Work Instructions vs SOPs: How to Write Ones Operators Actually Use

Work instructions vs SOPs: an SOP sets out a process and who owns it; a work instruction shows one task step by step. How to write and control both.

Verika Editorial·7 October 2026·7 min read

Short answer: An SOP (standard operating procedure) sets out a whole process, who owns each part and what records it produces. A work instruction shows one operator how to do one task at one station, step by step. ISO 9001:2015 doesn't dictate either format, but clause 7.5.3 requires controlled documents that are available where and when needed.

Most plants have plenty of documents. The problem is that operators don't use them. The SOP is twelve pages written for an auditor, the work instruction at the machine is three revisions old, and the real method lives in the head of the operator on days. This post sets out the difference between the two documents, how to structure each, and how to keep the right version at the point of use.

What is the difference between a work instruction and an SOP?

An SOP answers "what is our process and who does what?" A work instruction answers "how exactly do I do this task here?" They sit at different levels and are written for different readers.

	SOP	Work instruction
Covers	A process across people, shifts or departments	One task at one station or machine
Reader	Supervisors, engineers, quality, auditors, new leads	The operator doing the task
Answers	What, who, when, which records	How, with which settings and tools
Typical content	Purpose, scope, responsibilities, process steps, records, references	Numbered steps, photos, settings, tolerances, checks, safety warnings
Length	A few pages	One page or one screen per task
Example	"Changeover procedure for packing lines"	"Change format parts on Line 3 filler, 250 ml to 500 ml"
Changes when	The process or responsibilities change	The machine, tooling, part or setting changes

A simple test: if the document would be the same on every line in the plant, it's probably an SOP. If it only makes sense standing at one machine, it's a work instruction.

Many plants also use forms and records below work instructions, such as checksheets and logs. The SOP says which records are needed; the work instruction says when the operator fills them in.

What does ISO 9001 say about SOPs and work instructions?

ISO 9001:2015 doesn't use the terms "SOP" or "work instruction" as requirements. It uses "documented information", and leaves the format to you.

The parts of clause 7.5 that matter here:

Maintained vs retained. Documents you keep current (procedures, instructions) are "maintained" documented information. Evidence of what happened (records, checksheets, training records) is "retained" documented information.
7.5.2, creating and updating. When you create or update documented information, ensure appropriate identification and description (such as a title, date, author or reference number), format and media, and review and approval for suitability and adequacy.
7.5.3.1, control. Documented information must be controlled to ensure it is "available and suitable for use where and when it is needed" and "adequately protected (e.g. from loss of confidentiality, improper use, or loss of integrity)."
7.5.3.2, control activities. As applicable: distribution, access, retrieval and use; storage and preservation, including legibility; control of changes (e.g. version control); and retention and disposition.

"Where and when it is needed" is the line that matters for operators. A perfect work instruction locked in the quality office fails that test.

A note on editions: this summary is of ISO 9001:2015, taken from published clause summaries rather than the standard itself. LRQA reported that a revised edition, ISO 9001:2026, was scheduled for publication on 16 September 2026, with a transition period expected to run to around September 2029. We have not checked whether clause 7.5 changed. Ask your certification body which edition you're being audited against.

How should you structure an SOP?

Keep the SOP at process level and push detail down into work instructions. A workable structure:

Title, reference number, revision and date.
Purpose. One or two sentences.
Scope. Which lines, products, sites or shifts it covers, and what it doesn't.
Responsibilities. Roles, not names: "shift lead", "quality technician".
Process steps. Numbered, at the level of "who does what next". Link to the work instruction for each task.
Records. What gets recorded, where, and how long it's kept.
References. Related SOPs, work instructions, regulations or customer requirements.
Owner and approval. Who owns it, who approved it, when it's next reviewed.

If a step in your SOP has settings, torque values or photos, it belongs in a work instruction.

How do you write a work instruction operators will actually use?

Write it at the machine, with an operator, in the words the operator uses. Then test it on someone who hasn't done the task before.

One task per instruction. "Change the reel on Wrapper 2", not "Wrapper 2 operation".
Start with what you need. Tools, parts, PPE and any preconditions ("machine locked out per the energy control procedure").
One action per step, starting with a verb. "Loosen the two clamp levers." Not "The clamp levers should be loosened and the guide moved."
Show it. A photo or simple drawing for any step where a new operator could pick the wrong part, direction or setting. Mark the photo with arrows or numbers that match the step.
Give the numbers. Settings, torques, temperatures and tolerances, with units, at the step where they're used.
Put warnings before the step, not after. A caution that appears after the hazardous step is read too late.
Build in the check. End with how the operator knows it's right: first-off inspection, gauge check, sign-off.
Name the record. If the task needs a record, say which form and where it goes.
Test it cold. Give it to an operator from another shift. Watch, don't help. Every place they hesitate is a step to fix.

Example: weak vs usable step

Weak: "Set up the guide rails correctly for the product."

Usable:

Loosen the two black handwheels on the infeed guide rail (photo 3).

Slide the rail until the pointer reads 82 on the scale.

Tighten both handwheels. Push the rail by hand; it must not move.

The second version answers the question an operator would otherwise have to ask someone.

Where safety is regulated, follow the rule

Some tasks have legally required procedures. In the US, OSHA's lockout/tagout standard requires documented energy control procedures for machine servicing and maintenance, with specific content. Your work instruction for clearing a jam or changing tooling should refer to, and match, that procedure. See what OSHA 1910.147 requires for the details.

How do you control versions without slowing everything down?

Keep one master copy, number every revision, approve before release, and remove the old version from the point of use the same day.

Revision on every page. "WI-PK-014 Rev C, 12 March". Operators should be able to see it's current.
One master. A controlled folder or document system. Printed copies are marked as controlled and counted, or marked "uncontrolled when printed" and not used at the machine.
Approval matches risk. A wording fix might need the area owner only. A changed setting or safety step needs quality or engineering too.
Change record. Each revision says what changed and why, in one line.
Retire the old. When Rev D goes up, Rev C comes down, physically and on screen. This is the step most often missed.
Review triggers. Review after a defect, a near miss, a machine or tooling change, or when operators keep asking the same question about a step.

How do you keep instructions at the point of use?

Put each work instruction where the task happens, in a form the operator can read without stopping the job. On paper, that's a holder at the machine with only current versions in it. On screen, that's a terminal or tablet at the station, opening on the right instruction for that machine.

The test is simple. Stand at the machine and ask an operator to find the instruction for a task they rarely do. If it takes longer than a minute, they'll ask a colleague or rely on memory, and your controlled document isn't being used.

Verika can help with the "find it" part. Once your SOPs and work instructions are uploaded or synced from Google Drive or SharePoint, an operator can ask "what's the guide rail setting for 500 ml on Line 3?" by voice and Verika answers from WI-PK-014, naming the document. If no document covers it, Verika says so instead of guessing and logs the question for an engineer to answer. It doesn't replace your document control; it answers from what you've approved. See our manufacturing page for more.

Sources

Auditor Training Online, "Explaining ISO 9001 Clause 7.5.3 Control of Documented Information" (quotes clause 7.5.3.1 and 7.5.3.2 of ISO 9001:2015). https://blog.auditortrainingonline.com/blog/explaining-iso-9001-clause-7.5.3-control-of-documented-information
Open Exam Prep, "Clause 7.5 — Documented information" (ISO 9001:2015 clause 7.5.2, maintained vs retained documented information). https://open-exam-prep.com/study-guides/cqi-irca-qms-lead-auditor/clauses-6-7/clause-7-documented-info
LRQA, "ISO 9001 publication date confirmed" (ISO 9001:2026 scheduled publication and expected transition). https://www.lrqa.com/en-gb/latest-news/iso-9001-publication-date-confirmed/
OSHA, 29 CFR 1910.147, The control of hazardous energy (lockout/tagout), paragraph (c)(4). https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.147

Frequently asked questions

›What is the difference between an SOP and a work instruction?

An SOP describes a process: what happens, in what order, who is responsible and what records are kept. A work instruction tells one person how to do one task at one workstation, step by step, usually with photos and settings.

›Does ISO 9001 require SOPs or work instructions?

ISO 9001:2015 does not prescribe a set of SOPs or work instructions. It requires the documented information your quality management system needs, and clause 7.5.3 requires that information to be controlled so it is available and suitable for use where and when it is needed.

›How long should a work instruction be?

As short as the task allows. One page or one screen per task, with one action per step, is a practical target for most machine and assembly tasks.

›Where should work instructions be kept?

At the point of use: at the machine, bench or line, on paper or a screen, in the current approved version only. Copies in a desk drawer go out of date.