The basic math, with real examples
Divide price by weight in grams, multiply by 100. Klatch's Don Julian Geisha Natural: $39.95 ÷ 170 g = $23.50 per 100 g (checked September 30, 2026). Boquete Coffee Traders' Carmen Estate Geisha: $67 ÷ 225 g = $29.78 per 100 g (checked September 16, 2026). Don Pachi Estate Java Natural: $33 ÷ 150 g = $22.00 per 100 g (September 16, 2026). Sigma Coffee UK's Boutet Natural Gesha: £24 ÷ 340 g = £7.06 per 100 g (September 30, 2026). Café Suarez Blend: $12 ÷ 200 g = $6.00 per 100 g (September 30, 2026). Café Palo Alto: $18.99 ÷ 425 g = $4.47 per 100 g (September 30, 2026).
Four rules that keep the comparison honest
First, compare within a currency: we list prices in their original currency ($, £, €, RM) and convert only with a dated exchange-rate source. Second, exclude shipping and taxes unless the seller says they're included — a flat $33 DHL box to the US changes the math for small orders. Third, don't compare green with roasted directly: green coffee is priced per kilogram or pound (Sey reports direct green prices of $200–$319.64 per kg for its top Panama lots), and roasted weight after roast loss isn't one-to-one. Fourth, compare like with like: a 15 g auction-bottled lot (Finca Sophia FS-06 at RM400) is a collectible format, not a price benchmark.
What per-100g pricing is good for
It tells you whether you're paying for scarcity or for packaging. A $29.78-per-100g Geisha and a $23.50-per-100g Geisha are in the same market; a $6-per-100g blend is buying you Panama terroir without the variety premium. Use the price database to check auction context, and the date on each listing to judge how fresh the observation is.