Protein Calculator

About Protein Calculator

How Much Protein Do I Need?

The RDA of 0.8 g per kg of body weight is the minimum to prevent deficiency in sedentary adults - not the optimal amount for active people or anyone trying to change their body composition. Evidence-based recommendations are higher:

Activity Level / Goal	g per kg body weight	g per lb body weight	Example (75 kg / 165 lb)
Sedentary adult (RDA minimum)	0.8	0.36	60g
Recreational exerciser	1.0 - 1.2	0.45 - 0.55	75 - 90g
Endurance athlete	1.2 - 1.4	0.55 - 0.65	90 - 105g
Strength training / muscle gain	1.6 - 2.2	0.7 - 1.0	120 - 165g
Fat loss (preserving muscle)	1.8 - 2.4	0.8 - 1.1	135 - 180g
Older adults (60+)	1.0 - 1.2	0.45 - 0.55	75 - 90g

Research consistently shows that active adults benefit from 1.6-2.2 g/kg, with the higher end particularly important during fat loss (to preserve muscle) and during heavy resistance training (to support muscle growth). The International Society of Sports Nutrition (ISSN) position stand supports this range.

Why Is Protein Higher During Fat Loss?

When you eat in a calorie deficit, your body draws energy from both fat stores and muscle tissue. Higher protein intake signals the body to preserve muscle. Studies show that increasing protein from 1.2 to 2.0+ g/kg during a deficit significantly reduces muscle loss while maintaining the same rate of fat loss. This is why the fat loss recommendation (1.8-2.4 g/kg) is actually higher than the muscle gain recommendation.

Per-Meal Protein Distribution

Research on muscle protein synthesis (MPS) suggests that spreading protein across meals is more effective than eating most of it in one sitting. Each meal triggers a spike in MPS that lasts about 3-5 hours before returning to baseline.

Meals per Day	Protein per Meal (target 150g/day)	Notes
3 meals	50g each	Simple, practical for most schedules
4 meals	37-38g each	Better MPS distribution
5 meals	30g each	Frequent stimulation, harder to schedule

The practical sweet spot for most people is 3-4 protein-containing meals per day, with 25-50g of protein each. Going above 40-50g per meal still provides calories and amino acids, but the MPS benefit plateaus.

Protein Content of Common Foods

Food	Serving	Protein (g)	Calories
Chicken breast (cooked)	150g / 5.3 oz	46	231
Salmon fillet (cooked)	150g / 5.3 oz	34	309
Lean beef mince (cooked)	150g / 5.3 oz	38	321
Eggs	2 large	12	144
Greek yoghurt (0% fat)	200g / 7 oz	20	118
Cottage cheese	200g / 7 oz	22	164
Whey protein powder	1 scoop (30g)	24	120
Tofu (firm)	150g / 5.3 oz	18	174
Lentils (cooked)	200g / 7 oz	18	232
Chickpeas (cooked)	200g / 7 oz	15	328
Peanut butter	2 tbsp (32g)	7	188
Milk (semi-skimmed)	250ml	9	125

Plant-Based Protein

Plant proteins can fully meet daily targets, but there are some differences to consider:

Factor	Animal Protein	Plant Protein
Complete amino acid profile	Yes (all sources)	Some (soy, quinoa), most need combining
Digestibility (DIAAS score)	Higher (90-100%)	Lower (60-85% for most)
Leucine content	Higher per gram	Lower per gram
Practical recommendation	Use standard targets	Increase target by 10-20% to compensate

If you eat exclusively plant-based, aiming for the higher end of the protein range (and combining complementary sources like rice + beans, or using soy and pea protein) ensures adequate essential amino acids. The leucine content of plant sources is lower, so slightly higher total protein compensates.

Protein Timing

Timing	Evidence	Practical Advice
Post-workout (within 2 hours)	Moderate support - MPS is elevated after training	20-40g protein after training is a good habit
Before bed	Some evidence - casein before sleep supports overnight MPS	30-40g of slow protein (casein, cottage cheese) if convenient
Morning / breakfast	Practical benefit - many people under-eat protein at breakfast	Including protein at breakfast helps hit daily totals
The "anabolic window"	Overstated - total daily intake matters more than exact timing	Do not stress about eating within 30 minutes of training

Is Too Much Protein Harmful?

For healthy adults with normal kidney function, protein intakes up to 2.2 g/kg (and even higher in short-term studies up to 3.3 g/kg) have not shown kidney damage or other adverse effects. The concern about high protein harming kidneys comes from studies on people with pre-existing kidney disease, where protein restriction is medically appropriate. If you have kidney disease, consult your doctor about protein intake.

Protein Quality: PDCAAS vs DIAAS Scoring

Not all protein sources are equal. Two scoring systems measure how well your body can use the protein in a given food:

PDCAAS (Protein Digestibility-Corrected Amino Acid Score) was the standard from 1991. It caps scores at 1.0, meaning any protein that meets minimum requirements for all essential amino acids gets the same top score. This hides real differences between foods.

DIAAS (Digestible Indispensable Amino Acid Score) replaced PDCAAS in 2013 per FAO recommendation. It measures individual amino acid digestibility at the ileum (end of the small intestine) and does not cap at 100%, so higher-quality proteins can score above 100.

Food	PDCAAS	DIAAS	Limiting Amino Acid
Whole milk	1.00	1.14	None
Eggs	1.00	1.13	None
Chicken breast	1.00	1.08	None
Whey protein isolate	1.00	1.09	None
Soy protein isolate	1.00	0.90	Methionine
Pea protein	0.89	0.82	Methionine
Kidney beans	0.68	0.59	Methionine
Rice protein	0.50	0.42	Lysine
Wheat gluten	0.25	0.21	Lysine

Practical takeaway: if you rely on plant protein, combining sources that complement each other's limiting amino acid makes a big difference. Rice protein is low in lysine; pea protein is low in methionine. Mixed together, they cover each other's gaps and score much closer to animal sources. This is why most commercial vegan protein powders use a rice-pea blend. Traditional food pairings figured this out centuries ago without any scoring system: beans and rice in Latin America, lentils and flatbread in South Asia, and hummus with pitta bread in the Middle East all combine complementary amino acid profiles.

Whey vs Casein vs Plant Protein

If you use protein supplements, the type you pick affects absorption speed and how well it supports muscle protein synthesis:

Type	Absorption Rate	Leucine per 25g Serving	Best Time to Use	Notes
Whey isolate	Fast (peaks at 60-90 min)	~2.7g	Post-workout	Highest leucine, fastest MPS trigger
Whey concentrate	Fast (peaks at 60-90 min)	~2.3g	Any time	Cheaper, slightly more fat/lactose
Casein (micellar)	Slow (sustained over 5-7 hours)	~2.0g	Before bed	Slow-release, good overnight MPS
Pea protein	Medium	~1.7g	Any time	Best single plant source for leucine
Rice-pea blend	Medium	~2.0g (varies)	Any time	Complete amino profile when combined
Soy isolate	Medium-fast	~1.8g	Any time	Complete protein, mild taste

Leucine is the amino acid that triggers muscle protein synthesis. The "leucine threshold" for maximal MPS stimulation is roughly 2.5g per meal. Whey hits this in a single 25g scoop. Plant proteins typically need 35-40g per serving to reach the same leucine level. This does not mean plant protein is bad; it just means you need slightly more of it per sitting.

Protein for Aging Adults and Sarcopenia Prevention

Sarcopenia is the progressive loss of muscle mass and strength that begins around age 30 and accelerates after 60. Adults lose roughly 3-8% of muscle mass per decade after 30 without intervention. The ESPEN (European Society for Clinical Nutrition and Metabolism) guidelines recommend that older adults consume 1.0-1.2 g/kg/day as a baseline, and 1.2-1.5 g/kg/day if they have an acute or chronic illness.

The challenge is that older adults are less responsive to protein. A phenomenon called "anabolic resistance" means they need more protein per meal to trigger the same MPS response as a younger person. While a 25-year-old might maximise MPS with 20g of protein, someone over 65 may need 35-40g per meal for the same effect.

Practical recommendations for adults over 60:

• Aim for at least 1.2 g/kg body weight per day (a 70 kg person needs at least 84g)
• Include 30-40g of high-quality protein at each meal, not just dinner
• Prioritise leucine-rich sources (dairy, eggs, meat, or whey supplements)
• Combine with resistance exercise, which is the single most effective intervention against sarcopenia

Does High Protein Damage Your Kidneys?

This is one of the most persistent nutrition myths. The concern originated from observations that people with existing kidney disease benefit from protein restriction. That finding was then incorrectly generalised to healthy adults.

A 2018 meta-analysis published in The Journal of Nutrition by Devries et al. examined data from 28 trials and found no adverse effects of higher protein intake (up to 2.2 g/kg/day) on kidney function in healthy adults. Markers like glomerular filtration rate (GFR) and blood urea nitrogen showed normal adaptations, not damage. A separate 2016 study by Antonio et al. followed resistance-trained men eating 2.6-3.3 g/kg/day for a full year with no negative kidney effects.

The bottom line: if your kidneys are healthy, protein intakes in the 1.6-2.2 g/kg range are well supported by evidence and pose no known risk. If you have diagnosed kidney disease (especially stage 3 or higher CKD), work with a nephrologist to set an appropriate protein target. Staying well hydrated helps your kidneys process protein efficiently at any intake level, so use the Water Intake Calculator alongside your protein target to make sure you are covering both bases.

For a complete macronutrient split including carbs and fat alongside your protein target, use the Macro Calculator. To understand your total daily calorie needs, start with the TDEE Calculator. If you are tracking body composition alongside nutrition, the Body Fat Calculator estimates your fat and lean mass percentages.

All calculations run in your browser. No personal data is collected or stored.

Sources

• International Society of Sports Nutrition (ISSN) Position Stand: Protein and Exercise
• FAO - Dietary Protein Quality Evaluation in Human Nutrition (DIAAS)
• ESPEN Guideline on Clinical Nutrition in Geriatrics
• Devries et al. 2018 - Changes in Kidney Function on Higher Protein Diets (Journal of Nutrition)
• Antonio et al. 2016 - High Protein Intake and Kidney Function
• NHS - Meat and Protein in Your Diet