The usual version of this math is one multiplication: average ticket times calls missed. Say a plumber charges $480 a job, misses eight calls a week, and works out that he's setting $3,840 on fire every seven days. That number is wrong, and wrong in a direction that hides something useful: the guy quoting $14,000 roof replacements loses less per missed call than the woman washing dogs out of a van.

Four businesses follow and none of them exist. I made up every margin, every close rate, every dollar. They're sketches shaped like real trades. Delete my numbers and write in yours.

The five numbers, and the one everybody skips

Treat your average ticket as the cost of a missed call and you've skipped four steps. A ringing phone is a lottery ticket with four odds stacked in front of it, and then a fifth number almost nobody applies.

  • How many inbound calls are actually prospects. Suppliers, subcontractors, wrong numbers, a customer asking where the invoice went, and eleven robocalls about your vehicle's extended warranty all ring the same phone.
  • How often you close when you do pick up.
  • Contribution margin, not revenue: what's left after the parts and the hours that specific job ate. Leave overhead out, because the rent gets paid whether the phone rings or not.
  • What that customer is worth after the first job, averaged across the ones who stay and the ones you never hear from again.
  • The odds they're gone for good. Most callers who reach voicemail on a service call move on to the next name, so I'll use 0.85. Put in whatever your own call log says.

The plumber, who started this

Six of every ten calls to his line are real work. When he picks up and can be there before dinner he books seven out of ten, because a man standing in two inches of water isn't shopping around. Ticket is $480, contribution margin about 45 percent, so $216. Roughly a third of those customers call him again inside two years, a water heater or a hose bib that split in February, which pushes lifetime contribution to something like $300.

0.6 times 0.7 times 300 is 126. Times 0.85 is 107.

One missed call, $107. Not $480. But he runs two trucks and takes about 60 calls a week, and he's probably missing a quarter of them: after hours, mid-crawlspace, both hands on a wrench. Fifteen calls, call it $1,600 a week. He was wrong about the per-call figure and right that it's serious money.

The groomer, who breaks the pattern

Mobile grooming, one van, one person, $85 a dog. She is the labor, so after shampoo, water, fuel and wear she keeps about $60 of it. Sounds like a rounding error. Except grooming is a subscription nobody calls a subscription. A dog that sticks comes back every six weeks for years. Blend the regulars with the people who book once and vanish, and a new caller is worth maybe 14 visits, so $840 of contribution. Half her calls are new-client inquiries, and she books half of those, because Tuesdays are full and some people only wanted a price.

0.5 times 0.5 times 840 is 210. Times 0.85 is about 178.

She's also the worst-placed person here to answer a phone: wet hands, clippers running, and a spaniel on the table who will absolutely jump.

The roofer, whose big number is lying to him

A full tear-off and replacement runs $14,000. Margin 25 percent, so $3,500 of contribution. That's thirty times the plumber's ticket and a hundred and sixty times a dog wash, and it barely matters. Look at the funnel. Just over half his inbound calls are homeowners at all. The rest are suppliers, subs, adjusters, and people who want a free bid to wave at the contractor they already chose last Thursday. Of the real ones, 60 percent let him up on the roof. Of those inspections, one in five turns into work.

0.55 times 0.6 times 0.2 times 3,500 is 231. Times 0.85 is about 196.

So a $14,000 roof and an $85 bath on a labradoodle land within twenty dollars of each other. And he gets no second bite. He re-roofs that house in 2050, if he's still climbing ladders and she hasn't moved to Arizona.

The mechanic, and the multiplier that gets abused

An independent shop with three bays. Average repair order $420, margin around 48 percent, so $202. This is where people cheat. They picture the loyal customer with nine repair orders over four years, multiply 202 by nine, get $1,818 and announce that every missed call costs the shop a mortgage payment. Don't. Most first-timers are one and done. Average across everyone who has ever pushed that door open and four visits is closer to honest, so $808. Say 65 percent of his calls are real prospects and he books 60 percent of those.

0.65 times 0.6 times 808 is 315. Times 0.85 is about 268.

The least dramatic job on the list has the most expensive silence. Retention does that.

Six months of it, and what the forty thousand misses

Annual numbers make this look worse and also less true, so try one business over a half year. Say a two-truck septic outfit outside Springfield, average job $385, about forty calls a week once the ground thaws, and an owner who answers when he isn't under a truck or standing in a back yard with a probe rod. He misses a third, so thirteen calls a week ring out. A third of those wanted work done, so four jobs and about $1,540 a week, roughly $6,600 a month. Six months is just under $40,000. That's the number everybody quotes, and it's the smallest one here.

A septic tank gets pumped every three to five years for as long as the house is standing, and the same household calls back for a riser, a filter swap, or the 2 a.m. backup on Thanksgiving with fourteen people in the kitchen. Every unanswered call in March hands that whole run to whoever picked up on the second ring. The March books lose one job. The 2034 books lose a route, and nobody writes that one down. The caller who got through to somebody else also leaves that company a Google review two days later, because people whose Thanksgiving just got rescued tend to say so in public. After six months the other outfit has thirty-odd fresh reviews and you have four.

Then comes the part that actually hurts. Around month three, revenue is soft and the owner does the sensible thing: bumps the ad budget, pays someone eight hundred a month for SEO. Calls go up, and so does the share that goes unanswered. If a third go unanswered at forty a week, a third go unanswered at eighty. His cost per booked job just doubled. The leak scales with the spend. Fixing the phone first would have made every marketing dollar worth more.

Where this arithmetic falls apart

Annualizing it. The groomer can't wash 40 dogs a week however fast she answers, so once her calendar is full, a missed call costs her only the gap between the dog she got and the dog she'd rather have had. The plumber's weekly figure holds right up until it turns into a third truck and a hiring problem. Any rep who hands you a $200,000 annual number has multiplied straight past your own capacity and is betting you won't check it against your diary.

Use the per-call number as a spending limit instead. It tells you what answering is worth to you specifically, which is the only version of this that survives contact with a bank account.

What answering costs against that

Rocketship answers the number you already have, through call forwarding. It knows your hours, services and prices, and it books into your Google Calendar while you're flat on your back under a sink. Launch is $24.99 a month ($20.83 billed yearly), a dedicated line is $5 a month extra, so call it $30 a month, or about $360 a year. One recovered call is worth about $268 to the mechanic, so a bit under nine months of it, and two recovered calls cover the year. For the groomer one recovered call, $178, covers about six months.

Check minutes before you assume it fits, though. Launch includes 30 voice minutes a month, which is roughly a dozen two- to three-minute calls. The plumber missing fifteen calls a week is closer to 60 calls a month, so he'd look at Frontier (80 minutes, $79 a month) or Mission Control (150 minutes, $149 a month with a dedicated number included). Phone coverage is one step in a longer chain. The same product finds buyers, emails them from your own Gmail, follows up and books the meeting, so the ad money you're already spending lands on something that answers.

Work out your own five numbers tonight, on paper, honestly. If the answer comes back $40, ignore every phone system anyone has ever tried to sell you. If it comes back $268, you've been funding somebody else's truck payment for years and never once seen the invoice. A missed call costs you the customer and the second job. Rocketship finds the buyers, emails them from your own Gmail, follows up, and books the meeting on its own. Plans that get you customers start at $24.99 a month (Launch), and every monthly plan starts with a 7-day free trial, card required. Answering your existing number is included; a dedicated line is $5 a month.