Short answer: use this formula:
Monthly lost revenue = missed calls per month x % that were new prospects x % you would have booked x average first-job value
Add lifetime value for repeat customers and the real figure is higher. Plug your numbers into the free missed call revenue calculator to get a monthly and yearly figure in seconds.
Why missed calls are so expensive
A caller with an urgent need (a leaking pipe, a toothache, a viewing request) rarely leaves a voicemail. They call the next business on the list. Unlike a lost website visitor, they were ready to buy. And because missed calls do not show up in your sales reports, the loss is invisible until you measure it.
Step 1: Find your real missed-call numbers
- Export 30 days of call logs from your phone system, VoIP provider or mobile carrier.
- Count calls that were not answered, went to voicemail or were abandoned on hold.
- Note when they happened: after hours, lunch, during jobs, Mondays. The pattern tells you which fix you need.
- Check how many of those numbers ever called back or booked. Usually few.
Step 2: A worked example
| Input | Example value |
|---|---|
| Missed calls per month | 120 |
| Share that were new prospects (not spam or existing customers) | 40% = 48 calls |
| Share you would normally book when answered | 50% = 24 jobs |
| Average first-job value | USD 250 |
| Lost revenue per month | USD 6,000 |
| Per year | USD 72,000 |
These are illustrative numbers for a home-services business. Use your own; even if you halve every assumption, the result usually dwarfs the cost of fixing it.
Step 3: Choose the fix that matches your pattern
| Fix | Best when | Limits |
|---|---|---|
| Conditional call forwarding to a colleague | Small overflow during the day | Someone still has to be free |
| Missed-call text back | Callers who will continue by text | Some callers just call a competitor |
| Human answering service | Complex or sensitive calls | Per-minute cost, often message-taking only |
| AI receptionist | After hours, overflow, high volume, booking needed | Needs a handoff rule for emergencies |
| Hire a receptionist | Steady daytime volume and in-person front desk | Salary, cover for breaks and holidays |
For a cost comparison of these options, read AI vs human answering services and AI receptionist cost.
Quick wins you can do today
- Record a voicemail that promises a callback time and offers a text option.
- Turn on missed-call text back with a booking link.
- Put "Book online" next to every phone number on your website.
- Call back every missed number within 15 minutes, starting today.
Frequently asked questions
What percentage of callers leave a voicemail?
It varies by industry and caller, but in most small businesses only a minority do. Check your own logs: compare missed calls with voicemails received.
Should I include spam calls?
No. That is why the formula multiplies by the share that were real prospects. If you cannot tell, sample 20 missed numbers and look them up.
What is the fastest fix?
Missed-call text back takes minutes to switch on. An AI receptionist takes a day or two to set up properly and answers the call itself, which converts better than a text.
Does this apply to B2B companies?
Yes, often more so: the value of one lost enquiry is higher, even if call volume is lower.
Answer every call
Work out your number with the calculator, then let ZetDesk AI Receptionist answer, book and summarise every call 24/7. See industry setups for HVAC and plumbing, dental practices and law firms.
