Tools
Whey protein leucine calculator
Leucine is the amino acid that flips the muscle-protein-synthesis switch. The target per serve is 2.5g for adults and 3g for over-65s. This calculator estimates how much leucine you’re getting from a whey serve and shows whether it clears the threshold.
3.0g leucine per serve (estimated)
- Hits the 2.5g MPS threshold for adults in 1 serve.
- Clears the 3.0g older-adult / leucine-trigger threshold in 1 serve.
Estimates only. Actual leucine content depends on protein source and processing — typical ranges: WPI ~12% of protein, WPC ~10%, hydrolysed ~13%. For age 65+, prioritise the 3g target per meal to overcome anabolic resistance (Schoenfeld & Aragon, 2018).
How leucine fractions work
- WPI: ~12% of protein is leucine
- Hydrolysed: ~13% (slight bump from processing)
- WPC: ~10% (residual fat/lactose dilutes it)
- Blend: ~10% (conservative midpoint)
Estimates only — actual values depend on the source dairy and processing method. For lab-tested numbers, check the brand’s spec sheet.
Leaderboard
Cheapest whey hitting the 2.5g leucine threshold
Live across 10 products from our daily price scrape — every one delivers ≥2.5g of estimated leucine in a single serve and ranks by $/kg of actual protein.
FAQ
Leucine + whey protein, answered.
What is the leucine threshold and why does it matter?
Leucine is the branched-chain amino acid that flips the muscle protein synthesis (MPS) switch. Research (Schoenfeld & Aragon 2018, Layman et al. 2019) shows you need roughly 2.5–3g of leucine per meal/serving to maximise the MPS response. Below the threshold, additional protein adds amino acids but doesn’t fully trigger the anabolic signal.
How do you estimate leucine content from protein subtype?
We use established industry ratios: whey isolate (WPI) is ~12% leucine by weight of protein, hydrolysed whey ~13%, whey concentrate (WPC) ~10%, and whey blends ~10%. So a 25g serve of WPI delivers ~3g leucine, while a 25g serve of WPC delivers ~2.5g.
Should older adults aim for the 3g target instead of 2.5g?
Yes — anabolic resistance increases with age, so adults over ~65 typically need a higher per-meal leucine dose to trigger the same MPS response. The 3g threshold is the conservative recommendation for older trainees.
What's the cheapest whey protein that hits the leucine threshold in Australia?
Today the cheapest whey hitting the 2.5g leucine threshold in one serve is Blackbelt Platinum Protein at $45.91/kg of protein, with an estimated 3.0g leucine per serve.
Is leucine the only thing that matters in a whey protein?
No — total protein per serve, total daily protein, digestibility, and overall amino acid profile all matter. Leucine is the trigger; you still need a complete amino acid pool. Whey from any source provides this; the leucine threshold is a useful "is this serve big enough" gut-check.