HVAC & Plumbing Calculators
Oversized heating and cooling equipment short-cycles, and undersized equipment never catches up. Start with the BTU heating and cooling load, then size a furnace or mini split, ducts, refrigerant line sets and room ventilation. The plumbing set covers radiant floor PEX layouts, pipe size and flow rate, sump pumps, septic tanks and water softeners. Each calculator explains the rule of thumb or formula it uses, and when a full load calculation or a licensed pro should take over.
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All Plumbing & HVAC Calculators
BTU Heating & Cooling Load Calculator
Calculate BTU heating and cooling loads for any room size. Enter room dimensions, insulation, climate zone, and get accurate BTU requirements instantly.
Furnace Sizing Calculator
Estimate furnace BTU output needed based on square footage, insulation and climate zone.
HVAC Duct Size Calculator
Calculate HVAC duct size by CFM and velocity. Find the right round or rectangular duct dimensions for any airflow requirement. Free, instant results.
HVAC Refrigerant Line Set Size Calculator
Calculate the correct refrigerant line set sizes for your HVAC system. Get suction and liquid line diameters, insulation specs, and pressure drop estimates instantly.
HVAC Ventilation CFM Room Air Changes Calculator
Calculate CFM ventilation requirements and air changes per hour (ACH) for any room. Free HVAC tool for homeowners, contractors, and engineers.
Mini Split Sizing Calculator
Find the right ductless mini-split BTU capacity for a room based on size, insulation and climate.
PEX Radiant Floor Heating Layout Calculator
Calculate PEX radiant floor tubing length, spacing, and layout for any room. Free tool for hydronic floor heating design — get accurate tubing estimates instantly.
Pipe Sizing & Flow Rate Calculator
Calculate pipe size, flow rate, velocity, and pressure drop instantly. Free pipe size calculator for water, HVAC, and plumbing — supports multiple pipe materials.
Septic Tank Size Calculator
Calculate the correct septic tank size for your home. Enter bedrooms, occupants, and daily water usage to get the recommended tank capacity in gallons.
Sump Pump Sizing Calculator
Calculate the right sump pump size for your basement. Enter pit dimensions, water inflow rate, and head height to get GPH/GPM requirements instantly.
Water Softener Sizing Calculator
Size a water softener by household size, water hardness (grains) and daily usage.