Feed Conversion Ratio Calculator (FCR)
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/9/2026
The feed conversion ratio (FCR) is calculated with feed consumed ÷ weight gain. For 50 kg of feed consumed and 20 kg of weight gain, the FCR is 2.5: it takes 2.5 kg of feed to produce 1 kg of growth.
Explanation
The feed conversion ratio, or FCR, is one of the most widely used performance indicators in livestock farming: it measures how many kilograms of feed are needed to produce one kilogram of live weight gain. The lower the FCR, the more efficiently the animal (or group of animals) converts its feed into growth — an FCR of 1.5 is therefore more efficient than an FCR of 3. This indicator varies enormously by species and farming method: broiler chickens typically show the lowest FCRs (often around 1.5 to 1.8), followed by pigs (around 2.5 to 3), while beef cattle, whose metabolism is very different, generally sit well above (often 6 to 8 or more). Comparing the FCR of one farm to another therefore only makes sense between animals of the same species, under comparable farming conditions (age, feed, genetics, climate): an isolated FCR, without this context, doesn't say much. This calculator gives the raw feed conversion ratio over the chosen period; for a reading of a population's overall growth rather than a feed efficiency metric, see our population growth rate calculator; the energy an animal burns just to sustain itself, separate from what its feed converts into growth, is what our animal basal metabolic rate calculator estimates.
Example: 50 kg of feed consumed, 20 kg of weight gain
Inputs
Feed consumed: 50 kg. Weight gain: 20 kg.
Calculation
FCR = 50 ÷ 20 = 2.5.
Result
It took 2.5 kg of feed to produce each kilogram of weight gain over this period.
Frequently asked questions
Is a lower FCR always preferable?
Generally yes for the economic and environmental efficiency of the farm (less feed consumed for the same weight gain), but FCR alone isn't enough to judge a farm's overall quality: it must be weighed against animal health, welfare, final product quality, and farming conditions. An artificially low FCR achieved at the expense of animal health isn't a desirable goal.
Over what period should FCR be measured?
FCR can be calculated over a complete fattening cycle or over a shorter period (a week, a month). The choice of period depends on the goal: an overall FCR across the whole cycle gives a general picture, while periodic tracking allows an earlier detection of a performance drop (illness, feed quality issue).
Can FCR be compared between two different species?
No, that isn't meaningful: FCR strongly depends on each species' own metabolism (ruminants like cattle have a very different metabolism from poultry or pigs) as well as the farming method. The comparison only makes sense between animals of the same species, under similar conditions.