How to use the calculator
Every box starts with an example figure so you can see how it works. Replace each one with your own; the result updates as you type.
- Calls a week. Count every incoming call in a normal week from your phone's call log, answered or not.
- Which calls go unanswered. Choose "Calls I miss" and enter missed calls as a share of all calls, or choose "Calls when we're closed" if you mostly want to know what evenings and weekends cost you.
- New customers or bookings. Of those unanswered calls, the share that would have become paid work. Numbers you don't recognise are a fair guide.
- Average value. What a typical new booking or job is worth to you. Pick £, $ or € for the display; amounts aren't converted.
- Missed callers who don't call back. The share who never ring again, so the work is likely lost rather than delayed.
How the numbers are worked out
The sum is short, and the result panel shows it with your figures filled in:
Calls a week × share unanswered × share that are new customers or bookings × share who don't call back = lost bookings a week. Lost bookings × average value = lost revenue a week.
The month is the week × 4.33 (52 weeks ÷ 12 months) and the year is the week × 52. With the example figures, 40 calls × 25% missed is 10 unanswered calls; half are new customers, so 5; half of those don't call back, so 2.5 lost bookings a week, and at £150 each that's £375 a week. Those example figures are made up to show the sum, not typical of any trade.
What the result leaves out
Treat the result as a rough guide to compare with the cost of answering more calls, not as a forecast. It can be too low or too high:
- Some customers come back for more work or recommend you, so a lost first job can cost more than its own value.
- Urgent or out-of-hours work is often worth more than an average job.
- A caller who does ring back may already have booked someone else, so "called back" isn't always "won".
- Not every new enquiry turns into a job even when you answer, so lower the new-customers share if you only win some of them.
For more on the sum and how to get your own figures, read what a missed call costs a small business. To compare answering options, see how call answering services are priced in the UK.
Questions
How do I find out how many calls I miss?
Open your phone's call log, or your phone provider's online account, and count a normal week: all calls in, and the ones nobody answered. If you have more than one line, add them together. A week or two of real numbers beats any guess.
Why doesn't the calculator use an industry figure for callbacks?
Published figures for how many callers ring back come from different industries, countries and surveys, often run by companies selling call answering. They rarely match a local business, so the calculator asks for your own figure instead. The numbers filled in when the page opens are examples, not averages.
How do I estimate how many missed callers don't call back?
Take the missed calls from numbers you don't recognise and check how many of those numbers rang again within a day or two. The share that never rang again is your figure. It won't be exact, but it's your own.
What counts as a new customer or booking?
A call that would have turned into paid work if someone had answered: a new enquiry, a quote request that usually leads to a job, or a booking. Leave out existing customers chasing a job, suppliers and sales calls. If not every new caller would book, lower the figure to the share you'd usually win.
Does the calculator save or send what I type?
No. The sums run in your browser and the figures you enter aren't sent or stored. We only count that the calculator was used, not what was entered.
Why is the monthly figure not four times the weekly one?
A year has 52 weeks, so an average month is 52 ÷ 12, about 4.33 weeks. The monthly figure is the weekly figure × 4.33 and the yearly figure is the weekly figure × 52.
Checked 27 Oct 2026. No outside statistics are used: every figure comes from you. General information, not financial advice.