Per Gram
Carbon cost of protein · kg CO₂e per 100g protein
Scan a barcode or photograph your grocery receipt. Per Gram works out the carbon cost of the protein you bought, kilograms of CO₂e per 100g of protein, and pays you in B3TR for the low-carbon ones. Free, and the quantity always comes off the receipt rather than from anything you type.
The weight of the food, not the protein in it. A standard tin of tuna is about 5 oz; a tub of powder is on the label.
Scan everything first, then photograph the receipt once. The receipt supplies the quantities. That is the whole point of it.
Paper or digital. A till receipt, or the order page from a pickup or delivery shop. Photograph the screen, or pick a saved screenshot. A receipt counts once here, so every copy after the first is refused, whoever is holding it.