BSFL Yield & Bioconversion Calculator
Turn an organic waste stream into projected larval biomass, protein, lipids and frass — with the efficiency metrics, a live mass-balance flow, and a revenue estimate you can price yourself.
Advanced — efficiency within the substrate band
Slides the bioconversion rate, FCR and yields between the low and high ends of the published range for this substrate — poor conditions and high fibre sit low; controlled climate and balanced feed sit high.
How the BSFL yield calculator works
Black soldier fly larvae (Hermetia illucens) are among the most efficient bioconverters on the planet: they eat almost any organic waste and turn a large fraction of it into protein- and fat-rich body mass in under three weeks. This calculator models that transformation as a mass balance. Waste goes in; some is respired away as carbon dioxide and water vapour, some becomes larval biomass you can harvest, and the rest is left as frass, a nutrient-rich residue. Get the substrate and conditions right and the split tips toward biomass; get them wrong and most of the mass simply evaporates or rots.
The tool runs in three directions to match how people actually work. Waste → Biomass starts from a waste stream and projects the harvest, the metrics and the revenue. Target → Input reverses that: name a production quota and it tells you the daily waste and breeding you need. Colony Sizing begins from egg or neonate mass and applies stage-by-stage survival to size the rear-out and the feed. Every projection is driven by the specific substrate you pick, because that choice changes everything downstream.
Decoding the bioconversion efficiency metrics
Four numbers describe how well a colony is turning waste into value, and the calculator reports each one. They come straight from the bioconversion literature.
Waste reduction (WR) and the waste reduction index (WRI)
Waste reduction is the share of the starting substrate the larvae consume, and the index normalises it over time so you can compare fast and slow runs:
WR (%) = (Wₓ − Wₔ) ÷ Wₓ × 100 · WRI = WR ÷ t
where Wₓ is the initial substrate mass, Wₔ is the final residual, and t is the bioconversion time in days. A higher WRI means the colony is clearing waste faster — the metric that matters most to a waste manager whose goal is disposal.
Feed conversion ratio (FCR)
FCR is the single most important commercial number, because it sets how much feed each kilo of larvae costs:
FCR = (substrate added − residual substrate) ÷ final biomass
A lower FCR is better. Highly digestible food waste reaches an efficient 1.1 to 1.7; moderate streams sit near 3.6; fibrous substrates like straw and pure manure run higher still, because cellulose and lignin resist digestion.
Bioconversion rate (BCR) and conversion efficiency (ECD)
BCR is the headline yield — the percentage of starting waste that ends up as harvestable larvae — and typically peaks between 15% and 25% on good substrates. ECD, the efficiency of conversion of digested feed, goes deeper: it measures how well the larvae turn what they actually assimilate into body tissue, discounting the mass lost to CO₂, water and metabolic heat. Studies find 50–60% of the substrate's carbon is shunted into biomass, the rest respired away.
| Substrate | BCR | FCR | Protein (DM) | Lipid (DM) | Optimal moisture |
|---|---|---|---|---|---|
| Fruit & veg waste | 13.0–17.2% | 1.5–3.3 | 38–41% | 26–45% | 62–78% |
| Brewery spent grain | 14.5–23.3% | 1.2–2.5 | 43–45% | 36–38% | 55–65% |
| Poultry manure | 6.3–15.2% | 2.8–5.1 | 42–52% | 12–19% | 25–60% |
| Fish processing waste | 9.4–13.8% | 3.2–4.5 | ~53% | ~30% | 65–75% |
| Mixed organic waste | 18.4–28.8% | 1.1–2.5 | 44–46% | 32–35% | 42–70% |
Moisture, C:N ratio and co-digestion
Beyond the substrate label, three physiochemical levers decide performance. Moisture should sit between 60% and 80%; wetter than about 95% and the bed goes anaerobic and drowns the larvae, drier than 40% and they can barely feed, so very wet streams need dewatering or a dry bulking agent. The carbon-to-nitrogen ratio ideally lands between 16:1 and 30:1, with 16:1 to 18:1 best for protein and lipid yield; a high-carbon feed such as straw slows development and should be co-digested with a nitrogen-rich stream like fish or slaughterhouse waste to pull the ratio down. And pH works best between 6 and 8, though the larvae can partly self-regulate their bed. Mixing complementary streams — the practice called co-digestion — reliably beats any single waste, because it balances nutrients, steadies moisture and pH, and suppresses ammonia build-up.
Turning biomass into products and revenue
Harvested larvae are mostly water. Drying removes roughly 70% of the fresh weight, so dried larvae are about 30% of the fresh mass. That dry matter is then split by mechanical pressing into protein meal and lipid oil, commonly a 60/40 to 55/45 split, though a carbohydrate-rich diet like fruit waste pushes the oil fraction higher — BSF oil is dominated by lauric acid, up to 45–76% of the lipid on such diets. Defatted protein meal is the main revenue driver, competing with fishmeal at over $1,400 per tonne. Lipid oil serves oleochemicals and feed, and the leftover frass sells as an organic fertiliser with an N-P-K around 5-7-4. The calculator multiplies your projected outputs by market prices you can edit to reflect your region, giving a gross revenue figure — a planning illustration, not a promise.
Scope, methodology and a financial note. This tool applies published bioconversion ranges, stage survival rates and standard constants (45,000 neonates ≈ 1 g, 5DOL ≈ 2.5 mg, dried larvae ≈ 30% of fresh) transparently, so the numbers are well-founded planning estimates — not guarantees. Real yields shift with genetics, climate control, feed quality and processing losses. The revenue figure is an illustration for planning only and is not financial or investment advice; verify prices and costs for your own operation.
FAQ
How do you calculate BSFL feed conversion ratio (FCR)?
FCR = (substrate added − residual substrate) ÷ final biomass. A lower number is more efficient. Food waste can reach 1.1–1.7; fibrous manures and straw run 2.8–5 or higher. The calculator uses substrate-specific FCR ranges so the estimate matches your feedstock.
What is the bioconversion rate of black soldier fly larvae?
BCR = final larval biomass ÷ substrate added × 100. On balanced substrates it usually falls between 15% and 25%, highest for mixed organic waste and lowest for pure manures. The tool applies a range per substrate, not one flat figure.
What is the optimal C:N ratio for black soldier fly larvae?
Around 16:1 to 30:1, with 16:1–18:1 best for protein and lipid yield. High-carbon feeds like straw should be co-digested with a nitrogen-rich stream such as fish waste to lower the ratio. Larvae also prefer pH 6–8, which they can partly self-regulate.
How much protein and oil do you get from BSFL?
Dried larvae are about 30% of the fresh weight. That dry matter splits into protein meal and lipid oil, commonly 60/40 to 55/45. Carbohydrate-rich diets like fruit waste raise the lipid fraction, which is dominated by lauric acid.
How much substrate does it take to rear BSFL to harvest?
Multiply the target fresh biomass by the substrate's FCR. In Colony Sizing mode the calculator starts from your egg or neonate mass, applies about 80% egg-to-neonate, 90% nursing and 95% bioconversion survival, and sizes both the harvest and the feed needed.
Is black soldier fly farming profitable?
It depends on protein meal (competing with fishmeal above $1,400/tonne), lipid oil, and frass fertiliser, set against capital, labour, energy and processing costs. The calculator estimates gross revenue from your outputs and editable prices, but it is a planning illustration, not investment advice.