Free calculators for the trades
Price jobs and maintenance plans, size equipment and water heaters, check wire, conduit and box fill, and estimate a roof, then print a clean invoice or estimate. Built for HVAC, plumbing, electrical and roofing shops. Every tool runs in your browser.
Pricing calculators
Markup, margin, labor rates, flat-rate prices, maintenance plans and job profitConvert markup to margin and back, or find the price for a target margin. Enter your cost and any one of markup, margin or price.…
Open tool Labor Rate CalculatorWork out your cost per billable hour and labor rate from wage, burden, billable hours, truck, overhead and margin. For HVAC, plum…
Open tool Flat-Rate Price CalculatorPrice three good, better, best options from task hours, labor rate, parts and markup, with a trip fee and rounding. See the profi…
Open tool Maintenance Agreement Price CalculatorPrice an HVAC or plumbing maintenance plan from the cost of one visit, visits a year and your margin. Monthly and yearly price, p…
Open tool Job Profit CalculatorJob costing in one place: price minus labor, materials, subs and permits gives gross profit; minus overhead gives net profit, mar…
Open toolHVAC calculators
Cooling load estimates, BTU conversions and airflowEstimate the BTUs and tons of cooling for a room or area from square feet, ceiling height, sun, people and kitchen use. A rule of…
Open tool BTU to Tons ConverterConvert BTU per hour to tons of refrigeration, kilowatts and MBH, and back. 1 ton = 12,000 BTU/h = 3.517 kW. With a table of comm…
Open tool CFM CalculatorRoom airflow in CFM from air changes per hour, or ACH from CFM, plus the ASHRAE 62.2-2022 whole-home ventilation rate from floor …
Open toolElectrical calculators
Wire size, conduit and box fill, voltage drop, kVA and Ohm's lawFind the smallest copper or aluminum wire for a load from NEC 2023 Table 310.16, with termination rating, derating, the 240.4(D) …
Open tool Voltage Drop CalculatorVoltage drop for copper or aluminum wire, single or three phase, from NEC Chapter 9 Table 8 resistances. Finds the smallest size …
Open tool Ohm's Law CalculatorEnter any two of volts, amps, ohms or watts and get the other two, with the formula wheel showing which formulas were used. Free,…
Open tool Conduit Fill CalculatorConduit fill for THHN and XHHW wire in EMT, rigid, PVC Schedule 40 and 80, from NEC Chapter 9 Tables 1, 4 and 5. Shows % fill and…
Open tool Box Fill CalculatorWork out the cubic inches an electrical box needs under NEC 314.16: conductors, clamps, device yokes, grounds and fittings, again…
Open tool kVA CalculatorConvert kVA to amps and back, single- or three-phase, and kW with power factor. Plus full-load amps of common transformer sizes a…
Open toolPlumbing calculators
Tank and tankless water heater sizingSize a tankless water heater from fixtures used at once and the temperature rise. Gets GPM, gas BTU/h input and electric kW, usin…
Open tool Water Heater Size CalculatorSize a tank or heat pump water heater by first hour rating: add up the busiest hour's showers, dishes and laundry with DOE's peak…
Open toolRoofing calculators
Pitch, roof area, squares, bundles and attic ventilationConvert roof pitch (x/12) to degrees and slope %, and get the pitch multiplier, hip and valley factor and rafter lengths from the…
Open tool Roofing CalculatorEstimate roof area, squares, shingle bundles, underlayment rolls, drip edge, starter and ridge cap from a footprint and pitch or …
Open tool Attic Ventilation CalculatorNet free vent area for an attic under IRC R806.2: 1/150 of the attic floor, or 1/300 with the exception, split into intake and ex…
Open toolInvoices and estimates
Printable documents, filled in on the pageMake a contractor invoice in your browser: your business, the customer, line items, sales tax, discount, deposit and terms. Print…
Open tool Contractor Estimate GeneratorMake a printable contractor estimate: line items, optional add-ons, tax, deposit, a valid-until date and a signature line. Free, …
Open toolStop losing jobs to voicemail
CrewRobin's AI receptionist answers every call, qualifies the job and books it on your calendar, and texts back the calls you miss.