How much is your phone line leaking? Work it out from last month's call log
How to calculate missed call revenue from three numbers
To calculate missed call revenue, you need three numbers from last month: how many real callers you never reached, what share of them would normally have booked, and what a booking is worth to you. Multiply them and you get the most those missed calls could have cost you. Existing clients get their own line, because a regular who gives up on you can take future work with them, not just one job.
Everything here runs on your own call log. Many online missed-call calculators pre-fill trade averages and treat every missed call as a lost new job, which tends to inflate the answer and hides the difference between a stranger and a regular. Your log already knows who called, when, and how the call ended. The worked example further down uses sample numbers, so swap in your own as you go.
A note on currency before you start. The sums work the same way in Australian and US dollars. Australian readers should use job values excluding GST, because GST passes through to the ATO and isn't revenue you keep. US readers should use job values before sales tax. The result is shown in AUD and USD side by side.
What to pull from your phone system, and what each call status means
Export last month's inbound calls from your phone system or job software as a spreadsheet. Pick a normal month. If your work is seasonal, run it again for your busiest month too. For many Australian trades that is summer, roughly December to February, with air-con and storm work. US plumbing and HVAC businesses often peak with winter freezes instead.
Look for a report called call history, call log or call detail, set the date range to last month, and download it as CSV or Excel. If your business runs on mobiles with no shared phone system, it is harder. Each phone's recent calls list shows missed calls, but often only for a limited period, and carrier bills tend to list outgoing calls rather than incoming ones. In that case, note down missed calls from today and run the sums at the end of the month.
You want one row per call with the date and time, the caller's number, and how the call ended. Labels vary between systems, but most logs use something close to these:
| Call status | What it usually means | Count it as unanswered? |
|---|---|---|
| Answered | Someone on your team picked up | No |
| Missed or no answer | It rang out and nobody picked up | Yes |
| Voicemail | The caller reached voicemail, with or without leaving a message | Yes, unless you called back and spoke to them |
| Abandoned | The caller hung up while waiting on hold | Yes |
| Forwarded | The call was sent on to another number or mobile | Only if nobody answered at the other end |
If you use AutoCall, every completed call is already a record of who called, which direction the call went, who handled it, how long it lasted, how long the caller waited and how it ended. You can filter that history by outcome and date range. The analytics also include a volume heatmap of when calls come in, so after-hours and weekend peaks stand out at a glance.
Add up every unanswered call for the month. In the worked example below, that figure is 120.
Clean the count: spam, wrong numbers and repeat dials
The raw unanswered number is always too high. Before you multiply anything, take out the calls that were never going to be work:
- Spam and robocalls, including unknown numbers that rang once at odd hours and anything your carrier flagged.
- Wrong numbers and personal calls.
- Internal and supplier calls: staff, subcontractors, your wholesaler, the bank.
- Repeat dials. One person who tried four times is one caller, not four. Count unique numbers.
- Callers you reached anyway. If they got through on a later call, or you called back and spoke to them, they weren't lost.
How much of a log is noise? It varies too much for anyone else's figure to stand in for yours. For context only, JustCall's benchmarks post (published 15 September 2026, updated 23 September 2026) cites NextPhone, which "found 45.8% of calls were not leads at all: spam, wrong numbers, and personal calls" across 1,446,980 business calls in 2025. That is NextPhone's claim about its own customers' calls, measured across all calls rather than missed ones. Count your own.
If the same spam number keeps turning up, AutoCall lets you block it, either for a set period or permanently, which keeps next month's log cleaner.
In the example, 120 unanswered calls less 30 noise calls leaves 90. Those 90 calls came from 65 unique numbers, and 15 of those callers were reached later. That leaves 50 real callers nobody spoke to.
Existing clients and new enquiries are worth different amounts
Now split those callers into people who already buy from you and people who don't yet. Match each number against your client list or CRM. A match is an existing client, and no match is a new enquiry. A few will be unclear, such as a client ringing from a work phone, so check any voicemail or notes for those.
With your CRM connected, AutoCall looks up each inbound caller's number as the call arrives, so your team can see an existing client before they answer. For last month's log, a lookup in your spreadsheet does the same job after the fact.
Why split them at all? A new enquiry is worth one possible job, and only if they would have booked. An existing client is worth their next job plus the work they normally give you over the coming year. A regular who can't get through may try someone else and stay there, which is why the formula counts future work for existing clients and not for new enquiries.
For a sense of what existing clients can be worth when you do reach them, a premium vacuum distributor in Western Australia earned $30,000+ over two weeks on a $1,500 monthly AutoCall fee, using AI voice and SMS to call existing clients, which is an outbound reactivation result rather than a missed-call figure.
The formula, worked through with example inputs
Here is the formula in plain words:
Ceiling for the month = new enquiries at risk (new enquiries not reached × new-enquiry booking rate × average first job value) + existing clients' next job (existing clients not reached × existing-client booking rate × next job value)
Upper bound including 12-month work = Ceiling for the month + existing clients not reached × existing-client booking rate × other work they give you in 12 months
Take booking rates from calls you did answer. Of the new enquiries your team spoke to last month, how many booked? Do the same for existing clients. If you don't track this, pick 20 answered calls from each group and count the bookings.
Example inputs (swap in your own):
| Input | Example | Your number |
|---|---|---|
| Unanswered calls last month | 120 | |
| Noise removed (spam, wrong numbers, internal, suppliers) | 30 | |
| Unique callers left after collapsing repeat dials | 65 | |
| Callers reached later | 15 | |
| Real callers never reached | 50 | |
| Of those, existing clients | 20 | |
| Of those, new enquiries | 30 | |
| New-enquiry booking rate | 40% | |
| Average first job value | 450 | |
| Existing-client booking rate | 75% | |
| Existing client's next job value | 300 | |
| Other work an existing client gives you in 12 months | 600 |
Job values are in AUD excluding GST, or in USD before sales tax. These are made-up inputs to show the arithmetic, not benchmarks or AutoCall data.
The sums:
- New enquiries at risk: 30 × 40% = 12 bookings, × 450 = 5,400
- Existing clients' next job: 20 × 75% = 15 bookings, × 300 = 4,500
- Ceiling for the month: 5,400 + 4,500 = 9,900
- Existing clients' other 12-month work: 15 bookings × 600 = 9,000
- Upper bound including 12-month work: 9,900 + 9,000 = 18,900
Example result (same sample inputs, not a currency conversion):
| Line | Australia (AUD, ex GST) | United States (USD, before sales tax) |
|---|---|---|
| New enquiries at risk | A$5,400 | US$5,400 |
| Existing clients' next job | A$4,500 | US$4,500 |
| Ceiling for the month | A$9,900 | US$9,900 |
| Existing clients' other 12-month work | up to A$9,000 | up to US$9,000 |
| Upper bound including 12-month work | A$18,900 | US$18,900 |
Enter your own job values in your own currency. The two columns match only because the example uses the same numbers for both.
Reading the result as a ceiling, not a forecast
In the example, the ceiling for the month, A$9,900 or US$9,900, is the most that month's unreached callers could have been worth. It is not what you lost, and it is not what you would win back. Some of those callers would have booked elsewhere whatever you did, and some will ring again next month. The upper bound including 12-month work, A$18,900 or US$18,900, is the worst case: it assumes every unreached existing client walked away for good, which most won't.
Three habits keep the number honest:
- Run it again with your booking rates halved. If the cautious figure still matters to your business, the leak is real.
- Look at when the unanswered calls happened. If they cluster at lunch, after 5 pm or on Saturdays, you are looking at a staffing and cover question, which is usually fixable.
- Repeat the count next month, the same way. A trend tells you more than a single month.
If the number is worth fixing, the next question is who answers when. Our hybrid phone coverage guide covers that, with your team answering first in business hours.
Questions owners ask about the calculation
Does every missed call count as lost revenue?
No. Spam, wrong numbers, internal calls and repeat dials from the same person aren't lost revenue, and neither is a caller you reached later. Even a real caller only counts at your normal booking rate, which is why the ceiling for the month is a maximum, not a loss figure.
How do I tell existing clients from new enquiries in my call log?
Match each caller's number against your client list or CRM. A match is an existing client, and no match is a new enquiry. Check voicemails or call notes for the few that are unclear, such as a client ringing from a work phone.
Should I include callers who left a voicemail or rang back later?
Include voicemail callers unless your team called them back and spoke to them. Take out anyone who rang back and got through, because they weren't lost. Count each caller once, however many times they tried.
Bring last month's call export to a revenue check
Book a 30-minute revenue check and have last month's call export handy. We'll work through it with you: clean it, split existing clients from new enquiries, and show the revenue at risk using your own booking rate and job value.
Book a 30-minute revenue check, or call AutoCall on 1800 403 307 in Australia or (888) 882-2918 in the US.