Macro Calculator UK NHS

This independent UK macro calculator converts a daily calorie target into estimated grams of carbohydrate, protein and fat. It is a planning tool for adults and is not an official NHS calculator or an individual dietary prescription.

What is a macro calculator?

Macronutrients are carbohydrate, protein and fat. They provide energy as well as performing other functions in the body. A macro calculator takes an energy target and a chosen percentage split, then converts those percentages into estimated grams per day.

How to use this calculator

1. Enter your daily calorie target.
2. Enter the percentage of calories you want from protein.
3. Enter the percentage from fat.
4. The remaining percentage is assigned to carbohydrate.
5. Select Calculate to convert the split into grams per day.

Formula and UK methodology

The current SACN terminology uses energy conversion factors of 4 kcal/g for protein, 9 kcal/g for fat and 3.75 kcal/g for carbohydrate. The calculator therefore converts each calorie allocation using those UK factors.

SACN states that total carbohydrate should provide an average population intake of at least 50% of energy excluding ethanol, while total fat should provide an average of no more than 35%. Protein requirements are expressed primarily in grams per kilogram of body weight rather than as a population percentage of energy. For that reason, this tool lets you choose a split instead of claiming that one macro ratio is an NHS-prescribed target for everyone.

Worked example

For 2,000 kcal with 20% protein and 30% fat, carbohydrate receives the remaining 50%. Protein is 400 kcal ÷ 4 = 100 g; fat is 600 kcal ÷ 9 = 67 g; carbohydrate is 1,000 kcal ÷ 3.75 = 267 g.

Healthy eating context

The NHS recommends a balanced diet built around a variety of foods, including higher-fibre starchy carbohydrates, fruit and vegetables, dairy or alternatives, and beans, pulses, fish, eggs, meat and other protein foods. Macro numbers do not replace food quality, fibre, micronutrients or overall dietary balance.

Limitations

This calculator does not determine your calorie requirement. Use an appropriate calorie or TDEE calculator first if you need an energy estimate. Population dietary reference values are not individual prescriptions. People with medical conditions, special dietary needs, pregnancy, eating disorders or specialist sports requirements should seek personalised professional advice.

Authoritative sources

• GOV.UK / SACN: energy, fat and carbohydrate recommendations
• NHS: Eating a balanced diet
• GOV.UK: The Eatwell Guide

Related calculators

NHS Calculator · TDEE Calculator NHS · Calorie Deficit Calculator NHS · Calorie Calculator NHS · BMR Calculator NHS · BMI Calculator NHS

FAQs

Does the NHS recommend one macro split for everyone?

No. UK dietary reference values include population-average recommendations for carbohydrate and fat, while protein requirements are generally expressed relative to body weight. Individual needs vary.

How are macro grams calculated?

This calculator allocates your calorie target by percentage and uses UK energy conversion factors: 4 kcal/g protein, 9 kcal/g fat and 3.75 kcal/g carbohydrate.

Should carbohydrates provide 50% of calories?

SACN recommends total carbohydrate at an average population intake of at least 50% of energy excluding ethanol. This is a population recommendation rather than an individual prescription.

Can I use this calculator for a medical diet?

Not as a substitute for personalised advice. If you have a medical condition or special dietary needs, ask an appropriate healthcare professional or registered dietitian.

Disclaimer: This independent calculator is for general information only. It is not an official NHS dietary prescription or medical advice.