{"id":"misun-moisturizer-cost-calculator","version":"1.0.0","reviewedAt":"2026-08-08","purpose":"Convert a moisturizer price and net quantity of contents into cost per application, cost per month and year, and container lifespan, using published finger-tip unit coverage figures.","constants":{"gramsPerFingerTipUnit":0.5,"squareCentimetresPerFingerTipUnit":286,"gramsPerAvoirdupoisOunce":28.349523125,"wholeBodyFingerTipUnits":40.2,"daysPerYear":365.25},"bodyAreas":[{"id":"face-neck","label":"Face and neck","fingerTipUnits":2.5,"sourceRegion":"Face and neck, 2.5 FTU","pairedRegionDoubled":false},{"id":"hands","label":"Both hands","fingerTipUnits":2.4,"sourceRegion":"Hand, 1.2 FTU each","pairedRegionDoubled":true},{"id":"arms","label":"Both arms and forearms","fingerTipUnits":6.6,"sourceRegion":"Arm and forearm, 3.3 FTU each","pairedRegionDoubled":true},{"id":"front-trunk","label":"Chest and stomach","fingerTipUnits":6.7,"sourceRegion":"Front of trunk, 6.7 FTU","pairedRegionDoubled":false},{"id":"back-trunk","label":"Back","fingerTipUnits":6.8,"sourceRegion":"Back of trunk, 6.8 FTU","pairedRegionDoubled":false},{"id":"legs","label":"Both legs and thighs","fingerTipUnits":11.6,"sourceRegion":"Leg and thigh, 5.8 FTU each","pairedRegionDoubled":true},{"id":"feet","label":"Both feet","fingerTipUnits":3.6,"sourceRegion":"Foot, 1.8 FTU each","pairedRegionDoubled":true}],"coverageLevels":[{"id":"thin","label":"Thin layer","multiplier":0.5,"appliesTo":"One product row, not the routine as a whole","provenance":"Site-owned estimate, not a published measurement"},{"id":"standard","label":"Standard coverage","multiplier":1,"appliesTo":"One product row, not the routine as a whole","provenance":"Site-owned estimate, not a published measurement"},{"id":"generous","label":"Generous layer","multiplier":1.5,"appliesTo":"One product row, not the routine as a whole","provenance":"Site-owned estimate, not a published measurement"}],"formulas":{"baseGramsPerApplication":"totalFingerTipUnits * 0.5","gramsPerApplication":"baseGramsPerApplication * productCoverageMultiplier","applicationsPerContainer":"netGrams / gramsPerApplication","daysPerContainer":"applicationsPerContainer * 7 / applicationsPerWeek","costPerApplication":"price / applicationsPerContainer","costPerYear":"price / daysPerContainer * 365.25","costPerOunce":"price / (netGrams / 28.349523125)"},"processing":{"location":"Browser","submittedToServer":false,"storedByCalculator":false,"maximumProductRows":4},"excludedByDesign":["No safety, efficacy, suitability, or medical result","No prefilled prices or package sizes for any third-party product","No volume-to-weight conversion for products declared in fluid ounces","No claim that the estimate matches an individual user's measured consumption"],"designNotes":["Layer thickness is set per product rather than once for the routine. With a single shared thickness, cost per year would always rank products identically to cost per ounce, and the tool could never show the case it exists to show."],"knownLimits":["One finger-tip unit covering 286 cm2 is a mean with a standard deviation of 80 (n = 30), reported as 312 cm2 in males and 257 cm2 in females","The finger-tip unit was developed for topical corticosteroid quantities and is used here only as a coverage yardstick","Coverage multipliers for thin and generous layers are estimates chosen by Misun Health, not measured values"],"sourceLedger":[{"title":"Long CC, Finlay AY. The finger-tip unit: a new practical measure. Clin Exp Dermatol. 1991;16(6):444-447.","url":"https://pubmed.ncbi.nlm.nih.gov/1806320/","identifiers":{"pmid":"1806320","doi":"10.1111/j.1365-2230.1991.tb01232.x"},"supports":"Per-region finger-tip unit counts and the 286 cm2 coverage figure with its variation"},{"title":"Long CC, Finlay AY, Averill RW. The rule of hand: 4 hand areas = 2 FTU = 1 g. Arch Dermatol. 1992;128(8):1129-1130.","url":"https://pubmed.ncbi.nlm.nih.gov/1497374/","identifiers":{"pmid":"1497374"},"supports":"One finger-tip unit equals 0.5 g, the coverage-to-grams conversion"},{"title":"British Association of Dermatologists: Topical corticosteroids","url":"https://www.bad.org.uk/pils/topical-corticosteroids","supports":"Patient-facing definition of a finger-tip unit and the two-flat-hands coverage description"},{"title":"FDA: Cosmetics Labeling Guide","url":"https://www.fda.gov/cosmetics/cosmetics-labeling-regulations/cosmetics-labeling-guide","supports":"Net quantity of contents declared by fluid measure for liquids and by weight for solid, semi-solid, or viscous cosmetics"}],"correctionPolicy":"Review sources quarterly and correct confirmed constant, formula, or citation errors in place with a new version and reviewedAt date."}