Nutrition & Food

Calories, macros, diet, cooking ratios and culinary maths

Nutrition & Food formulas help you work out calories, macronutrients, diet targets, cooking ratios, and other everyday food calculations with confidence. Useful for students, exam revision, nutrition studies, fitness planning, and real-world kitchen or health work, these formulas make it easier to compare foods, estimate energy intake, and understand how ingredients and nutrients affect the body.

Food Energy (Atwater)

E = 4P + 4C + 9F + 7A

Total food energy in kilocalories from its macronutrients using the Atwater factors.

Calories from Protein

E_P = 4P

Energy contributed by protein at 4 kcal per gram.

Calories from Carbohydrate

E_C = 4C

Energy from carbohydrate at 4 kcal per gram.

Calories from Fat

E_F = 9F

Energy from fat at 9 kcal per gram — the most energy-dense macronutrient.

Calories from Alcohol

E_A = 7A

Energy from pure alcohol (ethanol) at 7 kcal per gram.

Kilocalories to Kilojoules

kJ = kcal \times 4.184

Convert dietary Calories to the SI energy unit used on many food labels.

Caloric (Energy) Density

D = \frac{E}{m}

Calories per gram of a food — a key idea in filling, lower-calorie eating.

Macro % of Calories

\%_M = \frac{E_M}{E_{total}} \times 100

Share of total energy coming from a given macronutrient.

Protein Requirement (RDA)

P = 0.8 \times m

Recommended daily protein for a healthy adult (grams).

Protein Grams from Calories

g = \frac{r \times C}{4}

Grams of protein for a target protein ratio of the diet.

Glycemic Load

GL = \frac{GI \times C}{100}

Impact of a food portion on blood sugar, combining quality (GI) and quantity.

Net Carbohydrates

C_{net} = C_{total} - F - \tfrac{A}{2}

Digestible carbs after subtracting fibre and half of sugar alcohols.

Percent Daily Value (%DV)

\%DV = \frac{a}{r} \times 100

How much a nutrient in a serving contributes to daily needs.

Weight Change from Energy Balance

\Delta m = \frac{E_{deficit}}{7700}

Approximate body-fat change (kg) from a cumulative calorie deficit or surplus.

Baker's Percentage

\%_i = \frac{m_i}{m_{flour}} \times 100

Every ingredient expressed relative to flour weight — the backbone of bread recipes.

Dough Hydration

H = \frac{m_{water}}{m_{flour}} \times 100

Water as a percentage of flour — controls how wet and open a dough is.

Recipe Scaling Factor

m_{new} = m_{old} \times \frac{n_{want}}{n_{have}}

Rescale each ingredient for a different number of servings.

Brine Salinity

S = \frac{m_{salt}}{m_{salt}+m_{water}} \times 100

Salt concentration of a brine or curing solution by mass.

Yield Percentage

Y = \frac{m_{EP}}{m_{AP}} \times 100

Edible portion left after trimming, relative to the amount purchased.

Food Cost Percentage

FC = \frac{c_{ingredients}}{p_{selling}} \times 100

Ingredient cost as a share of menu price — a core restaurant metric.

Cost per Serving

c_s = \frac{c_{total}}{n}

Total recipe cost divided across the number of servings.

Alcohol by Volume (ABV)

ABV = (OG - FG) \times 131.25

Estimated alcohol content of beer or wine from gravity readings.

Caffeine Concentration

c = \frac{m_{caffeine}}{V}

Caffeine amount per unit volume of a drink.

Water Activity

a_w = \frac{p}{p_0}

Ratio of a food's vapour pressure to pure water — governs microbial spoilage.