ISO 13849-1 vs IEC 62061: Choosing the Right Functional Safety Standard for Your Machine

Document version: 1.0 | Fact-checked: August 2026 | Standards status verified against ISO, IEC, European Commission and certification-body sources.

Executive summary

• ISO 13849-1 (current edition ISO 13849-1:2023, EN ISO 13849-1:2023) rates the reliability of safety-related parts of control systems (SRP/CS) using Performance Levels (PL a–e). It is technology-neutral: electrical, electronic, hydraulic, pneumatic and mechanical control systems all qualify.
• IEC 62061 (current edition IEC 62061:2021, EN IEC 62061:2021, with amendments A1:2024 and A2:2026) rates safety-related control systems (SCS) using Safety Integrity Levels (SIL 1–3), the machinery-sector adaptation of the IEC 61508 approach.
• The two standards were deliberately aligned in their 2023/2021 editions: they now share identical PFHd targets, comparable architectures and harmonized software requirements, and cross-use of components designed to one standard is explicitly permitted.
• PL ↔ SIL correspondence (informative): PL b/c ≈ SIL CL 1, PL d ≈ SIL CL 2, PL e ≈ SIL CL 3. PL a has no SIL equivalent.
• Bottom line for machine builders: if your Type-C (product) standard or customer specification names one route, use it. Otherwise choose ISO 13849-1 for electro-mechanical / pneumatic / hydraulic safety circuits and IEC 62061 for programmable electronic systems with complex software. A single design can usually be documented under both.

1. What each standard is

Historical note. The 2005 edition of IEC 62061 covered only electrical/electronic/programmable-electronic systems (SRECS); ISO 13849-1 traditionally covered everything else. The 2021 edition removed that technology boundary, which is why the two standards now overlap almost completely in scope. A merger project (ISO 17305) was abandoned, and the revision committees instead harmonized the two documents clause by clause.

2. The two rating systems: PL and SIL

Both standards ultimately quantify the same thing: the average frequency of a dangerous failure per hour (PFHd) that the safety function may exhibit. The PFHd target ranges are identical in both documents.

2.1 PL ↔ SIL ↔ PFHd correspondence table

SIL ranges per IEC 61508: SIL 1 = ≥ 10⁻⁶ to < 10⁻⁵; SIL 2 = ≥ 10⁻⁷ to < 10⁻⁶; SIL 3 = ≥ 10⁻⁸ to < 10⁻⁷ (1/h). The PL–SIL correspondence is informative, not a substitution rule — a PL is a performance range, a SIL is an integrity claim limit. Never mix verification methods mid-project.

2.2 How each standard achieves the target

Category ⇄ architecture correspondence (informative):

3. Risk assessment: how the required level is determined

Both standards start from a risk assessment according to EN ISO 12100 (risk reduction process: risk analysis → risk evaluation → risk reduction). The difference is the parameter set used to derive the required level.

4. Strengths and limitations

5. Typical applications and industry preferences

Always check the applicable Type-C standard first: many product standards prescribe which functional-safety route to take (and at what level). When a Type-C standard is silent, either B-standard is acceptable.

6. Decision guidance and dual-compliance strategy

Which standard should you use?

Choose ISO 13849-1 when… - Your safety functions are implemented with relays, contactors, pneumatic/hydraulic valves or simple electronics. - A Type-C standard or customer specification references PL / Category. - Your team is new to functional safety — the PL route is the gentler entry point. - You want free tooling (SISTEMA) and abundant component MTTFd/DC data.

Choose IEC 62061 when… - The safety function is executed by programmable electronic systems (safety PLCs, drives, networks) with substantial software. - Your supply chain publishes SIL/PFHd data (drives, safety controllers). - Customers or integrators demand an IEC 61508-heritage approach, SRS documentation and verification independence. - You operate in sectors where SIL language is the norm.

Both standards, one design (dual compliance) — recommended practice: 1. Perform one risk assessment per EN ISO 12100; derive both PLr and SIL (the informative correspondence table makes this easy). 2. Write a Safety Requirements Specification (SRS) once — both standards now effectively require it. 3. Choose subsystems whose published data covers both worlds (most safety components are dual-rated). 4. Verify the PFHd budget once; it is the common currency. 5. Claim "PL e, Category 4, SIL CL 3" style dual ratings in datasheets and DoCs — this is exactly how the leading safety sensor suppliers present Type 4 products. 6. Validate per ISO 13849-2 requirements (now embedded in ISO 13849-1:2023 Clause 10) and the validation provisions of IEC 62061; keep one technical file for both.

7. What this means for safety light curtains (ESPE)

Electro-sensitive protective equipment (light curtains, light grids, area scanners) is designed to EN/IEC 61496 (Part 1 general, Part 2 AOPD, Part 3 AOPDDR) and rated for functional safety as follows:

Two practical takeaways for buyers: 1. "Type 4" is the top ESPE class — it corresponds to the highest PL/SIL ratings a machine can claim, suitable for hazards with serious injury potential (PL e / SIL 3). 2. Type examination matters. Because EN/IEC 61496 is not a harmonized standard under the EU Machinery Directive/Regulation, there is no automatic presumption of conformity — independent type examination by a recognized body (e.g., TÜV, DEKRA, SGS) is the established market practice. A DADISICK Type 4 safety sensor carries type-examination and dual PL e / SIL 3 claims so integrators can rely on the numbers without re-deriving them.

8. Version and harmonization status — keep this table current

Regulatory timeline to watch (EU): - Until 19 January 2027: Machinery Directive 2006/42/EC applies; Declaration of Conformity may reference both Directive and Regulation if compliant. - From 20 January 2027: Machinery Regulation (EU) 2023/1230 applies exclusively (no transition period). Harmonized standards for the Regulation are expected to carry over with minor adjustments — apply EN ISO 13849-1:2023 and EN IEC 62061:2021 now to be future-proof. - The Regulation adds: software/cyber-security requirements for safety functions, stricter conformity assessment for higher-risk machinery, new economic-operator duties (importers/distributors), and digital technical documentation.

9. References and sources

• ISO 13849-1:2023, Safety of machinery — Safety-related parts of control systems — Part 1: General principles for design (ISO; 4th edition, 2023).
• ISO 13849-2:2012, … Part 2: Validation (ISO).
• IEC 62061:2021 + AMD1:2024 + AMD2:2026, Safety of machinery — Functional safety of safety-related control systems (IEC; 2nd edition, 2021).
• IEC 61508 (all parts), Functional safety of electrical/electronic/programmable electronic safety-related systems (IEC).
• EN ISO 12100:2010, Safety of machinery — General principles for design — Risk assessment and risk reduction.
• EN/IEC 61496 series (Parts 1, 2, 3), Safety of machinery — Electro-sensitive protective equipment (IEC 61496-1:2020, 4th ed.).
• Regulation (EU) 2023/1230 on machinery, OJ L 165, 29 June 2023 (EUR-Lex) — applicable 20 January 2027.
• European Commission, Machinery sector page and harmonized standards database (single-market-economy.ec.europa.eu).
• ISO Online Browsing Platform (iso.org/obp) — edition/status verification.
• Pilz, EN/IEC 61496 and IEC 62061 technical reference pages (pilz.com) — PFHd/SIL tables and harmonization status.
• DGUV Test, EU Machinery Regulation conformity-assessment guidance (dguv.de).

Document control: verify standard editions and OJEU citation status at least annually or before publishing updates. Last verified: 2026-08.