Professional-grade sizing tools to help you choose the perfect tankless water heater. No signup required. Get accurate recommendations in under 2 minutes.
Calculate the exact BTU capacity needed based on your climate zone, fixtures, and usage patterns.
Determine the gallons-per-minute (GPM) flow rate you need to run multiple fixtures simultaneously.
See how much money you'll save by switching from a tank to a tankless water heater.
Most tankless water heater buyers undersize or oversize their units because they rely on generic "number of bathrooms" guidelines. Our calculators use real physics and industry-standard formulas to give you accurate, personalized recommendations.
Based on actual BTU calculations, GPM flow rates, and climate-adjusted temperature rise—not vague "2-3 bathroom" estimates.
Get 3-5 product recommendations that match your exact BTU requirement, fuel type, and budget.
No signup, no email required. Get results in under 2 minutes with zero commitment.
See exactly how we calculate your requirements—no black-box algorithms or hidden assumptions.
Step 1: Start with the BTU Calculator to determine your minimum BTU requirement based on climate and fixtures.
Step 2: Use the GPM Calculator to verify your flow rate matches the BTU output (GPM = BTU ÷ 500 ÷ temperature rise).
Step 3: Run the Savings Calculator to see if the upfront cost is justified by your long-term energy savings.
Pro Tip: If your BTU requirement is very high (180K+), consider a dual-unit setup or a commercial-grade tankless water heater instead of maxing out a single residential unit.