First install or straight replacement—calculate the full cost to install a garbage disposal including unit, mounting hardware, drain connection, dishwasher knockout, and switch wiring so your kitchen quote is complete before you pull the old unit.
Every garbage disposal ships with a knockout plug in the dishwasher inlet port. If a dishwasher drain connects to the disposal, that plug must be punched out before mounting. If it's not removed, the dishwasher backs up and the customer calls you. It takes 30 seconds with a screwdriver and hammer — and the knockout piece must be retrieved from inside the disposal before running it or it becomes a projectile. This is the most common callback on disposal installs. Document it in your install checklist. Also verify the dishwasher drain has a high loop or air gap per local code — many don't.
InSinkErator's EZ Mount system is proprietary. Moen's Quick Lock system is proprietary. If the replacement disposal matches the existing brand, the mounting assembly stays — you twist off the old unit, twist on the new one, reconnect the drain, and you're done in 30–45 minutes. A different brand means removing the entire sink flange, mounting ring, and gasket, resetting the new mounting system, and resealing. That's an extra 30–45 minutes and a new mounting kit. Ask the brand of the existing unit before pricing. "Same brand as before" is a materially different quote from "any brand."
NEC 422.31(B) requires a means of disconnect within sight of a permanently connected appliance — a disposal. The standard residential solution is a switched outlet (the wall switch controls the outlet). A hardwired disposal also needs a nearby accessible disconnect. If there's no switched outlet under the sink and the customer wants hardwired, you need a disconnect switch — typically a single-gang box near the disposal. If there's no outlet at all, you're adding either an outlet or a circuit. Clarify the electrical situation during the quote call, not after you've dismounted the old unit.
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Get the Plumber's Kit →Garbage disposal installation pricing should include the unit markup, labor time, outlet work if needed, and drain modification if the existing plumbing won't fit. This calculator builds the full job price so you're capturing the value of difficult installations, not just the easy swap-outs. Enter the unit cost, your markup, and labor conditions to get a complete installed price.