Meeting Cost Formula for Mixed Rates, Partial Attendance and Preparation

Use the attendee-level formula

For attendee i, let rᵢ be the hourly cost and mᵢ the meeting minutes. Then:

Attendance cost = Σ(rᵢ × mᵢ ÷ 60).

If everyone stays for the same duration, this equals headcount × average hourly cost × duration in hours. If some people attend briefly and others stay longer, calculate each person or group separately.

Convert minutes to hours before multiplying. Forty-five minutes is 45 ÷ 60 = 0.75 hours, not 0.45 hours. That unit error alone understates the cost by 40% in a 45-minute example.

Worked example: six people with different participation

These are invented loaded hourly costs, not salary benchmarks.

For example, the engineers contribute 3 × $70 × 45 ÷ 60 = $157.50. The director contributes $120 × 20 ÷ 60 = $40. Treating all six people as present for 45 minutes would overstate this meeting's attendance cost.

Total attendee time is 245 minutes, or 4.0833 hours. Dividing $265 by 4.0833 hours gives an attendance-time-weighted average cost of approximately $64.90 per hour. That weighted average can reproduce the total, but the attendee rows are easier to audit.

Add the work outside the meeting

Suppose one analyst spends 20 minutes preparing and one engineer spends 15 minutes documenting actions:

• Preparation: $45 × 20 ÷ 60 = $15.00.
• Follow-up: $70 × 15 ÷ 60 = $17.50.
• Full measured workflow: $265 + $15 + $17.50 = $297.50.

Do not assign these tasks to every attendee unless they actually perform them. If measured transition time matters, add the affected person's time explicitly and identify it as an assumption or observation. There is no universal 1.3 interruption multiplier in this method.

Keep rate loading separate from time loading

An employee's loaded cost may include wages, benefits and employer costs. An assumed 30% cost load would turn a $50 wage rate into $65; it does not mean the employee spends 30% more time in meetings. The BLS distinguishes compensation components, supporting this separation of cost from time. BLS compensation framework

If you already have a loaded $65 rate, adding the same benefit allowance again double-counts it. Similarly, adding preparation minutes and then applying a “preparation overhead” multiplier counts the same time twice.

Annualize actual occurrences

If the worked $297.50 workflow occurs 46 times, modeled annual cost is $13,685. If it occurs monthly, multiply by the planned twelve occurrences, giving $3,570. Do not multiply a weekly figure by 52 when holidays or cancelled meetings reduce the expected count.

A rate scenario is also not an invoice. A consultant charging $100 per hour for one billable meeting hour does not automatically bill $130 because an internal model has an overhead assumption. Billing must follow the agreed arrangement.

Use a calculator without hiding the detail

The meeting cost calculator is useful for equal-rate or average-rate scenarios. If it cannot represent partial attendance, calculate the groups separately and sum them. Keep the source rows and explicit assumptions so another person can reproduce the result.

For choosing whether to shorten, reduce attendance or replace the meeting, use the meeting-cost decision guide. The formula measures resource use; the purpose and results determine whether that use was worthwhile.