SMR vs. Traditional Large Reactor Cost Comparison Calculator
Small modular reactors (SMRs) and traditional large reactors represent two different bets on the future of nuclear power: factory-manufactured, standardized modules versus custom, site-built gigawatt-scale plants. This calculator takes a target capacity, an SMR cost per kW, a traditional reactor cost per kW, and the two construction timelines, then reports each option's total project cost, the cost difference as a percentage, and the construction timeline difference in months. It pairs naturally with our SMR Levelized Cost of Electricity (LCOE) Calculator for the full levelized-cost picture and our Nuclear Power Uprate Calculator for the cheapest way to add capacity to an already-licensed plant.
The nameplate generating capacity both options are sized to deliver. 1,000 MW is representative of a large single-unit traditional reactor or a multi-module SMR deployment.
Published estimates for SMR overnight cost range widely, roughly $4,000-10,500/kW depending on source and project maturity.
Recent large traditional reactor projects (like Vogtle Units 3 & 4 in Georgia) have run in the $10,000-16,000+/kW range after cost overruns, though earlier techno-economic estimates cited $7,675-12,500/kW.
SMR developers commonly cite 24-36 months for factory-manufactured module construction and assembly.
Traditional large reactors have historically taken 5-10+ years (60-120+ months) from construction start to commercial operation.
target capacity (MW) × 1000 × SMR cost per kW ($/kW)
target capacity (MW) × 1000 × traditional reactor cost per kW ($/kW)
((traditional reactor cost per kW − SMR cost per kW) ÷ traditional reactor cost per kW) × 100 · $ difference = traditional total − SMR total
traditional reactor construction timeline (months) − SMR construction timeline (months)
SMR per-kW cost projections remain unproven at scale -- no SMR project has yet completed serial (NOAK) construction to validate these figures. The timeline advantage is more consistently supported by current projects than the cost advantage, which several analysts view skeptically given cost overruns on early SMR and traditional reactor projects alike.
Results update live as you type. For planning and field-check estimates — always verify against applicable standards and equipment ratings.
How we calculate this →On paper, a 1,000 MW SMR deployment could cost half as much and finish 4.5 years faster than an equivalent traditional large reactor -- but that comparison rests on SMR cost projections that haven't yet been proven at commercial scale. Real-world experience so far tells a more cautionary story: NuScale's UAMPS project saw costs rise 75% before cancellation, while traditional projects like Vogtle also ran dramatically over budget. The construction timeline advantage from factory-based modular manufacturing is the more consistently supported SMR benefit; the cost advantage remains a projection the industry is still working to prove.
How the SMR vs. traditional reactor cost comparison is calculated
This calculator compares the total project cost and construction timeline of a small modular reactor (SMR) deployment against a traditional large reactor built to deliver the same target capacity. Four quantities tie the comparison together.
SMR Total Project Cost ($) = Target Capacity (MW) × 1000 × SMR Cost per kW ($/kW). Converting the target capacity from megawatts to kilowatts (× 1000) and multiplying by the SMR cost per kW gives the total upfront project cost for the SMR option. At the defaults (1,000 MW and $5,000/kW), that is 1,000 × 1000 × $5,000 = $5,000,000,000.
Traditional Large Reactor Total Project Cost ($) = Target Capacity (MW) × 1000 × Traditional Reactor Cost per kW ($/kW). The same conversion applied to the traditional reactor cost per kW gives the total upfront project cost for the traditional option. At the defaults (1,000 MW and $10,000/kW), that is 1,000 × 1000 × $10,000 = $10,000,000,000.
Cost Difference (%) = ((Traditional Reactor Cost per kW ($/kW) − SMR Cost per kW ($/kW)) ÷ Traditional Reactor Cost per kW ($/kW)) × 100. The percentage cost difference is computed from the per-kW figures rather than the totals so that it reflects the underlying cost-per-capacity gap independent of the target capacity chosen. The accompanying dollar difference is Traditional Total Project Cost ($) − SMR Total Project Cost ($). At the defaults, that is (($10,000 − $5,000) ÷ $10,000) × 100 = 50.0%, with a dollar difference of $10,000,000,000 − $5,000,000,000 = $5,000,000,000.
Construction Timeline Difference (months) = Traditional Reactor Construction Timeline (months) − SMR Construction Timeline (months). Subtracting the SMR timeline from the traditional timeline gives how many months faster the SMR option is projected to reach commercial operation. At the defaults (84 months traditional, 30 months SMR), that is 84 − 30 = 54 months (4.5 years).
Two notes on the model. First, both cost-per-kW figures are overnight capital costs (construction cost in present-day dollars, excluding financing) drawn from published estimates that span very wide ranges -- SMR costs in particular are projections rather than proven serial-production results, and traditional reactor costs reflect recent projects that ran significantly over their original estimates, so the editable fields let you substitute project-specific or source-specific values. Second, this comparison is deliberately narrow: it isolates upfront cost and construction timeline and excludes financing terms, operating cost, capacity factor, revenue timing, and construction risk, all of which materially affect total project economics -- a faster-to-build but similarly-priced option can sometimes offer better overall economics than raw cost-per-kW suggests. Data sources: SMR cost estimates from DOE (Department of Energy) SMR program, NREL (National Renewable Energy Laboratory) techno-economic analyses, and vendor technical specifications; NuScale UAMPS cost history from NuScale public filings and DOE documentation; Vogtle Units 3 & 4 cost data from Georgia Power and NRC filings; traditional large reactor construction timelines from NRC licensing data and historical project records; SMR construction timeline projections from vendor technical specifications and industry analyses; SMR developer status from company announcements and DOE SMR program tracking. Verification: with defaults (1,000 MW, $5,000/kW SMR, $10,000/kW traditional, 30mo/84mo), SMR Total Project Cost = $5,000,000,000, Traditional Large Reactor Total Project Cost = $10,000,000,000, Cost Difference = 50% ($5,000,000,000), Construction Timeline Difference = 54 months.