Plate Method Portion Calculator

How it is calculated

Enter the diameter of your plate in centimetres. The tool treats the plate as a full circle and finds its area, A = π × (d ÷ 2)², with d the diameter in cm and A in cm². It then splits that area by the plate-method proportions: half for vegetables, 0.50 × A, a quarter for protein, 0.25 × A, and a quarter for carbohydrates, 0.25 × A. Results are rounded to whole square centimetres. Because the whole plate is used, including the rim, the figures show how big each section looks on the plate, not how much food to weigh. A diameter of zero or less gives no result. Measure straight across the widest part of the plate.

Common mistakes

• Entering the radius instead of the diameter. Because area grows with the square, a 13 cm radius entered as 13 would give a plate one quarter of the real area.
• Entering the plate size in inches. The field expects centimetres, so a 10-inch plate is about 25.4 cm.
• Measuring only the flat food area. The tool uses the full diameter, so if you measure inside the rim, your sections will come out smaller than the figures shown.
• Treating the result as grams or portion weight. It is area on the plate; a heap of food can be tall, so the amount depends on how high you pile it.
• Using the 50/25/25 split as personal medical advice. It is a fixed visual guide, and individual needs should come from a dietitian or doctor.