The shop is quiet. The phone is quiet. You're between jobs and the calendar has a gap at 2 PM. Nothing's wrong, except that the ring you didn't hear this morning was a $400 spring job, and the caller has already booked the next company on the list.
This pillar gives you a missed call revenue calculator you can use today. Three numbers go in. One monthly number comes out. You can run it on the back of a napkin or in a spreadsheet, and you'll have a defensible figure for what silence costs your shop each month. We'll also walk through where the calculator over- and under-counts, so the number you land on is honest.
The whole thing is one formula:
Monthly missed-call revenue loss = missed calls × close rate × average ticket
That's the missed call revenue calculation, end to end. If you have any two of the three numbers, you can use planning figures for the third. Most owners can get a workable number in five minutes.
If you want a quick reference for the inputs, a simple worksheet to tally your monthly missed calls walks through filling each one in.
This is the count of calls that rang your shop line and weren't answered by a human (or by an AI that captured the lead). The number you want is the missed-call count, not the total-call count.
To find yours: - Phone system log. Most cell carriers, business VoIP providers, and landline carriers show missed calls. If yours doesn't, dial your voicemail box from another line and check the missed-call notification count. - Manual count for one week. Have someone in the shop watch the line for a full business week. Log every call that rang without an answer. Multiply by 4.3 to estimate a month. - Carrier call detail. Your monthly phone bill often shows missed-call counts, especially on business plans.
If you have no data, a planning range contractors often report for a one- to two-truck shop is 15–30 missed calls a month. Use 20 as a planning figure if you have nothing else.
Close rate is the share of answered inbound calls that turn into a booked job. You want your answered-call close rate, not your marketing-lead close rate.
For a deeper look at what close rate to expect on inbound calls, see what close rate should you expect on inbound calls.
Average ticket is the average invoice amount on a booked job — repairs, service calls, and any openers or small installs you do.
For a more thorough walkthrough, see how to calculate your average garage door ticket.
Say your shop: - Misses 18 calls a month (a reasonable number for a busy one- or two-truck shop). - Books about half of the real prospects who reach a human — close rate of 50%. - Has an average ticket of $375.
Monthly missed-call revenue loss: 18 × 0.50 × $375 = $3,375 a month.
That figure is conservative. It assumes a 50% close rate on missed calls if you'd picked up — the same rate as your answered calls. The honest case is that missed calls skew higher intent, so the close rate, if you had answered, would likely be higher. We cover that below.
Across a year, $3,375 a month is $40,500 in lost revenue from missed calls alone. That's a planning figure. Plug in your own numbers and see what yours is.
The same formula with slightly different inputs tells you how sensitive the answer is.
Conservative (low planning numbers): 12 missed calls × 40% close rate × $300 ticket = $1,440 a month.
Middle of the road (typical shop): 20 missed calls × 50% close rate × $375 ticket = $3,750 a month.
Aggressive (busy shop, urgent mix): 30 missed calls × 60% close rate × $450 ticket = $8,100 a month.
Most shops land between the middle and aggressive versions once they actually measure. A few land lower, but they're the exception. The right answer is to use the formula with your own numbers, not to pick from a range.
The three-input formula is honest, but it's a floor, not a ceiling. Three things push the true cost higher.
Missed calls are higher intent than average calls. The caller who hits voicemail is rarely the price shopper collecting three quotes. The price shopper usually gets a live answer on the second or third try. The voicemail caller is often a bottoms-up-funnel caller with a real problem. If your answered-call close rate is 50%, your missed-call close rate, if you'd picked up, would likely run higher — many shops see 60% or better on the after-hours and weekend calls that dominate their missed-call logs.
A booked job is worth more than one ticket. A garage door customer is a relationship, not a transaction. The homeowner with a broken spring today needs an opener replacement in three years and a new door in eight. The lifetime value of a garage door customer walks through the math. If your average customer's lifetime value is $1,000–$1,500, the cost of a missed call is closer to that number than to the first-ticket figure.
Some callers never appear in your log. A homeowner who hangs up after one or two rings, before the system registers a miss, doesn't show up in your missed-call log. They just dialed the next company. We cover the size of this leak in the calls you don't know you missed — it's the silent majority of the missed-call problem.
Honesty goes both ways. The three-input formula can overstate, too, in two ways.
Not every missed call is a lost job. Some callers are wrong numbers, some are repeat dialers, some are the same person calling twice because they didn't get an answer the first time and are going to call back anyway. The defensible way to think about this is in not every missed call is a lost job — the share of missed calls that were ever going to book is rarely 100%, and discounting for junk and duplicates is the honest move.
Some shops already have partial coverage. If you have an answering service, an AI, or a part-time receptionist, your missed-call count is already lower than it would be. The right comparison is to your current missed-call count, not to a theoretical one with no coverage at all.
If you want a cleaner number, the right adjustment is to discount the missed-call count by 10–20% to account for wrong numbers and non-bookable calls. The formula becomes:
Adjusted monthly loss = (missed calls × 0.85) × close rate × average ticket
That adjustment is more honest than the raw formula. Most owners who use it land within 10% of the unadjusted number anyway, because the under-counting on Bucket 2 calls and the over-counting on Bucket 1 junk calls roughly offset.
Once you have the number, the next question is what to do with it. Three useful comparisons:
Compare to a flat-fee answering service. Ava is $97 first month, then $297/month flat. If your monthly missed-call revenue loss exceeds $297, the answer is the same regardless of the exact number.
Compare to a per-minute live answering service. A live service might run several hundred dollars a month, plus per-minute charges that climb during storm weeks. The flat fee is the easier comparison.
Compare to a part-time hire. A part-time receptionist at $18–$22 an hour, 20 hours a week, runs roughly $1,500–$1,800 a month before taxes and benefits. They cover the day shifts but not nights or weekends.
For a fuller cost breakdown against the alternatives, see answering service cost comparison and the ROI of an AI receptionist.
Here's the full version on one page, ready to copy into a spreadsheet or onto a sheet of paper:
| Input | Your number | Planning figure if you have nothing |
|---|---|---|
| Missed calls per month | _____ | 20 |
| Close rate (decimal) | _____ | 0.50 |
| Average ticket ($) | _____ | $375 |
| Monthly missed-call loss | _ × × __ = $_____ | $3,750 |
| Annualized | $_____ | $45,000 |
Run it once a quarter. The number will move as your call volume changes, your ticket mix changes, and your coverage changes. The point isn't to land on a single number forever — it's to know what your current number is and whether it's going up or down.
A few owners run the calculator and find the number is smaller than they assumed. A few patterns usually explain it.
If your number is small, the conclusion is different: the calculator says you don't have a coverage problem, at least not at this volume. The right move is to recheck the math in three months, and to recheck it again after a busy season. A small number this month can become a large number in May.
The other end is also common. An owner runs the calculator expecting a small number and finds it's much larger. A few patterns explain it.
If your number is larger, the conclusion is also clear: you have a coverage problem worth solving. Compare to $297. The math lands the same way.
A few mistakes that lead to bad numbers.
The calculator is honest when you feed it honest inputs. The pitfalls are usually input errors, not formula errors.
The missed call revenue calculation is three inputs and one formula. The number you get is honest, conservative, and almost always larger than owners assume. Most one- to two-truck shops land in the $2,000–$8,000 a month range once they actually measure.
Ava answers every call 24/7, triages emergencies, captures the details, books the window, and texts you the summary. $97 first month, then $297/month flat. Unlimited calls. No contract. Cancel anytime. Backed by a 30-day "First 10 Leads On Us" money-back guarantee — if Ava doesn't capture your first 10 leads, you get your money back.
Run the calculator with your numbers. If the answer is more than $297 a month, the next step is to hear what your customers would hear when they call.
Call the live demo and have Ava call you now — hear exactly what your customers will hear when they call your shop.