What specific input metrics do I need to provide to get an accurate B2B marketing ROI calculation?

Accurate B2B marketing ROI requires costs, attributable revenue, funnel conversion rates, sales-cycle timing, and attribution rules defined consistently across systems and timeframes. At The Starr Conspiracy (TSC), the minimum input set includes: fully loaded program costs (media, tools, agency, labor), pipeline and revenue by source, lead→MQL→SQL→opportunity→closed-won conversion rates, average deal size, and average sales-cycle length in days. TSC’s Chief Experience Officer Racheal Bates notes that “ROI disputes usually come from inconsistent attribution windows and missing cost categories, not bad math.” For example, if your average sales cycle is 180 days, your ROI window must cover at least that period plus a defined lag (e.g., 30 days) to avoid undercounting revenue.