Every plumbing forum has the same argument on page one: flat-rate guys calling hourly guys underpaid, hourly guys calling flat-rate guys salesmen. Both are half right. Here’s the actual math, where each model wins, and the hybrid most 1–5 truck shops quietly end up running.
Hourly: honest, simple, and it caps your best days
Hourly is easy to quote, easy to defend, and customers understand it. The problem is arithmetic: your rate prices your time, not your skill. The drain you can clear in 20 minutes because you’ve cleared four hundred of them bills as 20 minutes. Hourly punishes you for being fast — which is exactly the thing experience makes you.
- Wins when: diagnostic mysteries, open-ended service work, time-and-material commercial accounts, anything where scope is genuinely unknowable.
- Loses when: repeatable jobs (water heaters, disposals, faucet swaps, standard drain calls) where your speed should be margin, not a discount.
Flat-rate: prices the job, not the clock
Flat-rate charges what the job is worth: a 40-gallon gas water heater swap is $X installed, whether it takes you two hours or four. Customers hear certainty (“it’s $1,850, done today”) instead of a taxi meter. Your fast days finally pay like fast days.
- Wins when: standard repairs and installs, competitive bids, customers who fear open-ended bills (that’s most of them).
- Loses when: the job goes sideways — the shutoff that crumbles, the galvanized surprise behind the drywall. Flat-rate only works with a disciplined “found condition” change-order habit: stop, show the customer, price the addition, get the yes in writing before you continue.
The number that decides it: take your last 20 jobs, split them into “repeatable” and “mystery.” Most residential shops find 70–80% repeatable. That share of your work is where flat-rate raises your effective hourly rate without raising a single price — because you stop billing your experience at cost.
The hybrid most small shops land on
- Flat-rate the catalog. Water heaters, toilets, faucets, disposals, standard drain clearing, PRVs, hose bibs — priced as jobs, in a written price book.
- Hourly the unknowns. Leak hunts, remodel rough-ins, “it smells like sewage somewhere” — quoted as a rate with an estimate range.
- A service-call fee either way ($79–$129 in most markets), waived when they proceed with the work. It filters tire-kickers and pays for windshield time.
Whichever you pick, the price book is the business
Flat-rate without a written price book is guessing with confidence. Hourly without one is re-deriving parts pricing in a driveway. Your book — parts, your cost, your sell price, your standard jobs — is the asset. It’s also why we built FieldForge around one: your price book lives in a simple sheet, and when a tech says “swapped the disposal, half hour labor,” the invoice prices itself from your numbers — same price from every tech, every time, no meter running and no napkin math. Free to start.