The data behind every calculator, the exact formulas we apply, and the limits you should keep in mind when using any online estimate.
Every calculator starts from a published low-to-high national price range for a specific job, taken from established cost-guide research: Angi and HomeAdvisor for home services, HomeGuide for pool maintenance, roofing, electrical work, house cleaning and lawn mowing, AutoZone and SoFi for auto service, Housecall Pro for commercial cleaning, Kitchen Repair Hub for commercial kitchen equipment repairs, National Hood Cleaners and Grease Management for kitchen exhaust and grease trap service, OxMaint and Kahn Mechanical for commercial HVAC replacement, and Plumbing Price Guide for repiping. The source for each range is cited and linked directly beneath the pricing table on that calculator's page. We use the published ranges as they are. We don't invent figures or average in unverified quotes.
A national range like "AC repair: $450 to $2,000" is too wide to be useful on its own, so each calculator asks the one or two questions that move the price most. There are three ways this works, depending on the service:
The plumbing calculator also offers an emergency / after-hours option, which multiplies the range by 1.5 to reflect the premiums many plumbers charge outside business hours.
Some calculators build a total from several published ranges, the way a contractor's quote does. The repair you choose sets the main range. Optional items you check, such as a diagnostic fee, an after-hours surcharge, refrigerant by the pound, a crane, permits or drywall patching, each add their own published low and high. On the commercial HVAC estimator, per-unit items (the installed unit, curb, electrical, ductwork, roof work and refrigerant recovery) are multiplied by the number of rooftop units, while per-job items like the crane and permits are added once. Hood cleaning and grease trap estimates multiply the per-visit range by the number of services per year for the schedule you pick. Results are rounded to the nearest $5 under $1,000, $10 under $10,000 and $100 above that.
Where a source gives only an hourly rate, we say so on the page. For example, the furnace calculator's emergency option adds the difference between published emergency and standard labor rates for a typical one-to-two-hour repair.
If you choose a state, the estimate is multiplied by that state's Regional Price Parity (RPP), published by the U.S. Bureau of Economic Analysis. RPPs measure how expensive goods and services are in each state relative to the national average, which is set to 100. For example, California's RPP of about 110.7 raises an estimate by about 10.7%, and Mississippi's RPP of about 87.0 lowers it by about 13%.
RPP is a broad, statewide cost-of-living measure, not a trade-specific labor rate. Prices within a state still vary a lot between cities and rural areas, and some trades vary more than the overall cost of living. We use it because it's an official, transparent adjustment, and we label it clearly on every result instead of presenting it as a local quote.
Use the estimate as a budgeting range and a sanity check on quotes, never as a guaranteed price. See our disclaimer for more.
Every calculator shows the date it was last reviewed. We re-check each range against its source at least twice a year and update the calculator and its tables together. If you're a contractor or homeowner and a range doesn't match what you're seeing, please tell us through our contact page. Corrections with a source or recent invoices are especially helpful.