What is a standard operating procedure (SOP), and how is it different from a work instruction?
What an SOP is, how it differs from a process, a policy and a work instruction, what official guidance says it should contain, and why many go unfollowed.
A standard operating procedure (SOP) is a written document that says who does what, in what order and under which conditions, so that a routine activity gives the same result every time. A work instruction is more detailed: it explains how to carry out one task, step by step, at the place where the work happens. A process is broader than both. It describes what happens from start to finish, and why.
In practice, people confuse these terms. One company calls a two-page document a procedure, and another gives the same name to a 40-page manual. This guide explains the terms, what official guidance actually says about them, and what a procedure needs to contain for people to follow it.
SOP, process, policy and work instruction side by side
The table goes from the widest term to the most precise, with an IT support team as the example:
| What it says | In IT support | Who reads it | |
|---|---|---|---|
| Policy | the rules and commitments | the response times promised to users | management, auditors |
| Process | what happens from start to finish, and why | incident management, from report to closure | managers, auditors |
| Procedure (SOP) | who does what, in what order, under which conditions | handling a critical incident: who is told, who decides, when to escalate | the teams doing the work |
| Work instruction | how to carry out one task, step by step | restarting the email service | the person doing the task |
Three more words often appear next to these. In the European rules for manufacturing medicines, a protocol gives instructions for carrying out and recording one specific operation. For the UK Health and Safety Executive (HSE), a checklist can be a short form of procedure. A record does not say what to do at all: it proves that the work was done. An incident ticket with its history is one example.
What official guidance says an SOP is
Public bodies define the term in similar ways. The US Environmental Protection Agency (EPA) defines an SOP as a set of written instructions that document a routine or repetitive activity, technical or administrative. Its guidance on preparing SOPs dates from 2007, and the EPA still publishes it in its list of quality guidance documents.
In medicine manufacturing, chapter 4 of the EU good manufacturing practice guidelines has been in force since 2011. It treats "procedure" and "SOP" as two names for the same thing: directions for carrying out certain operations. It also asks for an imperative, mandatory style. The guidance of the World Health Organization (2014 edition) adds two points: an SOP is an authorised written procedure, and it can cover an operation that is not tied to any one product, such as cleaning a piece of equipment.
The HSE gives the plainest definition: procedures are agreed safe ways of doing things. A written procedure is usually a list of steps plus the information needed to do the task safely. It can also take the form of a checklist, a diagram or a flowchart.
Is the document pyramid a standard?
Many web pages show a pyramid with four levels, from policy down to work instruction, as if it came from a standard. ISO's quality guidance did describe a hierarchy once, but none of the current sources we read defines one.
- ISO 10013, the ISO guidance on documenting quality management systems, has not prescribed a hierarchy since its 2021 edition, because electronic documents can be organised in many ways.
- The EPA lists instructions and protocols as other possible names for an SOP.
- The EU manufacturing guidelines name work instructions next to procedures, without defining them.
So the terms are yours to choose. Decide what your organisation calls a procedure, what it calls a work instruction, and who approves each. Write this down once, in a short document. After that, the debate about words stops, and everyone knows which document to look for.
How much detail an SOP needs
The right level of detail depends on the task and on the person, not on the name of the document. In a 2007 guide that it still publishes, the HSE uses four criteria: how serious an error would be, how complex the task is, how often it is done, and how experienced the person doing it is. A task that is critical, complex, rare or given to a beginner needs detailed steps. A simple, frequent task that is not critical, done by an experienced person, needs only a job aid, such as a checklist, a diagram or a flowchart.
The HSE draws one rule from this: the more rarely a procedure is used, the more detailed it must be. So check your rare procedures first: disaster recovery, the year-end close, the emergency stop of a machine. These are the ones that lack detail on the day someone needs them.
What an SOP contains
Public guides each use their own outline, and they overlap a great deal. We combined four of them: the EPA guidance, two HSE guides and the guidance of INRS, the French institute for occupational safety. Together, they list these parts:
- purpose and scope: what the document is for and when it applies;
- starting conditions: what must be true before you begin;
- roles: who carries out the task, who is authorised, who approves;
- tools, equipment and personal protective equipment;
- the steps, with one action per step;
- risks and precautions, at the step where they arise;
- related documents;
- the version, the date and the person who approved the document.
Two practices stand out. The people who do the work help write the procedure: the EPA and the HSE both ask for it, and INRS asks for an analysis of how the work is really done, through observation and interviews with operators. The EPA also recommends that someone other than the author tests the procedure before it is finalised.
Our guide on how to write SOPs that teams actually use covers the writing method in detail, and our SOP template gives you the structure.
Why SOPs are not followed
The HSE lists some of the most common reasons why a written procedure is not followed:
- it is wrong or out of date;
- it is hard to use;
- it is not available where the work is done;
- there is an easier way to do the job;
- people do not understand the risks;
- colleagues put pressure on them;
- they feel pressure from managers to get the job done.
The HSE also warns against two mistakes: assuming that everyone follows the procedure, and relying on the procedure as the only safeguard. It advises against banning the personal notes that operators keep, as long as they are safe, and suggests using them to find what the official procedure is missing.
What our customers do
Official guidance says what to write, and it asks for regular review. The EPA gives a review every one to two years as an example. The EU and WHO manufacturing rules ask for regular review but set no interval, and INRS ties updates to changes at the workstation. The EPA asks each organisation to name who keeps its procedures current, and the HSE asks for a way to train staff when a procedure changes. None of the texts we read says what happens to a procedure when its author leaves, or how to make sure training and daily work use the same version.
Three customers show what the answers look like in practice. At the Département de l'Orne, a French local authority, 25 IT professionals maintain the procedures that 1,800 staff depend on. Every procedure has an expiry date, and an annual review starts automatically. Nothing stays active without being checked.
At SPIE ICS, every procedure has an owner, who is notified when the review is due. Technicians flag a wrong step directly in the procedure, and the owner decides on the change. At Fnac Darty, trainers and customer advisors work from the same current procedures: more than 2,000 of them, in one place. So the version used in training is the version used on the job.
This is what we build with Elium: procedures that each have an owner, a review date and access rights, on one platform that your AI agents read too. Our guide on what a knowledge base is explains how to build one.
Common questions
A standard operating procedure: a written document that says who does what, in what order and under which conditions for a routine activity. The US Environmental Protection Agency defines it as a set of written instructions that document a routine or repetitive activity, technical or administrative.
An SOP covers an activity: the roles, the order of the steps and the conditions. A work instruction covers one task inside that activity, step by step, for the person doing it. One SOP often points to several work instructions. No standard sets these definitions, so agree on them once inside your organisation.
No. A policy states rules and commitments, such as the response times promised to users. An SOP says how to carry out an activity within those rules. The EU manufacturing guidelines list policies and procedures as separate kinds of document.
Purpose and scope, starting conditions, roles, equipment, the steps with one action each, the risks at the step where they arise, related documents, and the version, date and approver. This list combines the guidance of the EPA, the HSE and INRS.
No official text sets a general interval. The EPA gives one to two years as an example, and asks for an update whenever the way of working changes. INRS asks for an update when the workstation or production changes. An expiry date on every procedure makes the review visible.
A process describes a series of operations organised to reach a result: what happens from start to finish. A procedure sets the rules for carrying out one part of that process: who acts, in what order, under which conditions.
Where to start
Of the procedures you rarely use, pick the most critical. Look for its owner and the date it was last checked. If you find neither, start with that one. To see how Elium keeps both on every procedure, book a demo.
Sources
- US Environmental Protection Agency, Guidance for Preparing Standard Operating Procedures, EPA QA/G-6, 2007, and Quality program directives.
- European Commission, EudraLex volume 4, chapter 4: Documentation, in force since 30 June 2011.
- World Health Organization, Good manufacturing practices for pharmaceutical products: main principles, TRS 986, annex 2, 2014.
- ISO/TC 176, Release of ISO 10013:2021, Quality management systems: Guidance for documented information, 2021.
- Health and Safety Executive, Human factors: Procedures, Revitalising procedures (2007) and Core topic 4: Reliability and usability of procedures.
- INRS, Constituer les fiches de poste "machines", ED 126 (in French), third edition, May 2026.