Assumptions and sources. Mortality: SSA 2023 period life table (Trustees Report 2026), blended 60% female / 40% male — VERIFIED (ssa.gov/oact/STATS/table4c6.html). Non-death attrition is ILLUSTRATIVE: frailty/homebound/move to care 1%/yr under 75, 3% at 75–84, 6% at 85–89, 10% at 90+; caregiving withdrawal +1%/yr ages 55–84; moves/other 1.5%/yr all ages. Anchors: ~5.6% of community-dwelling 65+ are homebound (Ornstein et al., JAMA Intern Med 2015); physical limitations predict 16% lower regular attendance 4 years later (PLOS One 2022). Age distribution: bell curve around the average (spread narrows as average rises); new joiners spread around their average age (SD 15, ages 0–90). Each joiner counts as one attendee. "Coasian Floor" = (pastor compensation + facility G&A) ÷ giving per attendee — the attendance needed to cover a full-time pastor and building; it ignores program costs, benevolence and endowment. Giving is assumed proportional to attendance. Illustrative planning tool, not a forecast. Prepared for the Mount of Olives Health Ministry (CareWave).