HVAC + Electrical
Every Intry Tool
Pick your trade, then the job you are standing in front of. Calculators are the buttons; charts and guides are listed under them. No login, no email, no ads.
On this pageElectrical directoryHVAC directoryPricing & marginThe platform
Electrical Calculators
NEC 2023 load capacity, wire and breaker sizing, conduit and boxes, EV and heat-pump circuits, plus the reference charts and code guides. Organized by the job.
Open the electrical hubHVAC Calculators
Equipment sizing, ductwork and airflow, charge and diagnostics, the R-454B and R-32 changeover, and nameplate decoding. Organized by the job.
Open the HVAC hubElectrical: pick the job
Every code calculation names the NEC table and section it used. Open the electrical hub.
Guides & answersWhat size breaker do I needWhat size ground wireHow many amps does an appliance useHow many outlets on a circuitWire size for appliancesMini split breaker sizeMrCool mini split breaker sizeA2L (R-454B) changeout circuit checkCopper vs aluminum wireTHHN vs THWN
Charts & NEC tablesConduit fill chart (THHN/EMT)Offset multiplier chart90 degree deduction chart
Guides & answersWhat size conduit for a wire pullConduit types (EMT, PVC, RMC, more)
HVAC: pick the job
Load sizing, airflow, charge diagnostics, and the A2L transition, each number cited to its source. Open the HVAC hub.
Charts & tablesBTU per square foot chartHeat pump capacity at 5F chart
Guides & answersWhat size air conditioner do I needHow many BTU to heat a houseWhat size mini splitWhat size garage heater
Charts: PT tablesR-410A PT chartR-454B PT chartR-32 PT chartR-22 PT chartR-134a PT chartR-404A PT chartR-407C PT chartR-448A PT chartR-449A PT chartR-290 (propane) PT chartSuperheat & subcooling chart
Guides & answersHow to calculate superheatNormal superheat & subcooling valuesSubcooling on a heat pump
Charts & tablesA2L properties (GWP & class)
Guides & answersR-410A phase-out & timelineR-454B vs R-410AR-32 vs R-410AR-32 vs R-454B
The money side: pricing & margin
Service Pricing Calculator
Calculate your true hourly rate based on income goals, overhead, taxes, and billable hours. Includes trade-specific benchmarks.
Markup vs Margin Calculator
Convert between markup and margin instantly. See both percentages side by side with trade-specific benchmarks for contractors.
The Intry platform
Everything around the calculators: run any tool in your AI assistant, keep your readings as one job across visits, embed a calculator on your own site, and see how the numbers are checked against their sources.
PlatformThe Intry app (keep readings as one job)Run these in your AI (ChatGPT, Claude, Cursor)Intry Verified (how the numbers are checked)Free calculators for your website (embed)
Frequently Asked Questions
Are these tools really free?
Yes. Every tool is open to anyone: no login, no email gate, no ads. We build these tools because they help trade contractors do better work, and we think that earns trust. Accuracy and usefulness are the whole point; the site supports itself.
How accurate are the electrical calculators?
All electrical calculators reference the National Electrical Code (NEC) 2023 edition with specific table and section citations. Values are cross-referenced against published manufacturer data from Southwire, Greenlee, and Klein. If you spot an error, contact us. Accuracy matters.
Do I need to create an account to use these tools?
No. Every tool works instantly in your browser with zero signup. You can bookmark results or use the share button to generate a link with your inputs pre-filled.
Pick a calculator and get to work.
Wire sizing, conduit bends, BTU loads, pricing math: every tool cites its source so you can check the numbers yourself. No login, no email, ever.