Free HVAC Calculators for AC Size, Dehumidifiers, CFM and ACH

Estimate a room air conditioner BTU range from room size, ceiling height, sun exposure, occupants, kitchen heat and insulation, then compare common AC sizes.

Estimate a window AC BTU range and review oversizing, humidity, window fit, CEER/EER, noise, drainage and installation checks before buying.

Estimate portable AC capacity from room inputs and understand SACC, ASHRAE BTU labels, hose losses, exhaust sealing and product label checks.

Convert BTU per hour to cooling tons and thermal kW while keeping room estimates separate from central HVAC system sizing.

Estimate dehumidifier pints per day by room area, dampness level, basement condition, temperature, water intrusion and continuous drain access.

Estimate basement dehumidifier size with dampness level, cool-temperature adjustment, water intrusion checks and continuous-drain planning.

Calculate required CFM from room volume and target ACH for early ventilation planning, with formula, assumptions and code-compliance boundaries.

Calculate air changes per hour from fan CFM and room volume, then compare the result with your target ventilation assumption.

Estimate bathroom fan CFM using area and fixture rules, then check duct length, fan rating, noise, controls and local-code caveats.

Estimate garage ventilation CFM by ACH with explicit boundaries for carbon monoxide, combustion appliances and code-compliant ventilation design.

Estimate room ventilation airflow from room dimensions and target ACH, with the formula and assumptions shown beside the result.

Convert BTU per hour to cooling tons and tons back to BTU per hour for air conditioner capacity comparison.

Convert BTU per hour to thermal kW and explain why thermal capacity is different from electrical input power.

Convert dehumidifier pints per day and liters per day while distinguishing moisture-removal capacity from bucket volume.

Plain-English guide to how many btu per square foot? with formula notes, examples, source context and a related calculator.

Plain-English guide to why oversized ac does not dehumidify with formula notes, examples, source context and a related calculator.

Plain-English guide to portable ac sacc vs btu with formula notes, examples, source context and a related calculator.

Plain-English guide to 30 pint vs 50 pint dehumidifier with formula notes, examples, source context and a related calculator.

Plain-English guide to what size dehumidifier for basement? with formula notes, examples, source context and a related calculator.

Plain-English guide to cfm vs ach with formula notes, examples, source context and a related calculator.

Plain-English guide to bathroom fan cfm guide with formula notes, examples, source context and a related calculator.

Plain-English guide to what is ac tonnage? with formula notes, examples, source context and a related calculator.

Plain-English guide to dehumidifier pints explained with formula notes, examples, source context and a related calculator.

Worked room AC sizing example for a 150 sq ft room with adjustment notes for sun, occupants, ceiling height and kitchen heat.

Worked room AC sizing example for a 300 sq ft room with common-size context and oversizing notes.

Worked room AC sizing example for a 500 sq ft room, including common AC size comparison and humidity caveats.

Portable AC label interpretation for 14,000 BTU units, SACC ratings, hose losses and realistic room-size comparison.

Worked dehumidifier sizing example for a 1000 sq ft basement with dampness, temperature, drain and water-source checks.

Worked bathroom fan sizing example for a small bathroom with area rule, fixture rule, duct length and local-code caveats.