Free toolAI voice agent ROI calculator for missed calls.
Estimate the revenue your unanswered calls put at risk each month. Then check the formula, the assumptions and the sources behind the number.
CalculatorEnter your numbers.
How the calculator works
The calculator multiplies four numbers you already know: calls per day, the share you miss, the share of callers who would have bought, and what a new customer is worth. It assumes a 30-day month.
Missed calls per month = calls per day × 30 × missed rate Revenue at risk / month = missed calls × buy rate × customer value Revenue at risk / year = revenue at risk per month × 12
What the default numbers show
The defaults describe a business that takes 60 calls a day, misses 30% of them and turns a quarter of callers into $400 customers: 1,800 calls and 540 missed calls a month, 135 lost customers, and $54,000 of revenue at risk a month, or $648,000 a year. For a step-by-step walk-through and how the result moves as the miss rate changes, read what missed calls really cost.
What to enter in each field
Enter numbers from your own call log and CRM wherever you have them. The defaults are a starting point, not a benchmark, and each slider has a fixed range.
| Input | Default | What to enter |
|---|---|---|
| Calls per day | 605–400 | Inbound calls only, averaged across every day of the month. Above 400 a day, run each line or location separately. |
| Calls you miss | 30%5–70% | Count a call as missed when no person picked up, including calls that went to voicemail. Enter the rate for calls from potential customers only. |
| Value of a new customer | $400$50–$5,000 | Enter profit rather than revenue for a cautious result. For repeat customers, enter what one is worth over a typical year. |
| Callers who'd buy | 25%5–60% | Use the booking or close rate your team gets on answered calls today. Using the same rate keeps the estimate from assuming the agent sells better than your team. |
No call log? A 2016 study by 411 Locals found that 62% of calls to 85 small businesses were not answered by a person, counting voicemail. It is old and small, so treat it as a ceiling rather than a default.
Assumptions built into the calculator
The result is revenue at risk, not revenue a voice agent is guaranteed to recover, because the calculator makes five simplifying assumptions:
- Every month has 30 days and the same daily call volume.
- Every missed call is a new prospect. Nobody calls back and no voicemail is returned.
- Missed callers would have bought at the same rate as the callers you answer.
- Each new customer is worth one fixed value, with no seasonality.
- Nothing is subtracted for the cost of building and running a voice agent. The next section does.
From revenue at risk to payback
Payback is the one-time cost divided by the net revenue the agent wins back each month, after its running cost.
Payback (months) = one-time cost ÷ (revenue recovered per month − running cost per month)
Say the agent wins back 25% of the default $54,000, or $13,500 a month. Answering the 540 calls you used to miss, at 3 minutes each and Retell's highest listed rate of $0.31 per minute as a cautious ceiling, costs about $500 a month. Our $5,000 Discovery Sprint is credited to the build, so the one-time cost is the build price: payback is about 1.9 months at the low end of our published range ($25,000) and about 9.2 months at the top ($120,000). Your build price is fixed after discovery; see pricing for what each plan includes, and AI voice agent cost for per-minute rates line by line.
Why answering fast matters
Speed changes outcomes before and during the call. A study in Harvard Business Review that audited 2,241 US companies found that firms which tried to contact a web lead within an hour were nearly seven times as likely to qualify it as firms that tried an hour later. On the call itself, people leave gaps of about 200 ms between turns, and that is the pause a caller compares a voice agent against. See how we build them on our AI voice agents page.
Sources
FAQCalculator questions.
How does the calculator estimate lost revenue?
It multiplies calls per day by 30 to get calls per month, applies your missed-call rate, then multiplies the missed calls by the share of callers who would have bought and the value of a new customer. With the defaults that is 540 missed calls and $54,000 of revenue at risk a month.
What missed-call rate should I enter?
Enter the rate from your own call log, counting voicemail as missed. Without a log, start low: the often quoted 62% comes from a 2016 study by 411 Locals of 85 small businesses, and includes calls that went to voicemail. The slider runs from 5% to 70%.
Does the result include the cost of a voice agent?
No. The calculator shows revenue at risk before any costs. To get payback, divide the one-time cost by the revenue the agent wins back each month minus its running cost. In our example, a $25,000 build that recovers $13,500 a month pays back in about 1.9 months, and a $120,000 build in about 9.2 months.
What does an AI voice agent cost to run per minute?
Running costs are usage-based. Retell lists $0.07 to $0.31 per minute depending on the model and voice, and Vapi lists a $0.05 per-minute platform fee with speech, model, voice and phone providers billed on top. A custom build pays the same underlying providers directly.
Should I trust the estimate as a forecast?
No. It is a sizing tool, not a forecast. Some missed callers call back or leave a voicemail, and an agent will not convert every recovered call at your best human close rate. Use it to decide whether the problem is worth a closer look, then test with real call data.
Are my numbers stored or sent anywhere?
No. The calculator runs in your browser and does not save or send your inputs. If you click the button to get a voice agent plan, only the estimated monthly loss is added to the contact form link so you do not have to type it again.
