Macros Calculator Guide - Calculate Your Protein, Carbs & Fat

Tracking macronutrients—protein, carbohydrates, and fat—gives you much more control over your nutrition than simply counting calories. This guide explains how to calculate your optimal macro split for weight loss, muscle building, or maintaining your current weight.

Understanding Macronutrients

Step 1: Calculate Your TDEE

Total Daily Energy Expenditure (TDEE) is how many calories you burn per day. Start with your Basal Metabolic Rate (BMR):

Multiply your BMR by your activity level:

Step 2: Set Your Calorie Target

Step 3: Calculate Your Macros

Protein First

Set protein based on bodyweight, not percentage of calories:

Fat Second

Essential for hormones and health. Don't go too low:

• Minimum: 0.5g per kg (never go below this)
• Moderate: 0.8-1.0g per kg (most people)
• Higher: 1.0-1.5g per kg (low-carb diets)

Carbs Last

Fill remaining calories with carbohydrates:

Common Macro Splits

High-Protein Food Sources

Tracking Your Macros

Popular apps for tracking macros in the UK:

• MyFitnessPal: Largest food database, barcode scanner
• Cronometer: Detailed micronutrient tracking
• Nutracheck: UK-focused database
• MacroFactor: Adapts targets based on progress

Tips for Accurate Tracking

1. Weigh your food: Eyeballing is notoriously inaccurate
2. Log before eating: Not after when you've forgotten details
3. Track cooking oils: A tablespoon of olive oil is 120 calories
4. Check serving sizes: Packets often contain multiple servings
5. Be consistent: Weigh foods the same way each time

Adjusting Your Macros

If you're not seeing results after 2-3 weeks:

Not Losing Weight?

• Reduce calories by 100-200
• Keep protein the same
• Reduce carbs or fat (your preference)

Not Gaining Muscle?

• Add 100-200 calories
• Keep protein adequate
• Add to carbs (fuel training)

Meal Timing

While total daily intake matters most, some timing strategies can help:

• Protein: Spread throughout day (20-40g per meal)
• Pre-workout: Carbs 1-2 hours before training
• Post-workout: Protein within 2 hours (not as urgent as once thought)
• Before bed: Slow-digesting protein (casein) may help overnight recovery

How Macronutrient Calculations Work

Macronutrient calculations begin with determining your Total Daily Energy Expenditure (TDEE), which represents the total number of calories your body burns in a day. TDEE is calculated by first establishing your Basal Metabolic Rate (BMR) using a formula such as the Mifflin-St Jeor equation, which considers your weight, height, age, and sex. The BMR is then multiplied by an activity factor ranging from 1.2 for sedentary individuals to 1.9 for very active people, producing your estimated TDEE.

Once you know your TDEE, macros are divided based on your goals. Each macronutrient provides a specific number of calories per gram: protein provides 4 calories per gram, carbohydrates provide 4 calories per gram, and fat provides 9 calories per gram. For a person with a TDEE of 2,200 calories following a balanced 30/40/30 split (protein/carbs/fat), the calculation produces 660 calories from protein (165g), 880 calories from carbohydrates (220g), and 660 calories from fat (73g). These totals are adjusted up or down based on whether the goal is weight loss (calorie deficit), maintenance, or muscle gain (calorie surplus).

Protein requirements are the most critical macro to get right. Current evidence supports a minimum intake of 1.6 grams per kilogram of body weight daily for individuals engaged in resistance training, rising to 2.2 grams per kilogram for those in a calorie deficit to protect lean muscle mass. For an 80 kg person, this means 128 to 176 grams of protein daily. Once protein is set, the remaining calories are divided between carbohydrates and fats based on personal preference, training demands, and individual tolerance.

Practical Macro Tracking for UK Diets

Tracking macros in the UK is facilitated by the consistent food labelling requirements established under retained EU regulation. Every pre-packaged food product must display a nutrition declaration including energy value, total fat, saturated fat, carbohydrates, sugars, protein, and salt per 100 grams and typically per serving. Popular tracking apps such as MyFitnessPal, Cronometer, and Nutracheck contain extensive UK food databases that include supermarket own-brand products, restaurant meals, and common recipes.

British eating habits present both advantages and challenges for macro tracking. Traditional UK meals tend to be protein-moderate, with typical portion sizes providing 20 to 30 grams of protein per meal. Meeting higher protein targets of 150 grams or more per day often requires deliberate planning, such as including protein-rich foods at every meal and using supplementary protein sources. Cost-effective high-protein UK foods include chicken breast (approximately £5 to £7 per kg), eggs (approximately 15p each), Greek yoghurt, tinned tuna, cottage cheese, and whey protein powder.

The NHS Eatwell Guide provides a framework for balanced nutrition that broadly aligns with moderate macro splits. It recommends that approximately one-third of the diet comes from starchy carbohydrates, one-third from fruit and vegetables, with the remainder split between protein sources, dairy, and small amounts of oils and spreads. While the Eatwell Guide does not prescribe specific macro ratios, its proportions roughly correspond to a 15/50/35 protein/carbohydrate/fat split, which serves as a reasonable starting point for someone new to macro tracking before adjusting based on individual goals.

Frequently Asked Questions

Do I need to track macros to lose weight?

Tracking macros is not strictly necessary for weight loss; a simple calorie deficit is the fundamental requirement. However, tracking macros offers advantages over calorie counting alone. Ensuring adequate protein intake during a calorie deficit preserves muscle mass, which maintains metabolic rate and produces a more aesthetically pleasing result. Many people find that macro tracking also improves food quality naturally, as hitting protein targets while staying within calorie limits encourages choosing nutrient-dense whole foods over calorie-dense processed options.

What happens if I eat too much protein?

For healthy individuals, protein intakes of up to 2.5 grams per kilogram of body weight daily have been shown to be safe in research studies. Concerns about high protein intake damaging kidneys are not supported by evidence in people with normal kidney function. Excess protein is either used for energy, converted to glucose, or in rare cases stored as fat. The main practical issue with very high protein intake is that it can be expensive, may reduce dietary variety, and can cause digestive discomfort in some individuals. People with existing kidney disease should consult their GP before significantly increasing protein intake.

Should I count macros on rest days differently?

Some approaches adjust macros between training and rest days, typically reducing carbohydrates on rest days and slightly increasing fats to compensate. However, for most people, keeping macros consistent daily produces similar results with less complexity. The body does not reset its nutritional needs on a strict 24-hour cycle, and muscle recovery from training continues for 24 to 48 hours after a session. If you prefer to cycle macros, reduce carbohydrates by 25 to 50 grams on rest days and add 10 to 20 grams of fat to maintain similar total calories.

Dr. Sarah Chen, PhD

Research Scientist, Public Health

Sarah holds a PhD in Public Health from the University of Edinburgh and has published research on UK health metrics and obesity trends. She translates complex medical data into practical, accessible guidance for everyday readers.