How to Calculate Your Calories & Macros (UK Guide)

If you have ever wondered how many calories you actually need, or felt lost when someone mentions "hitting your macros", this guide is for you. It is aimed at UK lifters, runners and everyday gym-goers who want a simple, repeatable way to work out their numbers without a degree in nutrition. Everything below is educational and general; if you have a medical condition or specific dietary needs, speak to a GP or registered dietitian first.

What are calories and macros?

A calorie is a unit of energy. Your food and drink supply energy, and your body spends it staying alive and moving around. Macros, short for macronutrients, are the three components that make up those calories: protein, carbohydrate and fat. Each has an energy value per gram:

• Protein — roughly 4 kcal per gram
• Carbohydrate — roughly 4 kcal per gram
• Fat — roughly 9 kcal per gram

Alcohol also carries energy (about 7 kcal per gram), which is worth remembering if you track. Learning how to calculate macros simply means deciding how many grams of each to aim for so the total matches your calorie target.

Step 1: Estimate your TDEE (maintenance calories)

Your TDEE (Total Daily Energy Expenditure) is the number of calories you burn across a full day, including exercise. Eat around that number and your weight tends to stay stable, so it is often called your maintenance level.

A quick, well-known way to estimate it is to first work out your BMR (Basal Metabolic Rate, the energy your body uses at rest) using the Mifflin-St Jeor equation, then multiply by an activity factor:

• Men: BMR = (10 x weight in kg) + (6.25 x height in cm) − (5 x age) + 5
• Women: BMR = (10 x weight in kg) + (6.25 x height in cm) − (5 x age) − 161

Then multiply your BMR by an activity factor: roughly 1.2 if you are mostly sedentary, 1.375 for light activity, 1.55 for moderate training three to five days a week, and 1.725 if you train hard most days. As an example, an 80 kg, 180 cm, 30-year-old man has a BMR of about 1,780 kcal; at a moderate 1.55 factor his TDEE is roughly 2,760 kcal.

Treat this as a starting estimate, not gospel. The most reliable "calculator" is your own kitchen scales and the bathroom scales over two to three weeks.

Step 2: Set a surplus or a deficit

Once you have a maintenance estimate, adjust it towards your goal:

• Losing body fat: eat below maintenance. A modest deficit of around 300–500 kcal per day is manageable and sustainable for most people.
• Building muscle (bulking): eat above maintenance. A small surplus of around 250–400 kcal per day supports training while limiting excess fat gain.
• Maintaining: eat at maintenance and focus on performance, consistency and recovery.

Give any target at least two to three weeks before judging it. If the scales are not moving in the direction you want after that, nudge your daily calories up or down by 100–200 and reassess. Slower, steadier changes are usually easier to hold on to.

Step 3: Split your protein, carbs and fat

With a calorie target set, divide it into macros. A sensible, flexible approach is to set protein and fat first, then fill the rest with carbohydrate.

Protein

Protein is popular with active people because it contributes to the growth and maintenance of muscle mass. A common everyday target for people who train is around 1.6–2.2 g of protein per kg of bodyweight. For our 80 kg example, that is roughly 130–175 g per day. If you struggle to hit that from food alone, a scoop of protein powder is a convenient top-up. Our guide to how much protein you need per day goes into more detail.

Fat

Fat is an essential part of a balanced diet and helps meals feel satisfying. A practical range is around 0.6–1 g per kg of bodyweight, so roughly 50–80 g per day for an 80 kg person. Adjust within that range to taste.

Carbohydrate

Carbohydrate is your main training fuel. Once protein and fat are set, whatever calories remain go to carbs. Subtract your protein and fat calories from your daily target, then divide the remainder by 4 to get your carb grams. Many lifters place a good portion of their carbs around training. If you want dedicated fuel, browse our carbohydrate supplements.

Step 4: Track it simply

You do not need to weigh every crumb forever. Most people just need enough accuracy to spot trends. A few low-effort options:

• Use a food-tracking app. Log meals for a week to learn the rough macros of the foods you eat regularly, then it gets much faster.
• Weigh the foods that matter. Calorie-dense items like oils, nut butters, cheese and grains are easy to underestimate, so digital kitchen scales and accessories help.
• Build repeatable meals. Once you know a breakfast or lunch fits your targets, you can reuse it without re-logging every time.
• Keep protein anchored. Hitting your protein target each day is usually the habit with the biggest payoff, so plan meals around a protein source first.

Consistency beats precision. Tracking most days and reviewing weekly averages tells you far more than obsessing over a single meal.

Do you need supplements to hit your macros?

No. Whole foods can cover everything. Supplements are simply convenient tools for filling gaps: a shake when you are short on protein, a carb drink for longer sessions, or a bar when you are out and about. Used sensibly they make sticking to your numbers easier, not compulsory. If you are new to all this, our beginner's guide to sports supplements is a good next read.

The bottom line

Estimate your TDEE, set a small surplus or deficit for your goal, anchor your protein, cover your fats, fill the rest with carbs, then track consistently and adjust every couple of weeks. It is a repeatable process, not a one-off calculation. When you want a hand hitting your protein target, explore our full range of genuine protein powders and protein bars and snacks at NE Commerce, with fast tracked UK delivery Monday to Friday.

A quick note

This article is general information, not medical or nutritional advice. Food supplements are not a substitute for a varied, balanced diet and a healthy lifestyle, and should not be used to prevent or treat any illness. Always read the product label, do your own research, and speak to a qualified doctor, pharmacist or registered nutritionist before starting a new supplement — especially if you are pregnant, breastfeeding, under 18, taking medication or managing a health condition.