Protein Calculator

The Recommended Dietary Allowance (RDA) of 0.8 grams per kilogram of body weight is the minimum amount needed to prevent deficiency in a sedentary person. Your personalized target reflects the optimal amount to support your specific goals, based on extensive research showing that higher intakes are more effective for improving body composition, strength, and recovery.

Protein needs are not one-size-fits-all. The JISSN paper shows that different goals require different protein intakes. For Build Muscle & Strength, a range of 1.4-2.0 g/kg is effective. However, for Lose Fat & Preserve Muscle, protein needs are at their highest—up to 2.3-3.1 g/kg of lean body mass—to protect muscle tissue in a calorie deficit. This calculator automatically adjusts these multipliers based on the goal you select to provide the most effective recommendation.

Protein recommendations are scaled to your body weight (in g/kg) because your body's protein needs are directly related to the amount of tissue you have to maintain, repair, and build. A larger individual has more muscle and organ tissue, requiring more protein for daily turnover than a smaller individual. This method makes your protein target a truly personalized metric, rather than a generic daily amount.

This is an advanced feature that makes our calculator more precise. When you are losing weight, your primary goal is to lose fat, not precious muscle. Since muscle is the tissue that requires protein for maintenance, the most accurate way to calculate your needs in a calorie deficit is to base it on your Lean Body Mass (muscle, bones, organs) rather than your total weight. This ensures you're consuming enough protein to protect your muscle while you lose fat, which is critical for maintaining metabolic health.

For individuals with healthy, functioning kidneys, the overwhelming body of scientific evidence shows no harmful effects from high protein consumption. The 2024 JISSN review states this clearly, referencing multiple long-term studies where even very high intakes showed no negative impact on markers of kidney function. The myth of protein-induced kidney damage originates from recommendations for patients with pre-existing kidney disease, and this advice does not apply to the healthy population.

Leucine is an essential amino acid that acts as the primary "on-switch" for Muscle Protein Synthesis (MPS)—the process of repairing and building muscle. To effectively flip this switch, a meal needs to contain a sufficient amount of leucine. The JISSN paper highlights that a meal containing 20-40 grams of high-quality protein generally provides enough leucine (around 2.5-3g) to cross this threshold and maximize the MPS response. Our "Meal-by-Meal Split" helps you plan meals that are potent enough to hit this trigger.

The concept of a 30-60 minute post-workout "anabolic window" has been largely overstated. The JISSN review concludes that total daily protein intake is the most critical factor for recovery and muscle growth. While a protein-rich meal 1-2 hours after your workout is a great strategy, the window of opportunity is much larger than previously believed. The priority should always be hitting your daily target consistently.

As we age (especially after 60), our bodies develop a condition called "anabolic resistance," meaning we need more protein to trigger the same muscle-building response as a younger person. The JISSN paper supports this, recommending a higher baseline of 1.0-1.2 g/kg for general health in older adults. Our calculator automatically adjusts for this to help combat age-related muscle loss (sarcopenia) and maintain strength.

Absolutely. A well-planned vegan or vegetarian diet can certainly support muscle growth. To ensure you meet your needs, the scientific literature suggests consuming a ~20-40% higher total daily protein intake compared to an omnivorous diet to account for differences in amino acid profiles. Our calculator applies a 25% adjustment to help you achieve this. Prioritizing a variety of high-quality plant proteins is key.

Protein needs are significantly altered during pregnancy and lactation. This topic falls outside the scope of this specific tool and the JISSN paper, which focuses on sports nutrition for non-pregnant populations. We strongly advise consulting with your obstetrician or a registered dietitian who specializes in prenatal nutrition to determine a safe and effective protein target for you and your baby.

Our calculator is built on the foundation of the most current scientific literature: the 2024 position stand from the Journal of the International Society of Sports Nutrition (JISSN). Our methodology is transparent, evidence-based, and designed to provide you with a truly personalized protein target.

The Core Formula

The fundamental calculation is based on scaling protein intake to your body weight in kilograms (kg).

Protein Target (grams) = Base Weight (kg) × Goal-Specific Multiplier

Here is our step-by-step process:

Step 1: Establishing Your Base Weight

First, we establish a consistent unit of mass. If you enter your weight in pounds (lbs), it is converted to kilograms (kg) using the standard formula:

Weight (kg) = Weight (lbs) / 2.20462

Step 2: Selecting Your Goal-Specific Multiplier

Based on your chosen goal, we apply a specific multiplier drawn directly from the ranges identified as effective in the JISSN paper.

Step 3: Applying Advanced Adjustments

1. Age Modifier (Anabolic Resistance): For users 60 and older, the body requires more protein to trigger muscle growth. Our calculator automatically increases the minimum required protein intake by 20% to account for this.
2. Lean Body Mass (LBM) for Fat Loss: For the 'Lose Fat' goal, your protein needs are best tied to your muscle mass. We use the Body Fat % you provide (either via the visual guide or direct input) to calculate your LBM:

   LBM (kg) = Body Weight (kg) × (1 - (Body Fat % / 100))

   This LBM value is then used as the "Base Weight" for the fat loss calculation.
3. Dietary Preference: Plant-based proteins can have different amino acid profiles. To ensure you meet your needs, if you select Vegetarian or Vegan, we apply a +25% adjustment to your final protein target, in line with scientific recommendations.

Full Calculation Example

Let's walk through an example for a user named Sarah:

• Age: 40
• Weight: 150 lbs
• Goal: Build Muscle & Strength
• Diet: Omnivore

1. Convert Weight to KG:

   150 lbs / 2.20462 = 68.04 kg

2. Select Multiplier:
   • Sarah's goal uses the 1.4 - 2.0 g/kg range.
   • Base Range: (68.04 × 1.4) to (68.04 × 2.0) = 95g - 136g
3. Apply Adjustments:
   • Age: Sarah is under 60. No age adjustment is needed.
   • Diet: Sarah is an omnivore. No dietary adjustment is needed.
4. Final Recommendation:
   • Sarah's optimal range is 95g - 136g. Her primary Target is the midpoint of this range, which is 116g of protein per day.