FMEA worksheet

How it works

A failure mode and effects analysis lists how a design or a process could fail, what that would do, why it would happen, how the cause is prevented and how the failure would be found, then ranks the risks so the team acts on the worst first. This worksheet keeps the whole analysis as rows, ranks them by risk number or by your own action rules, and follows each action to closure.

1. Choose design or process. A design FMEA looks at an item and its functions: the failure is the item not doing its function, and the controls are design rules, reviews, simulation and test. A process FMEA looks at a step: the failure is the step not delivering its requirement, and the controls are error-proofing, set-up, monitoring and inspection. The column names change with your choice; the maths does not.
2. Rate severity, occurrence and detection. Severity (S) is how bad the effect is, from 1 (none) to 10 (harm without warning). Occurrence (O) is how likely the cause is, given the prevention control, from 1 (cannot happen) to 10 (expected). Detection (D) is how likely the controls are to find the cause or the failure before it reaches the next stage, from 1 (certain) to 10 (no chance). The one-line guides under the sheet describe each band in plain words; use your company's own scales where you have them.
3. Rank with the risk number. The classical ranking multiplies the three ratings. The result runs from 1 to 1,000. The tool bands it with two thresholds you can change (200 and 100 by default, which are editorial). Two rows with the same number can be very different risks, for example 9 x 2 x 5 against 3 x 6 x 5, so look at severity first.RPN = S x O x D; High if RPN is at or above the high threshold, Medium if at or above the medium threshold, else Low
4. Rank with severity-first action rules. Instead of multiplying, a rule set reads the three ratings in turn. Each rule says: if S is at least a value, and O is at least a value, and D is at least a value, the row is High (or Medium). A row takes the highest band among the rules that apply, and is Low when none does. The Hub default rule set puts severity first, so a severity of 9 or 10 is never Low. You can edit, add and remove rules. The AIAG and VDA FMEA handbook (first edition, 2019) defines its own action priority table; that table is not reproduced here. If your customer requires it, enter its rules as your own rows.priority = highest band among the rules where S >= minimum S and O >= minimum O and D >= minimum D
5. Criticality. Severity times occurrence ignores detection and shows how bad and how likely a failure is before any inspection. It is shown for every row, and the matrix counts the rows in severity and occurrence bands. This is the idea behind the criticality ranking of FMECA in IEC 60812.criticality = S x O
6. Follow the actions. Each action has an owner, a due date and a status. An action is overdue when its due date is before today and it is not done or marked not needed. When an action is done, the member enters the revised ratings, and the tool compares the risk number and the priority before and after.overdue days = today − due date; reduction = RPN before − RPN after

Sources

The methods and default figures rest on these public sources. The wording here is our own; read the source for its full text.

• AIAG & VDA FMEA Handbook, first edition, Automotive Industry Action Group (AIAG) and Verband der Automobilindustrie (VDA), June 2019. The seven-step method and the action priority approach; cited by name only, and its tables are not reproduced.
• IEC 60812:2018, Failure modes and effects analysis (FMEA and FMECA) (opens in a new tab), International Electrotechnical Commission, third edition, 10 August 2018. The generic method, criticality ranking and the alternative ways of calculating a risk number; cited by name only.
• Failure Mode and Effects Analysis (FMEA) (opens in a new tab), ASQ (American Society for Quality), undated page, checked October 2026. A public overview: failures ranked by the seriousness of the effect, how often they happen and how easily they are detected.