Rule-of-thumb estimate — Accounting glossary

A rule-of-thumb estimate uses a simple practical guideline to produce an approximate answer. It can help when time, detailed information or analytical resources are limited, but its assumptions and range of usefulness should be explicit. Check the guideline against relevant evidence and update it when conditions change; a quick rule is not inherently a statistically fitted regression or a reliable substitute for detailed analysis.

Worked example

For an initial draft budget, a manager estimates next month’s delivery cost as $5 per expected order: 800 orders give $4,000. Before approval, the team checks actual invoices and whether delivery distances, order size and fuel charges make that rule appropriate.

Common mistake

Treating a convenient rule as a validated forecast regardless of changing conditions, or confusing it with an estimated regression model.

Where it appears in your exams

Qualification	Exam	Relationship	Period
ACCA	PM	Supporting	September 2026–June 2027