パーセント計算機

Putting a dollar figure on a meeting

Meetings feel free because no one writes a cheque to attend one — but every minute people sit in a room is paid for in salary. This calculator makes that hidden cost visible. You enter how many people are attending, their average hourly rate, and the planned length, and it shows the cost per minute, the projected total, and — once you press start — a live counter that ticks upward in real time as the meeting runs. Displaying a number that climbs while people talk is a surprisingly effective way to keep a discussion focused.

The arithmetic behind it

The core calculation is deliberately transparent. The tool sums every attendee's hourly rate to get a combined hourly cost, divides by 60 for a per-minute rate, and multiplies by the number of minutes:

• Cost per minute = (sum of hourly rates) ÷ 60
• Planned cost = cost per minute × planned duration
• Live cost = cost per minute × minutes elapsed so far

In quick-setup mode every attendee is assumed to earn the same rate, so the combined hourly cost is simply headcount × rate. If you switch to the Custom Attendees list and give people individual rates, that list takes over and the sum reflects each person's real pay — which is realistic, because a meeting with three engineers and a director costs more than four interns.

A worked example

Five people, an average rate of $60/hour, scheduled for 60 minutes. Combined hourly cost is 5 × 60 = $300. Cost per minute is 300 ÷ 60 = $5.00. The planned cost for the full hour is $5.00 × 60 = $300.00. Press Start Meeting and after the clock reaches 18 minutes the live cost reads $5.00 × 18 = $90.00. If that same meeting runs 12 minutes over, the overrun alone costs another $60 — the kind of figure that justifies ending on time.

The "is this meeting worth it?" check

Enter an estimated dollar value for the meeting's outcome — a decision made, a deal advanced, a problem solved — and the tool divides that value by the cost so far to produce an ROI ratio. A ratio of 2× or more reads as "definitely worth it", at least 1× as "worth it", between 0.5× and 1× as "borderline", and below that as "probably not worth it". The numbers are a rough prompt for judgement, not an accounting standard, but they reframe the question usefully: a one-hour status meeting for eight senior people needs to produce real value to clear its own cost.

Use cases

• Pre-meeting reality check. Type the headcount and length before you send the invite; if the projected cost shocks you, trim the guest list or shorten the slot.
• Live timekeeping. Share your screen with the running counter visible so the group sees the cost accumulate — a gentle, blameless nudge to stay on agenda.
• Recurring-meeting audits. Multiply the per-occurrence cost by how often a standing meeting repeats to expose its true annual price.
• Mixed-seniority meetings. Use custom attendees to model the real cost when executives and junior staff are in the same room.

Tips and common mistakes

• Use fully loaded rates. Salary alone understates cost. A rough rule of thumb is to multiply base hourly pay by about 1.25–1.4 to cover benefits, taxes, and overhead, so the figure reflects what an employee truly costs the business.
• Count preparation and context-switching. The tool measures time in the room, but a meeting also pulls people out of focused work. The displayed number is a floor, not a ceiling.
• Custom attendees override quick setup. Once you add even one custom person, the headcount and average-rate boxes are ignored. Clear the custom list to go back to quick mode.
• The live timer needs the tab open. It runs in your browser; the elapsed clock counts from when you press start and pauses when you press pause.

All calculations happen locally in your browser — nothing about your team, rates, or meetings is uploaded or stored on a server.