Macro Calculator

About Macro Calculator

How Is the Calculation Done?

The calculator works in three steps:

1. Calculate TDEE using the Mifflin-St Jeor equation (age, sex, height, weight, activity level)
2. Adjust for goal: subtract 500 cal for fat loss, add 500 for muscle gain, or keep as-is for maintenance
3. Split into macros using the selected diet profile's percentage ratios

Worked example: Male, 30, 80 kg, 180 cm, moderately active, fat loss goal, balanced diet

1. BMR: (10 x 80) + (6.25 x 180) - (5 x 30) + 5 = 1,780 cal
2. TDEE: 1,780 x 1.55 = 2,759 cal
3. Fat loss target: 2,759 - 500 = 2,259 cal
4. Balanced split (30/40/30): Protein 30% = 677 cal = 169g, Carbs 40% = 904 cal = 226g, Fat 30% = 678 cal = 75g

Diet Profile Comparison

Profile	Protein	Carbs	Fat	Best For
Balanced	30%	40%	30%	General health, sustainable long-term eating
High-Protein	40%	35%	25%	Muscle building, preserving muscle during fat loss
Low-Carb	40%	20%	40%	Blood sugar management, people who feel better on fewer carbs
Keto	30%	5%	65%	Ketogenic diet followers, epilepsy management
Custom	You set	You set	You set	Any specific dietary approach

What Each Macronutrient Does

Macro	Cal/gram	Primary Function	Key Sources
Protein	4	Muscle repair, enzyme production, immune function	Meat, fish, eggs, dairy, legumes, tofu
Carbohydrate	4	Energy (especially for brain and muscles), fibre	Grains, fruit, vegetables, rice, potatoes
Fat	9	Hormone production, vitamin absorption, cell membranes	Oils, nuts, avocado, butter, fatty fish

No macronutrient is inherently "bad." All three are essential. The ratio matters because it affects how you feel, perform, and progress toward your goals.

How Much Protein Do I Need?

Protein requirements depend on your activity level and goal:

Goal / Activity	Grams per kg of Body Weight	Grams per lb of Body Weight
Sedentary adult (general health)	0.8 g/kg	0.36 g/lb
Recreational exerciser	1.0 - 1.2 g/kg	0.45 - 0.55 g/lb
Endurance athlete	1.2 - 1.4 g/kg	0.55 - 0.65 g/lb
Strength training / muscle gain	1.6 - 2.2 g/kg	0.7 - 1.0 g/lb
Fat loss (preserving muscle)	1.8 - 2.4 g/kg	0.8 - 1.1 g/lb

The 0.8 g/kg RDA is the minimum to prevent deficiency, not the optimal amount for active people. Research consistently shows that higher protein intake (1.6-2.2 g/kg) supports better muscle retention during fat loss and better muscle growth during training. For a protein-focused calculator, the Protein Calculator provides more detailed recommendations.

Thermic Effect of Each Macro

Your body uses energy to digest food. The amount varies by macronutrient:

Macro	Thermic Effect	Net Calories per Gram	Practical Impact
Protein	20-30%	~2.8 - 3.2	100 cal of protein costs 20-30 cal to digest
Carbohydrate	5-10%	~3.6 - 3.8	100 cal of carbs costs 5-10 cal to digest
Fat	0-3%	~8.7 - 9.0	100 cal of fat costs 0-3 cal to digest

This is one reason why high-protein diets have a slight metabolic advantage - you effectively absorb fewer net calories from protein than from the same calorie amount of carbs or fat.

Sample Macro Targets by Body Weight

Body Weight	Fat Loss (2,000 cal, 40/30/30)	Maintenance (2,500 cal, 30/40/30)	Muscle Gain (3,000 cal, 30/45/25)
60 kg / 132 lbs	200g P, 150g C, 67g F	188g P, 250g C, 83g F	225g P, 338g C, 83g F
75 kg / 165 lbs	200g P, 150g C, 67g F	188g P, 250g C, 83g F	225g P, 338g C, 83g F
90 kg / 198 lbs	200g P, 150g C, 67g F	188g P, 250g C, 83g F	225g P, 338g C, 83g F

Note that the macro grams are driven by your calorie target and percentage split, not directly by body weight. However, checking that your protein grams per kg of body weight falls in the right range for your goal is a good sanity check.

Tracking Macros in Practice

Tip	Why It Helps
Prioritise hitting protein first	Protein is the hardest macro to hit and the most important for body composition
Plan protein with each meal	Distributing protein across 3-5 meals supports muscle protein synthesis
Fill remaining calories with carbs and fat	Once protein is set, carb/fat ratio is less critical for most people
Allow +/- 5-10g flexibility	Perfect accuracy is unnecessary and adds stress
Weigh food with a kitchen scale	Portion estimation can be off by 20-50%
Reassess every 4-6 weeks	As weight and activity change, macros should change too

Protein Quality: PDCAAS vs DIAAS

Not all protein sources are equal. Two scoring systems are used to rate protein quality based on how well the body can digest and use the amino acids:

PDCAAS (Protein Digestibility-Corrected Amino Acid Score) was adopted by the WHO in 1991. It scores protein from 0 to 1 based on the amino acid profile and digestibility. It has a cap of 1.0, meaning that even if a protein exceeds requirements for every amino acid, it still maxes out at 1.0.

DIAAS (Digestible Indispensable Amino Acid Score) was recommended by the FAO in 2013 as a replacement. It measures digestibility at the end of the small intestine (ileal digestibility) rather than over the whole tract, and it has no cap, so high-quality proteins can score above 100.

Protein Source	PDCAAS Score	DIAAS Score	Notes
Whole egg	1.00	113	Excellent amino acid profile and digestibility
Whey protein	1.00	109	Fast-digesting, high leucine
Chicken breast	1.00	108	Complete protein, very lean
Whole milk	1.00	114	Mix of whey and casein
Soy protein isolate	1.00	90	Best plant source, complete amino acid profile
Pea protein	0.89	82	Good plant option, slightly low in methionine
Cooked kidney beans	0.68	59	Incomplete on their own, pair with grains
Wheat gluten	0.25	40	Low in lysine, poor protein source alone

The practical takeaway: if you eat animal protein, quality is rarely a concern. If you eat plant-based, combining different protein sources (grains + legumes, for example) fills in the gaps. The total amount matters more than the score of any single food, as long as you eat varied sources across the day.

Fibre: The Forgotten Macro

Fibre is technically a carbohydrate, but it behaves differently. Most fibre passes through the digestive system undigested, meaning it contributes minimal calories (about 2 cal/g on average, versus 4 for other carbs). But its health effects are significant. The NHS recommends 30g of fibre per day for adults. The American Heart Association suggests 25-30g. Most people in the UK get about 18g per day, and Americans average around 15g.

Fibre matters for macro tracking because it affects satiety (how full you feel), blood sugar response (fibre slows glucose absorption), and gut health (it feeds beneficial bacteria in the colon). High-fibre foods include vegetables, fruit, whole grains, legumes, nuts, and seeds. When planning your carbohydrate macro, prioritising fibre-rich carb sources over refined ones makes a meaningful difference to how satisfied you feel on the same calorie intake.

Food	Portion	Fibre (g)	Notes
Lentils (cooked)	1 cup / 200g	15.6	Also 18g protein - excellent dual-purpose food
Chia seeds	2 tablespoons / 28g	10.0	High in omega-3 as well
Avocado	1 medium	10.0	Mostly soluble fibre
Oats (dry)	1/2 cup / 40g	4.0	Beta-glucan fibre, good for cholesterol
Broccoli (cooked)	1 cup / 155g	5.1	Also high in vitamins C and K
Almonds	30g (about 23 nuts)	3.5	Also 6g protein

Alcohol: The Unofficial 4th Macro

Alcohol provides 7 calories per gram, sitting between carbs (4 cal/g) and fat (9 cal/g). It is sometimes called the fourth macronutrient because it contributes significant calories but is not classified alongside protein, carbs, and fat since it serves no nutritional function.

When you drink alcohol, your body treats it as a priority fuel source. The liver metabolises alcohol first, which means fat burning is essentially paused until the alcohol is cleared. A 2003 study by Siler et al. published in the American Journal of Clinical Nutrition found that whole-body fat oxidation decreased by 73% for several hours after alcohol consumption. This does not mean alcohol itself is stored as fat (very little of it is converted directly), but it delays the burning of everything else you eat alongside it.

For macro tracking purposes, the simplest approach is to count alcohol calories against either your carb or fat budget. A standard drink (a 175ml glass of wine, a pint of beer, or a single measure of spirits) contains roughly 100-180 calories. If you drink regularly, factoring these calories into your daily plan prevents unexplained stalls in progress. The Calorie Calculator can help you see how much room alcohol leaves in your daily budget.

Vegetarian and Vegan Macro Planning

Hitting protein targets on a plant-based diet is entirely possible, but it requires more planning than an omnivorous diet. The main challenge is that most plant proteins are incomplete, meaning they are low in one or more essential amino acids. The solution is combining complementary sources across the day. You do not need to combine them in the same meal (that is an outdated myth), but you do need variety over the course of each day.

Combination	Example Meal	Why It Works
Legumes + Grains	Rice and beans, lentil daal with naan, hummus with pitta	Legumes are low in methionine, grains are low in lysine - together they cover all essential amino acids
Legumes + Seeds	Chickpea salad with tahini, black bean tacos with pumpkin seeds	Seeds provide methionine that legumes lack
Soy (complete on its own)	Tofu stir-fry, tempeh sandwich, edamame snack, soy milk	Soy is one of the few plant proteins with a complete amino acid profile
Grains + Nuts	Peanut butter on toast, almond granola with oats	Complementary amino acid profiles

High-protein plant foods include tofu (10g per 100g), tempeh (19g per 100g), lentils (9g per 100g cooked), chickpeas (9g per 100g cooked), black beans (8g per 100g cooked), seitan (25g per 100g), and pea protein powder (around 24g per scoop). For more precise protein targets based on your body weight and training goals, the Protein Calculator provides tailored recommendations.

For understanding your total calorie needs before splitting into macros, the TDEE Calculator gives a detailed breakdown. For estimating body composition, the Body Fat Calculator uses the US Navy method. And if you want to plan a calorie deficit alongside your macro targets, the Calorie Deficit Calculator projects your timeline week by week.

All calculations run entirely in your browser. No personal data is sent to any server.

Sources

• Mifflin-St Jeor - A new predictive equation for resting energy expenditure (Am J Clin Nutr, 1990)
• ISSN Position Stand: Protein and Exercise (2017)
• NHS - How to get more fibre into your diet
• FAO - Dietary protein quality evaluation in human nutrition (DIAAS report, 2013)
• WHO/FAO/UNU - Protein and amino acid requirements in human nutrition (2007)
• Siler et al. - The inhibition of gluconeogenesis following alcohol (Am J Clin Nutr)
• American Heart Association - Dietary Fats and Fibre Guidelines