How the Protein Powder Calculator Works
This calculator combines two tools most competitors keep separate: a personalised protein target (based on your weight, goal, and activity level) and a scoop calculator that tells you exactly how many scoops per day you need — after subtracting what you already get from food. Add your tub size and price to unlock cost-per-gram analysis.
Daily Protein Targets by Goal
| Goal | g/kg bodyweight | 80 kg example | Source |
|---|---|---|---|
| Maintain | 1.0–1.2 g/kg | 80–96 g | WHO RDA + sedentary buffer |
| Build muscle | 1.6–2.0 g/kg | 128–160 g | Morton et al. 2018 meta-analysis |
| Lose fat | 1.8–2.2 g/kg | 144–176 g | Helms et al. 2014 |
| Athlete | 2.0–2.4 g/kg | 160–192 g | ISSN position stand 2017 |
Protein Powder Types Compared
| Type | Protein/scoop | Speed | Best for |
|---|---|---|---|
| Whey concentrate | 20–22 g | Fast | Post-workout, general use |
| Whey isolate | 24–26 g | Fast | Lactose intolerant, lean bulk |
| Casein | 24 g | Slow (6–8h) | Pre-sleep, hunger control |
| Pea protein | 20–22 g | Moderate | Vegan, complete profile |
| Rice protein | 20–22 g | Moderate | Vegan, combine with pea |
| Soy isolate | 22–24 g | Moderate | Best single-source plant option |
How to Calculate Cost Per Gram of Protein
The only fair way to compare protein powder value is cost per gram of protein — not cost per kg of powder, since protein density varies widely between products.
Total protein in tub = (tub weight ÷ scoop size) × protein per scoop
Cost per g protein = tub price ÷ total protein in tub
Example: $40 tub / 1kg / 25g protein per 34g scoop
→ 29 scoops × 25g = 735g protein → $0.054/g → $5.44 per 100g
Frequently Asked Questions
How much protein powder do I need per day?
It depends on your total daily protein target and how much protein you already get from food. Enter your weight, goal, and activity level to get your target, then add your scoop size and protein per scoop — the calculator shows exactly how many scoops cover the gap from food alone.
How much protein do I need per day?
For muscle building, the evidence supports 1.6–2.2 g/kg bodyweight per day. Maintaining muscle requires 1.0–1.2 g/kg. Fat loss with muscle preservation requires 1.8–2.2 g/kg — higher than muscle building because of the caloric deficit. Athletes in hard training benefit from the upper end of 2.0–2.4 g/kg.
How many scoops of protein powder per day?
Most people need 1–3 scoops per day depending on their protein target and food intake. If you eat a high-protein diet (meat, fish, dairy, eggs at most meals) you may only need 1 scoop to close the gap. If you eat minimal animal protein, 2–3 scoops may be needed to hit muscle-building targets.
How do I calculate the best value protein powder?
Compare cost per 100g of protein — not cost per kg of powder. A 1kg tub at £20 with 20g protein per 30g scoop delivers 667g of protein, costing £3.00 per 100g. A 2kg tub at £50 with 25g protein per 35g scoop delivers 1,428g of protein, costing £3.50 per 100g. The cheaper tub wins on cost per gram.
Is protein powder necessary to build muscle?
No. Protein powder is a supplement — a convenient way to close gaps in dietary protein, not a requirement. Athletes who consistently hit their protein target from whole foods (chicken, fish, beef, eggs, dairy, legumes) build muscle at the same rate as those using supplements when total intake is matched.
What is the best time to take protein powder?
Total daily protein intake matters far more than timing. However, distributing protein across 3–5 meals of 25–40g each maximises muscle protein synthesis throughout the day. Post-workout is convenient but not uniquely superior. Pre-sleep casein protein has modest evidence for overnight muscle protein synthesis.
What is the difference between whey concentrate and whey isolate?
Whey concentrate contains 70–80% protein by weight with small amounts of fat and lactose. Whey isolate is further filtered to 90%+ protein with minimal fat and lactose — better for lactose-sensitive individuals and slightly higher protein per scoop. Isolate costs more; concentrate is better value for most people.
Can I take too much protein powder?
High protein intake (up to 3.5 g/kg) is safe for healthy adults with normal kidney function. The main concern is caloric displacement — protein powder calories still count toward daily total. Exceeding your target by 500+ kcal/day from supplements can cause unintended fat gain.
Does protein powder expire?
Yes. Most protein powders have a 1–2 year shelf life. Degradation is gradual — expired powder loses some amino acid content and may taste off, but is generally not harmful. Store in a cool, dry place away from moisture to maximise shelf life. The days-supply calculation in this tool helps you avoid buying more than you can use.
Is plant protein powder as effective as whey?
For muscle building, plant protein (pea, rice, soy) is comparably effective to whey when consumed in equal amounts and with a complete amino acid profile. Pea + rice combined provides all essential amino acids. Soy protein isolate is the most complete single-source plant protein. Leucine content per serving is slightly lower in most plant powders, so slightly higher doses may be needed.