Calculate feed conversion ratio (FCR) from feed and live-weight gain, egg mass or milk mass. Enter a matched benchmark if available, or plan feed needs and output from your own expected FCR.
Feed Conversion Ratio Formula
The core formula divides how much feed an animal ate by how much product it produced over the same period:
FCR = Total Feed Consumed / Total Output Mass
The calculator also runs two planning formulas. To find how much feed you need for a target amount of gain:
Feed Needed = Target Output Mass * Expected FCR
To find how much gain a fixed amount of feed should produce:
Expected Output Mass = Feed Available / Expected FCR
Two secondary outputs come from the same numbers. Feed efficiency is the inverse of FCR, and feed cost per unit of gain scales FCR by the price of feed:
Feed Efficiency (%) = 100 / FCR Feed Cost per Unit Gain = FCR * Feed Price per Unit
- Total Feed Consumed: the weight of all feed the animal or group ate during the period. Use feed actually eaten, not feed delivered, so wastage does not inflate the result.
- Total Output: for live-weight gain, use final minus starting weight for the same group and period. Enter an animal count only when both weights are per animal; blank uses group totals. For egg or milk production, enter the mass produced.
- Expected FCR: the ratio you enter for planning, matching your feed basis and output measure. Species presets are not assumed.
- Feed Efficiency: how much gain you get from one unit of feed, shown as a percentage. Higher is better, the opposite direction from FCR.
- Feed Price per Unit: the cost of one unit of feed in the same weight unit you selected. It converts a ratio into a per-unit and total cost.
Feed and weight must be in the same unit before you divide, because FCR is a pure ratio with no unit of its own. The calculator keeps both on the unit you pick so an FCR of 1.8 means 1.8 kg of feed per 1 kg of gain, or 1.8 lb per 1 lb, either way.
Selecting a Matched Benchmark and Reading Feed Efficiency
Benchmarks must match feed basis, species, life stage, production system and output measure. The calculator compares your entered bounds without diagnosing health or management. Generic species ranges are not automatic grades. Milk/feed here is a simple mass ratio, not energy-corrected dairy feed efficiency.
| Animal | Benchmark basis | Notes |
| Broiler chicken | Use a matched source | Match age and feed basis |
| Layer hen (egg mass) | Use a matched source | Feed per unit of egg mass |
| Pig / swine | Use a matched source | Worsens with age |
| Sheep / goat | Use a matched source | Varies with breed and feed |
| Beef cattle | Use a matched source | Match growth stage and diet |
| Salmon (farmed) | Use a matched source | Match feed basis and system |
| Tilapia | Use a matched source | Warm-water species |
| Catfish | Use a matched source | Depends on system |
The second table converts any FCR into feed efficiency and into how much feed each 100 units of gain requires. It gives you a quick way to read the same result in three ways and to see how much feed you save as FCR drops.
| FCR | Feed efficiency | Feed per 100 units of gain |
| 1.3 | 76.9% | 130 units |
| 1.6 | 62.5% | 160 units |
| 1.8 | 55.6% | 180 units |
| 2.5 | 40.0% | 250 units |
| 4.0 | 25.0% | 400 units |
| 8.0 | 12.5% | 800 units |
The money angle follows directly. Because feed cost per unit of gain equals FCR times feed price, every 0.1 drop in FCR saves the price of 0.1 unit of feed for every unit of product you sell. At a feed price of 0.40 per kg, improving a broiler flock from 1.8 to 1.6 cuts feed cost from 0.72 to 0.64 per kg of live-weight gain, which is 80 saved for every 1,000 kg produced.
Example Problems
Example 1: FCR for a broiler flock. A group of 1,000 broilers ate 5,250 kg of feed total. They started at 0.04 kg each and finished at 2.2 kg each. Total gain is (2.2 – 0.04) times 1,000, which is 2,160 kg. FCR is 5,250 divided by 2,160, which is 2.43. Compare the 2.43056 FCR with a benchmark for the same age, feed basis and production system; this calculation alone does not diagnose flock performance.
Example 2: Feed needed for a target. You want to grow 1,000 kg of pig weight and assume an FCR of 3.0. Feed needed is 1,000 times 3.0, which is 3,000 kg. If feed costs 0.35 per kg, the feed bill for that gain is 3,000 times 0.35, which is 1,050.
Frequently Asked Questions
What is a good feed conversion ratio? A useful comparison matches species, growth stage, feed moisture basis, output definition and production system. Supply a justified range in the optional fields. Lower feed/output FCR means less feed per output under comparable conditions; a low ratio alone does not establish animal health or appropriate feeding.
Should I use feed delivered or feed eaten? Use feed actually eaten. If you count feed that was spilled, spoiled, or left in the feeder, your FCR looks worse than the animal’s true performance. Weighing leftover feed and subtracting it gives a far more accurate ratio, which is why feeder design and storage matter to the number.
How is FCR different from feed efficiency? They are inverses of the same relationship. FCR tells you how much feed produces one unit of gain, so lower is better. Feed efficiency tells you how much gain comes from one unit of feed, shown as a percentage, so higher is better. An FCR of 2.0 is the same as 50 percent feed efficiency. The calculator shows both so you can read the result whichever way your operation prefers.
