収縮計算機

The Shrinkflation Calculator quantifies the hidden price increase when a product's package shrinks but its price stays the same — a stealth strategy manufacturers use to maintain price points during inflation while reducing per-unit value. Calculator computes old price-per-unit, new price-per-unit, and the effective percentage increase. Classic examples: cereal box dropping from 16 oz to 14 oz at the same price = 12.5% effective price increase; toilet paper rolls going from 264 sheets to 244 sheets = 7.6% increase; chip bag dropping from 10 oz to 9 oz = 10% increase. Shrinkflation appears across consumer packaged goods: cereals, snacks, ice cream, frozen pizza, candy bars, paper products, cleaning supplies, even pet food. Pringle's chips went from 5.2 oz to 5.0 oz (4% increase) in 2022. Folgers coffee went from 51 oz to 43.5 oz (17% increase). Wheat Thins went from 9.1 oz to 8.5 oz (7% increase). Researchers at the Federal Reserve estimate shrinkflation accounted for ~8% of effective grocery inflation during 2020–2023, partially explaining why CPI measurements understate consumer experience. Formula: Effective Increase % = ((New $/Unit − Old $/Unit) / Old $/Unit) × 100. This is the price increase felt per actual quantity of product purchased — different from sticker price comparison which would show 0% change. The calculator outputs both old and new per-unit prices alongside the effective increase to make the math transparent and verifiable. Who benefits from awareness: home shoppers who can switch to store brands (typically the least affected by shrinkflation), batch buyers who lock in current sizes, and consumer advocates documenting industry patterns. The grocery industry argues shrinkflation is preferable to sticker shock because consumers psychologically prefer 'same price, slightly less' over 'same amount, higher price.' Critics counter that this is deceptive — most shoppers don't notice 5–10% size changes but would notice equivalent price increases. Mandatory disclosure laws (France's 'shrinkflation labels' since 2024) require retailers to flag products that shrank.

PrimeCalcPro provides professional-grade tools trusted by businesses and academics.

1. 1Step 1 — Enter old size and old price (check old packaging, archive.org for past listings, or shrinkflation databases)
2. 2Step 2 — Enter new size and new price (current store shelf)
3. 3Step 3 — Select unit (oz, g, mL, count — make sure both sizes use the same unit)
4. 4Step 4 — Calculator computes old $/unit = Old_P / Old_S and new $/unit = New_P / New_S
5. 5Step 5 — Computes effective increase = ((New $/unit − Old $/unit) / Old $/unit) × 100
6. 6Step 6 — Computes size reduction percentage for reference
7. 7Step 7 — Output labels result as Within Inflation Range or Likely Shrinkflation

• !Comparing total prices without checking unit count (4-pack vs 6-pack of same product)
• !Forgetting size shrinks are often only 5–10% — small but cumulative across many products
• !Not using shelf unit pricing tags (legally required in most US states)
• !Assuming premium brands are immune — they actually shrinkflate more often than store brands
• !Confusing portion-control packaging (genuine convenience product) with shrinkflation (same product, less of it)