Size the ground loop for a geothermal (ground-source) heat pump: total bore footage, number and depth of vertical boreholes (or horizontal trench length), loop-field cost, and estimated annual heating savings versus conventional systems. A fast planning estimate for U.S. homes.
Borehole & loop-array sizing
A geothermal (ground-source) heat pump exchanges heat with the stable temperature of the earth through a buried ground loop. Sizing that loop is the make-or-break design step: too short and the system can't move enough heat, hurting efficiency and longevity. The loop length needed depends on the heating/cooling load (in tons) and the thermal conductivity of your soil — typically 150–250 ft per ton for vertical boreholes and 400–600 ft per ton for horizontal trenches.
For a vertical system, total bore footage is divided across boreholes drilled to a maximum depth (often 200–400 ft), spaced about 15–20 ft apart. A 4-ton home at 200 ft/ton needs roughly 800 ft of bore — about three to four 250-ft boreholes. Horizontal loops cost less to install but need much more land. Because geothermal heat pumps deliver 3–5 units of heat per unit of electricity (COP 3–5), operating costs run far below conventional electric or propane heating. This tool estimates your loop length, borehole count, loop-field cost, and yearly savings.
150–250 ft/ton, drilled deep. Best where land is limited; higher drilling cost per foot.
400–600 ft/ton in shallow trenches. Cheaper to install but needs lots of open land.
Geothermal moves 3–5× more heat than the electricity it uses, slashing heating bills.
Residential geothermal qualifies for a federal clean-energy tax credit, improving payback significantly.
Geothermal (ground-source) heat pumps are the most efficient way to heat and cool a U.S. home, and homeowners search "geothermal heat pump cost," "geothermal loop sizing," and "geothermal tax credit 2026" while weighing the investment. The biggest cost driver is the buried ground loop, and getting its size right is critical. This calculator estimates total bore footage, the number and depth of vertical boreholes (or horizontal trench length), loop-field cost, and your annual heating savings.
Residential geothermal qualifies for a 30% federal clean-energy tax credit on the entire installed system, dramatically improving payback versus propane, heating oil, or electric-resistance heat. With a COP of 3–5, a geothermal system delivers three to five units of heat per unit of electricity — enter your tonnage and soil type to size the loop and estimate savings.
A 4-ton home using a vertical loop at 200 ft/ton needs about 800 feet of bore — roughly three to four 250-foot boreholes. At $15/ft the loop field is about $12,000; with the heat pump the installed system runs higher, but the 30% federal tax credit applies to the whole project, and operating savings versus electric-resistance heat are significant.
U.S. homeowners, builders, and HVAC contractors planning a geothermal (ground-source) heat pump and needing to size the ground loop and estimate loop-field cost and energy savings.