Where the numbers come from.

How it is calculated

Everything is linear and can be redone by hand. A month is 52 ÷ 12 = 4.33 weeks. Euros are shown rounded to the nearest ten so they don’t look more precise than they are.

1. Bookings per month = bookings per week × 4.33
2. Missed calls per week = what the business reports; if unknown, bookings per week × 25%
3. Calls answered per month = missed calls per week × 4.33
4. Bookings recovered per month = missed calls per week × 50% that wanted to book × 20% that never call back × 4.33
5. Revenue from calls = bookings recovered per month × average revenue per booking
6. No-shows per month = last month’s figure reported by the business (never more than the month’s bookings); if unknown, bookings per month × industry average
7. No-shows prevented = no-shows per month × 30%
8. Revenue from no-shows = no-shows prevented × average revenue per booking
9. Hours freed up = bookings per month × 3 minutes ÷ 60
10. Value of time = hours freed up × €13 per hour
11. Total per month = revenue from calls + revenue from no-shows + value of time; per year, × 12

The assumptions

Each one can be changed from the calculator (“Adjust the assumptions”). The values are cautious on purpose: better to undershoot than to oversell.

Values by industry

Bookings and average revenue are just a starting point so the calculator shows something before the business enters its own figures. The no-show average only applies when the business doesn’t know its own.

The sources

We dropped the viral figures with no study behind them (such as “85% never call back” or “$126,000 lost a year”). Where no reliable data exists, we say so and start from the lowest value.

1. TheFork · no-shows in Spanish restaurants (2025)

   Average no-show rate of 3.3% on its platform (3.5% in Barcelona), where 6 in 10 restaurants already reconfirm automatically. 55% of no-shows say they simply forgot. Since it tends to be higher without reconfirmation, the average we use is 5%.

   View source
2. 411 Locals · calls to small businesses (2024)

   Only 37.8% of calls to 85 small businesses across 58 industries were answered by a person. Small US sample: that is why, when a business doesn’t know its missed calls, we estimate just one per four bookings handled, far below that figure.

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3. CallRail · what callers do when nobody answers

   Survey of 1,000 consumers: 21% call a competitor straight away and only 42% leave a voicemail. We only count as lost the callers who have already rung someone else: hence the assumption that 20% of would-be bookers never call back.

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4. Boksmati et al. · SMS reminders and attendance (meta-analysis, 2016)

   28 studies, 13 of them randomised trials: attendance odds ratio of 1.62 with a reminder. On a 10–20% no-show rate that is 30–45% fewer no-shows: we take the low end.

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5. Cochrane · mobile reminders for healthcare appointments

   Systematic review: attendance risk ratio of 1.10 with text reminders versus none. A modest but consistent effect.

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6. Missed medical appointments in Spain

   Regional studies put missed appointments at 8–13% (9.7% in the Valencian Community over 7 million appointments; 8–12% according to Internal Medicine). The average we use is 10%.

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7. Published ranges for salons and beauty centres

   Industry compilations put hair salons and barbershops at 5–12% no-shows and spas and beauty centres at 10–20%. These come from software vendors: the average we use is 8%, at the low end.

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8. Spanish minimum wage 2026 · Royal Decree 126/2026

   €1,221 gross per month in 14 payments (€17,094/year). With 31% employer contributions and about 1,780 working hours a year, the hourly cost is around €12.6. Hospitality agreements sit slightly above: we use €13.

   View source
9. Our own assumption

   We found no reliable study behind it: it is a cautious estimate so you have a starting point. Replace it with your own figure.

Sources checked on 13 October 2026.