Price ÷ servings per container — the only fair way to compare two bottles of different sizes.
The metric VitaminDB ranks by. Calculated as priceCurrent / [servingsPerContainer](/glossary/servings-per-container). A 60-count bottle at $18 = $0.30/serving; a 365-count bottle at $72 = $0.20/serving. The cheaper bottle per ml or per gram is often more expensive per actual dose.
Always compare cost per serving, not the front-of-bottle price. Subscribe-and-save and bulk packs typically win on this metric, even when the sticker price feels higher.