Enhanced Geothermal System (EGS) Well Cost Calculator
Enhanced Geothermal Systems (EGS) unlock heat from hot, dry rock by drilling wells and engineered fracture networks where natural permeability is too low for conventional geothermal production -- and the drilling program is typically the single largest capital cost in any EGS project. This calculator takes the number of successful production wells a project needs, the drilling cost per well, and the well success rate, then reports how many wells must actually be drilled (accounting for dry holes) and the total drilling program cost. It pairs naturally with our planned Geothermal Power Plant Output Calculator for the generation those wells support, and our planned Geothermal LCOE Calculator for how this drilling cost flows through to levelized cost of electricity.
The number of commercially productive production wells the project requires to meet its design thermal output.
Fervo Energy has publicly demonstrated reducing EGS horizontal well drilling costs from $9.4 million to $4.8 million per well at its Cape Station project through drilling efficiency improvements -- a real, documented cost reduction, not a projection.
Geothermal drilling studies commonly cite roughly a 20% dry-hole (unsuccessful well) rate -- meaning about 1 in 5 wells drilled doesn't perform as needed and must be accounted for in program-level cost planning.
number of successful wells needed ÷ (well success rate (%) ÷ 100)
wells required accounting for success rate × drilling cost per well ($)
This calculator estimates production drilling program cost at a planning level using a single average success rate. Actual EGS programs see well-by-well variation in outcome and cost, and success rates typically improve within a resource area as subsurface characterization matures -- consult a qualified reservoir engineer and drilling specialist for project-specific cost estimation.
Results update live as you type. For planning and field-check estimates — always verify against applicable standards and equipment ratings.
How we calculate this →Drilling risk isn't a rounding error -- it's a real cost multiplier that has to be planned for upfront. Needing 40 successful wells at an 80% success rate actually means drilling 50 wells total, pushing total program cost to $240 million even at Fervo's dramatically reduced $4.8 million per-well cost (down from $9.4 million just a few years ago). This is exactly why geothermal drilling cost reduction and improved success rates through better subsurface characterization are treated as equally important levers for project economics -- a cheaper well that still fails 20% of the time doesn't fully solve the cost problem on its own.
How EGS well cost is calculated
This calculator estimates the total drilling program cost for an Enhanced Geothermal System (EGS) production well campaign by first inflating the number of successful wells needed to account for wells that turn out to be dry or underperforming, then multiplying that risk-adjusted well count by the drilling cost per well. Two quantities tie the calculation together.
Wells Required Accounting for Success Rate (wells) = Number of Successful Wells Needed ÷ (Well Success Rate (%) ÷ 100). Not every well drilled becomes a productive producer -- some fail to achieve sufficient permeability or flow -- so the number of wells that must actually be drilled is the number of successful wells needed divided by the success rate expressed as a fraction. At the defaults (40 successful wells needed and an 80% success rate), that is 40 ÷ 0.80 = 50 wells.
Total Drilling Program Cost ($) = Wells Required Accounting for Success Rate × Drilling Cost per Well ($). Multiplying the risk-adjusted well count by the all-in drilling cost per well gives the total capital cost of the production drilling campaign. At the defaults (50 wells and $4,800,000/well), that is 50 × $4,800,000 = $240,000,000.
Two notes on the model. First, the well success rate is the single most consequential input alongside per-well cost, and it is applied as a single program-average figure -- real EGS programs see well-by-well variation in outcome, and success rates typically improve within a given resource area as data from earlier wells informs better targeting and stimulation design for subsequent wells, so the editable field lets you substitute a project-specific or area-specific figure. Second, this calculator covers production well drilling program cost only and does not model exploratory or appraisal wells (drilled earlier to characterize a resource before committing to a full production campaign), well stimulation and reservoir creation costs, surface plant and power block costs, or operating costs -- all of which are separate cost categories not included here. For the power output those production wells ultimately support, see the planned Geothermal Power Plant Output Calculator; for how this drilling cost flows through to levelized cost of electricity, see the planned Geothermal LCOE Calculator. Data sources: EGS horizontal well drilling cost reductions ($9.4M to $4.8M per well) from Fervo Energy's Cape Station project public reporting; geothermal drilling dry-hole / success rate benchmarks (~20% dry-hole rate) from DOE (Department of Energy) and geothermal drilling studies; EGS drilling and subsurface characterization methodology from DOE Geothermal Technologies Office and National Renewable Energy Laboratory (NREL) technical reports. Verification: with defaults (40 successful wells needed, $4,800,000/well, 80% success rate), Wells Required Accounting for Success Rate = 50 wells, Total Drilling Program Cost = $240,000,000.