Anaerobic digesters (ADs) represent a critical technology for managing methane emissions from dairy manure while generating renewable energy revenue. Despite their benefits, widespread adoption among U.S. dairy farms has been limited, primarily due to substantial upfront investment costs and uncertainties in revenue streams influenced by fluctuating environmental policy incentives. This paper assesses the economic viability of different AD technologies: covered lagoon, complete mix, and plug flow digesters, across varying dairy herd sizes and revenue scenarios, including renewable natural gas (RNG), electricity generation, and co-digestion. We apply net present value (NPV) analysis using detailed scenario-based models that incorporate operational costs, fixed capital expenditures, and diverse policy-driven revenues (carbon offset credits, renewable identification numbers, renewal natural gas, and renewable energy credits). Our findings indicate that economic viability significantly depends on herd size, digester type, and revenue streams. Covered lagoon digesters with electricity generation emerge as the most viable for mid-sized farms (600–2,800 cows), whereas large farms (up to 5,000 cows) benefit most from complete mix digesters employing RNG generation. Critical breakeven carbon credit prices necessary for investment viability range from approximately $15 to over $80 per metric ton of CO_ equivalent, decreasing with increasing herd sizes. The analysis also demonstrates the essential role of grants in enabling smaller dairy farms to achieve positive NPVs. Consequently, targeted subsidy programs and stable environmental policy incentives, particularly in carbon markets and RNG initiatives, are imperative for accelerating AD adoption, thereby contributing significantly to achieving climate mitigation goals in the dairy industry.