Manual J load calculationsmade easy.
Stop guessing air conditioner sizes - get your free, accurate Manual J HVAC load calculation in minutes.
Save Money on HVAC
Oversized AC units waste energy. Undersized units can't keep up. Load Calc Guru make sure you get the right size every time, so you save on both equipment and utility bills.
Accurate Manual J Load Data
We use industry-standard Manual J methodology to calculate heating and cooling loads for every room, factoring windows, insulation, appliances, and climate zone.
Free Basic, Pro Advanced
Unlimited basic Manual J load calculations for free. Upgrade to a Pro plan to use blower door test results, set custom design temperatures, and account for appliances for even more precise results.
Ready to size your HVAC system the right way?
Try our free online Manual J HVAC load calculator and take the guesswork out of air conditioning and heating. Get accurate BTU/hr numbers in minutes, not hours.