day simply means one assessor working for one full day. So if your audit involves two assessors for three days, that’s six man-days in total. Accreditation bodies use this measure to determine not only how long the audit will take but also how many experts are required to cover your lab’s scope.

Here’s what usually affects the number of man-days assigned to your lab:

• Size and staffing: More staff means more interviews, records, and documentation to review.

• Scope of testing: The number of test methods and disciplines (e.g., microbiology, hematology, molecular) directly impacts assessment time.

• Locations: Multi-site or collection centers increase logistics and review complexity.

• Accreditation history: New applicants often require longer assessments than labs renewing accreditation.

Typical ranges look like this:

If you want to estimate your own man-days, a simple formula many labs use is:
Base 3 man-days + (0.5 × each additional department) + (0.2 × each remote site)

It’s not official, but it gives a realistic preview of your likely duration.

Pro Tip: Always ask your accreditation body to share the rationale behind their man-day calculation. Reputable bodies will show exactly how they arrived at the number — giving you confidence that both cost and schedule are fair.

With the duration estimated, the next question becomes: how long does the entire process take from start to finish? Let’s look at the complete accreditation timeline.

The Accreditation Timeline – 6 Steps from Decision to Certification

ISO 15189:2022 accreditation follows a predictable path once you understand the stages. Each step builds on the previous one, and skipping ahead usually leads to delays or rework. On average, most labs complete the entire process in 7 to 12 months — depending on resources, readiness, and accreditation body scheduling.

Here’s what that timeline typically looks like:

1. Management Commitment & Project Setup (2–3 weeks)
   Leadership defines goals, allocates resources, and appoints a Quality Manager and implementation team.
2. Gap Analysis & Planning (2–4 weeks)
   The team reviews current practices against ISO 15189:2022 clauses and builds a project plan to close the gaps.
3. Implementation & Documentation (3–6 months)
   The most time-consuming stage — developing or updating SOPs, training staff, calibrating equipment, and generating quality records.
4. Internal Audit & Management Review (1–1.5 months)
   Conduct internal audits across departments, correct any issues, and hold management reviews to confirm system readiness.
5. Application & Pre-Assessment (1–2 months)
   Submit your application to the chosen accreditation body. Assessors review documentation and provide preliminary feedback before the full audit.
6. Final On-Site Assessment & Accreditation Decision (1–2 months)
   Assessors visit your facility, review evidence, and issue findings. Once corrective actions are closed, your accreditation decision is finalized.

Pro Tip: Set internal target dates earlier than your accreditation body’s deadlines. Building a few weeks of flexibility into your schedule helps you stay in control and avoid last-minute stress.

Now that you know the general flow, it’s time to look at a crucial decision that affects your credibility, timeline, and overall experience — choosing the right accreditation body.

Choosing the Right Accreditation Body

Selecting the right accreditation body isn’t just a formality — it’s a strategic decision that influences your lab’s recognition, cost, and long-term success. While every accreditation body follows ISO 15189:2022, their processes, assessor expertise, and responsiveness can differ significantly.

Here’s what to evaluate before making your choice:

• Recognition and credibility – Always confirm that the body is an ILAC MRA signatory. This ensures your accreditation is accepted internationally and adds credibility to your reports.
• Experience in your testing field – Look for assessors who specialize in medical or clinical testing, not just general quality systems.
• Transparency in fees – Ask for a full breakdown of application, man-day, and travel costs. Clarity here prevents unexpected charges later.
• Assessment availability – Check lead times. Some bodies are booked months in advance, so plan accordingly.
• Communication and support – Quick, clear responses are a sign of professionalism. If communication is slow before you apply, it won’t improve afterward.

Here’s a quick snapshot of some recognized accreditation bodies:

Pro Tip: Choose based on credibility and specialization, not price. A well-recognized accreditation body may cost slightly more, but the long-term value in trust and acceptance is worth it.

Once you’ve selected your accreditation body, you’re ready to go through the actual assessment — and later, maintain that recognition through ongoing surveillance. Let’s explore how that works next.

What Happens After Accreditation – Surveillance & Reassessment

Getting your ISO 15189:2022 certificate is a milestone — but it’s not the end of the journey. Accreditation is maintained through a continuous cycle of surveillance visits and reassessments, ensuring your lab stays compliant and competent long after the initial audit.

Here’s how the post-accreditation cycle typically works:

During surveillance visits, assessors focus on how you’re maintaining quality — not just on your documentation. They’ll review internal audit reports, corrective actions, staff competence records, equipment calibration, and EQA participation.

Pro Tip: Keep your system continuously audit-ready. Labs that update records and track actions regularly never need to panic before a visit. It shows assessors that your QMS is active, not reactive.

Maintaining accreditation isn’t about perfection — it’s about consistency. When your lab treats quality management as part of its daily rhythm, surveillance becomes routine, and reassessment is simply another confirmation that your system works.

Now, to bring this process to life, let’s look at one real-world example of how a laboratory navigated the ISO 15189 accreditation journey from start to finish.

Real-World Example – A Mid-Sized Clinical Lab’s Accreditation Journey

A few years ago, I worked with a mid-sized diagnostic laboratory that wanted to achieve ISO 15189 accreditation to expand its contracts with private hospitals. The lab had a solid technical foundation but no formal quality system. Like most teams starting from scratch, they underestimated the time and effort required.

Here’s what made the difference. Instead of jumping straight into documentation, the lab began with a gap analysis and structured the project around clear milestones. They assigned internal leads for each clause, invested in short weekly training sessions, and communicated regularly with their chosen accreditation body, which happened to be ILAC-recognized.

The result? The entire process — from planning to certification — took just under nine months. Their first on-site assessment went smoothly, with only two minor findings that were resolved within two weeks. When their first surveillance visit came a year later, assessors found that all improvements had been sustained, and the lab was already preparing for scope expansion.

This experience reinforced something I’ve seen repeatedly: labs that approach accreditation methodically, with consistent follow-through, save both time and money. The key isn’t rushing the process — it’s staying organized and proactive from start to finish.

Now that you’ve seen how the journey can unfold in practice, let’s answer a few of the most common questions labs ask about ISO 15189 costs, timelines, and the process itself.

FAQs – ISO 15189:2022 Accreditation Cost, Timeline, and Process

1. How much does ISO 15189:2022 accreditation typically cost?
Costs vary depending on your lab’s size, scope, and number of sites. On average, small single-site labs spend around $5,000–$8,000, while larger, multi-department facilities can range from $15,000 to $25,000+. This includes accreditation fees, assessor man-days, and travel — but not internal training or documentation development.

2. How long does the entire process take from start to certification?
For most laboratories, the full process takes between 7 and 12 months. Smaller, well-prepared labs may finish sooner, while larger or newly established labs often need extra time for documentation and system stabilization.

3. What are the main factors that influence the timeline?
Your readiness, staff engagement, documentation quality, and accreditation body’s scheduling capacity all matter. The more organized and responsive your team is, the faster the process moves.

4. Can we reduce the overall cost or duration?
Yes — focus on narrowing your initial scope of accreditation to your core services, and expand later. Using a digital QMS also helps manage records efficiently and reduces the risk of rework or lost documentation.

5. What happens after we receive our accreditation?
You’ll enter a three-year maintenance cycle, with annual surveillance visits to confirm compliance. As long as you keep your system active — closing findings, training staff, and maintaining equipment — the process becomes routine rather than stressful.

Now that we’ve addressed the key questions, let’s wrap up this guide with one final thought on how to approach accreditation strategically — not just successfully.

Plan Early, Budget Wisely, Stay Consistent

ISO 15189:2022 accreditation is one of the most powerful ways a laboratory can demonstrate technical competence and reliability — but it’s also a project that demands structure, patience, and foresight. The labs that achieve it smoothly aren’t necessarily the biggest or best-funded; they’re the ones that plan carefully, budget realistically, and stay consistent through every stage.

The process isn’t as overwhelming as it seems once you understand its rhythm. You start with commitment, build your system step by step, prepare your team, and collaborate closely with your chosen accreditation body. From cost planning to surveillance visits, each phase reinforces your credibility and sharpens your performance.

After helping numerous laboratories navigate ISO 15189:2022 accreditation, one thing stands out every time — success comes down to clarity and consistency. When you know what’s coming, you can prepare intelligently, respond confidently, and maintain compliance effortlessly.

If you’re ready to plan your journey, use our ISO 15189 Cost & Timeline Planner — it’s designed to help you estimate expenses, set milestones, and manage your project from day one to accreditation day.

Because the more intentional your preparation, the faster you’ll move from planning to certification — and the stronger your laboratory will stand in the years that follow.

Melissa Lazaro

Melissa Lavaro is a seasoned ISO consultant and an enthusiastic advocate for quality management standards. With a rich experience in conducting audits and providing consultancy services, Melissa specializes in helping organizations implement and adapt to ISO standards. Her passion for quality management is evident in her hands-on approach and deep understanding of the regulatory frameworks. Melissa’s expertise and energetic commitment make her a sought-after consultant, dedicated to elevating organizational compliance and performance through practical, insightful guidance.