Nutrition data and methodology
Nutrition is from the Norwegian Food Composition Table record Celery stalk or stem, raw: 14 kcal, 1.0 g protein, 1.3 g available carbohydrate, 0.0 g fat and 2.0 g fiber per 100 g edible portion. Available carbohydrate excludes fiber; it is not the U.S. total-carbohydrate convention.
The 40 g stalk weight is from Health Canada's Nutrient Value of Some Common Foods table. Only that serving weight is used from Health Canada; all nutrient calculations use the Norwegian record. Other rows are multiples of the reference stalk or explicit weighed portions. Multiply per-100-g values by edible grams divided by 100, then round calories to whole kcal.