Which One Should You Use?
Pick by how much of the system is changing. If you are replacing one thing, use the estimator built for it, because size steps, efficiency labels and the extras that get added differ by equipment type. If two or more are changing together, start with the whole-system tool, since doing them at once is cheaper than doing them separately.
What Every Quote Should Itemise
Whichever job you are pricing, ask for the same breakdown so two quotes can actually be compared: equipment model numbers, labor, permit, disposal of the old unit, and any ductwork or electrical work as separate lines. Quotes for identical work routinely differ by thousands on scope alone, and the cheapest one is very often the one that has quietly left something out.
Size It Before You Price It
Every number these tools produce depends on getting the capacity right first, and roughly half of installed systems are oversized. Work out what you actually need with the HVAC load calculator for a whole house, or the AC tonnage calculator for a quicker estimate. Paying for capacity you do not need costs you twice: once at installation, and again on every bill afterwards.
Where the Pricing Comes From
All four tools share one model, so a furnace priced here matches the same furnace inside the whole-system estimator. Every base price and multiplier is published in our cost model methodology rather than hidden, including how efficiency tier and region adjust the result.