This feed conversion ratio calculator finds FCR — total feed consumed ÷ live weight gained — the efficiency number that decides profitability in livestock, poultry and aquaculture production. Lower is better: every decimal point is feed cost per kilogram of saleable growth.

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One Ratio Runs the Feed Bill

Feed is 60–80% of animal production cost, so the industry organizes itself around this quotient. The defaults model a pig grow-finish group: 2,450 kg of feed for 1,180 kg of live gain = FCR 2.08 — a good modern figure (its reciprocal, feed efficiency, is 48.2%: each kilogram of feed became 0.48 kg of pig). The species league table is physiology made visible: salmon convert at ~1.2 because they neither fight gravity nor burn feed on body heat; broilers reach 1.5–1.8 after a century of selection; cattle on grain sit at 5.5–6.5 because ruminant fermentation and a large maintenance overhead tax every kilogram. Comparing FCR across species is thus meaningless except as biology appreciation — comparisons live WITHIN species, system and diet energy density, where differences of 0.1 (a few cents per kilogram of gain, millions at scale) justify genetics programs, feed formulation changes and barn retrofits.

The definitional traps matter more than the arithmetic. FCR can be computed on live weight or carcass weight (carcass FCR runs higher — dressing percentage removes gut and bone), on feed delivered or feed consumed (wastage invisible in the first), and for survivors only or the whole placed group (mortality feed inflates the honest figure — “economic FCR”). Papers and feed-company brochures exploit the friendly variants; farm decisions need the strict one: all feed in, all live gain out, same animals, same period. Get those four boundaries right and the calculator’s division is the whole science; get them wrong and you’re benchmarking fiction.

One modern extension deserves note: precision feeding systems now compute FCR per pen per day from automated feed-intake and weighing data, catching conversion slippage (a disease brewing, a ration mixing error) within days instead of at closeout. The formula never changes — only the bookkeeping frequency does.

Worked Examples (Verified)

  • Defaults (pigs): 2,450 ÷ 1,180 = 2.08.
  • Broilers: 3,400 kg feed, 2,100 kg gain → 1.62.
  • Feedlot cattle: 7,800 kg feed, 1,300 kg gain → 6.00.

FCR Discipline

  • Same group, same period, both sides of the division — mixed boundaries are the #1 source of fantasy FCRs.
  • State the basis: live-weight FCR and carcass-weight FCR differ by the dressing percentage; never mix them in one comparison.
  • Mortality counts: feed consumed by animals that died stays in the numerator for economic FCR.
  • Diet energy density moves FCR mechanically: diluting energy with fiber raises FCR even with identical biology — compare diets on energy-corrected terms for R&D.
  • Age phase matters: young animals convert best; whole-life FCR is the weighted story of phase FCRs, and finisher phases dominate feed tonnage.

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Frequently Asked Questions

How is feed conversion ratio calculated?

FCR = total feed consumed ÷ total live weight gained over the same period for the same group of animals. Units cancel (kg/kg), so the same value works in pounds. Example: 2,450 kg of feed producing 1,180 kg of gain gives FCR 2.08 — meaning 2.08 kg of feed per kilogram of growth. Its reciprocal (gain ÷ feed) is feed efficiency, here 48.2%. Enter feed and gain above for both.

What is a good FCR for chickens, pigs, cattle and fish?

With modern genetics and good management: broiler chickens 1.4–1.8, farmed salmon 1.1–1.3, grow-finish pigs 2.3–2.8, grain-fed feedlot cattle 5.5–6.5, sheep higher and more variable. Backyard and heritage-breed systems run above these bands — that’s not failure, it’s different objectives. Judge an FCR within its species, diet and system; a 2.08 pig (our default example) is excellent while a 2.08 broiler would be a disaster.

Why do salmon convert feed so much better than cattle?

Three compounding physics: fish are ectotherms (no feed burned for body heat), near-neutrally buoyant (no skeleton-and-posture energy tax of standing), and fed extremely nutrient-dense diets. Cattle pay for a 39 °C body, a fermentation vat (the rumen loses energy as methane and heat of fermentation), and months of maintenance before finishing. FCR league tables are thermodynamics and anatomy, not a moral ranking of species or farmers.

FCR vs feed efficiency — which to use?

They’re reciprocals: efficiency = gain ÷ feed (higher better), FCR = feed ÷ gain (lower better). Poultry and fish industries conventionally quote FCR; dairy often quotes efficiency (milk per feed) or feed conversion efficiency. Convert freely (efficiency % = 100 ÷ FCR) — but quote one consistently within a report, because a “2.0” means excellent as FCR and impossible as efficiency ratio in most species.

Does FCR include the breeding herd’s feed?

Standard grow-out FCR does not — it covers the growing animals’ feed only. Whole-system accounting (sometimes “cradle FCR”) allocates breeder/sow feed across progeny and runs higher; pig full-cycle FCR including the sow herd is roughly 0.2–0.4 above grow-finish FCR. Know which boundary a published figure uses before comparing it with your farm’s number — vendors prefer the flattering one.

How can I improve my operation’s FCR?

The levers, in usual impact order: reduce feed waste (feeder adjustment alone can be worth 0.1–0.3), diet formulation to the animals’ exact phase requirements (excess protein is expensive urine), health (subclinical disease taxes conversion silently), environment (cold barns burn feed as heat — pigs below thermoneutral convert noticeably worse), and genetics. Measure first with this formula on honest boundaries; improvements claimed without the mortality-and-waste accounting rarely survive contact with the feed bill.

What is economic FCR / adjusted FCR?

Adjusted variants standardize comparisons: economic FCR charges all feed (including that eaten by mortalities) against surviving gain; other adjustments correct to a common slaughter weight or include mortality rate directly (some broiler standards fold mortality % in). Each adjustment answers a specific management question. The base formula here is the foundation — adjustments are bookkeeping layers on the same two numbers.

Is this feed conversion ratio calculator free?

Yes — free, instant, no sign-up. Enter total feed consumed and live weight gained for FCR and feed efficiency percentage.