Horse Feed Tag Mathematics

It takes some time and math skills to properly understand how the guaranteed analysis relates to what your horse is actually taking in every day!
It takes some time and math skills to properly understand how the guaranteed analysis relates to what your horse is actually taking in every day!

We often receive questions from horse owners, wondering what the various units of measure on horse feed tags mean, and how they can use those units to figure out what their horse is consuming…and wondering why in the world they have to be so confusing, too!

In short, feed companies use the units of measurements on nutrients that we do, because we are required to. Why? Because horse feeds and other livestock feeds are labeled as required by AAFCO (American Association of Feed Control Officials) and the various state Feed Control regulations.  These regulatory bodies establish the units which are to be used for each nutrient in tag guarantees.

To break it down, there are 4 common units used on feed tags.  To help you understand them all, here’s a quick overview of how they work, along with examples of how to do the appropriate math:

Protein, amino acids, fat, fiber and macro minerals (calcium, phosphorus, magnesium and potassium) are listed as a % minimum or maximum.

  • To calculate the amount supplied per pound, you can convert % to a decimal fraction by moving the decimal point 2 places to the left, then multiply by the pounds fed.
  • As a horse’s daily intake requirements are sometimes given in grams, we can convert those pounds of intake to grams as well.
    • For those of us that are mathematically challenged, a quick Google search of “pounds to grams” will provide a handy conversion calculator!


  • A feed that is 14% protein would contain 1 lb x 0.14 = 0.14 lb of protein in 1 pound of feed.
    • If you want to measure in ounces, there are 16 ounces per pound, so the same pound of feed would contain 0.14 x 16 = 2.24 ounces of protein.
    • If the requirements are given in grams, we know that there are 453.6 grams per pound, so the feed would contain 453.6 x 0.14 = 63.5 grams of protein per pound of feed.
  • Feeding 5 lbs of this feed per day, results in feeding 0.7 lbs, or 11.2 ounces, or 317.5 grams, of protein per day.

Trace minerals (copper, zinc, manganese and selenium) are expressed as “ppm” or parts per million.

  • One part per million is the same as one milligrams per kilogram.
  • 1 kilogram = 2.2 pounds.


  • Premium horse feeds are commonly tagged at 0.6 ppm selenium.
  • This is 0.6 mg/kg of feed. This equals 0.273 mg per pound of feed.
  • 0.6 mg/kg divided by 2.2 kg/lb. = 0.273 mg per pound of feed
  • Feeding 5 lbs of this feed per day, results in feeding 1.365 mg per day of selenium.

Vitamins A, D and E are expressed in IU/lb.

  • An IU is an International Unit and is based on the effectiveness of a particular vitamin.
  • There are some rather complicated conversions of different Vitamin sources to International Units, which is why animal requirements are given in International Units, so no further conversion is needed.


  • A feed that lists 100 IU/lb of Vitamin E, fed at 5 lbs per day, provides 500 IU’s per day.

Vitamin C (or Ascorbic acid) and Biotin are normally expressed as mg/lb or milligrams per pound.

  • Usually only tagged on senior horse feeds.
  • Requirements are in mg of intake per day, so no further conversion is needed.


  • A feed that lists 75 mg/lb of Vitamin C, fed at 5 lbs per day, provides 375 mg per day.

Still confused?  Don’t worry about it. Just leave us your questions in the comments section below, and we’ll be happy to help you out!

21 Replies to “Horse Feed Tag Mathematics”

  1. I am in the process of transitioning my horse to Nutrena – I’m starting with the Safe Choice, but I have a bit different problem in deciding on the right feed.
    I have a 16hh 15 year old Shire/TB that I event at Prelim. I need a good quality feed to provide good energy and muscle rebuild qualities but I don’t need weight gain . . . the Shire half looks after that 😉
    Last year the season ended with her just a little more tired than usual. Which food in your line up would you suggest? She is starting back into work after a couple winter months off in the pasture. She is hay feed through the winter, but on pasture in the summer – in what we call our jingle pasture with less grass for part of the day and regular pasture for some of the day.

    1. Hi Laurie, Great question. For her “off season” where you simply want to get quality nutrition without the calories in to her, we would suggest Empower Balance as a great product to sustain her condition and health, without adding weight. As she comes in to the eventing season, you would then have a couple options – continue the Empower Balance and add Empower Boost (high fat rice bran to provide the needed calories for her activity) on top of it, or you could switch to a product such as SafeChoice Original and feed at the low end of the suggested feeding range for her size & activity level. Both would provide the calories and nutrition she needs, while controlling her weight!
      Thank you ~ Roy J.

    1. We formulate to a magnesium minimum in our formulation system considering the nutrient content of all ingredients. Where there is adequate naturally occurring magnesium from ingredients such as wheat midds (0.42% magnesium), alfalfa (0.26% magnesium) and other ingredients, we do not need to add magnesium sulfate or magnesium oxide as a source of added magnesium and the magnesium sulfate or magnesium oxide would not appear on the tag.

      When there is not adequate naturally occurring magnesium from ingredients, we add magnesium sulfate or magnesium oxide to meet our formulation specification and the source of added magnesium would then appear on the tag.

      Thank you ~ Roy

    1. Hello Diana, Thank you for contacting us. Yes, we actually use organic complexed trace minerals in all our premium feeds, which includes the SafeChoice, ProForce, Empower, Pennfields, and Vitality families of products. Organic complexed trace minerals are a step up from chelated trace minerals. In chelated trace minerals, the mineral molecules are tied to general amino acids. In organic complexed trace minerals, the mineral molecule is tied to the specific amino acid that best helps that mineral absorb. For example, zinc is specifically tied to methionine. You can read more here:

      Thank you ~ Gina T.

  2. Dear Roy, Eureka! I found you! I am a sheep owner, but your math explanation is great for evaluating mineral/salt mixes for all livestock owners. Small sheep flock owners who live in areas where sheep are not commonly raised have little to no vet or extension advisors available. Small ruminants are really complex in their needs. Thanks for addressing this important aspect of understanding nutritional science in agriculture.

  3. Hello. I am introducing my 34 year old mare to Empower. Before doing so, I need to determine if she will be getting too much selenium from the Empower and other feed I am using. I hope you can help me determine (1) a safe amount of Empower to feed and (2) if I can eliminate the MiniVite Light. I am currently feeding 5 cups (twice per day) of Dynasty Pro and 1 cup of MiniVite Light (twice per day). Can you help me convert the ppm to pounds as well as suggest if I can eliminate the MiniVite Light? Thank you in advance!

    1. Hi Gloria,
      If this horse is in good body condition and health, I would recommend simplifying the diet and just providing the recommended pounds per day of Empower Balance, and good quality forage, salt and water, assuming the dental health of your horse is adequate to graze/chew forage.

      It would be helpful to know how much 10 cups of Dynasty Pro actually weights (pounds or kg). If you are feeding this product mix to get extra calories in, I would recommend SafeChoice Original or SafeChoice Senior as an alternative to the Empower Balance. If the horse is in good body condition and can consume enough good quality forage, the Empower Balance is fine.

      If Empower Balance is fed per directions, an additional vitamin/mineral supplement should not be required. Water and salt should be available free choice at all times.

      Best of luck!

  4. retired racehorse 6yrs old about to be started on Nutrena Empower Boost High-Fat Rice Bran Horse Supplement. It says feed 1lb per day of the food and we have a 3 quart scooper. How many quarts would he get a day?

    1. Hi Emily,
      Thanks for reaching out! So if you have a 3 qt scoop, that holds about 3 lbs. So knowing how much your horse weighs, activity level and age will help you best determine what rate to feed Empower Boost. We have a great feed rate estimator tool on our website that can be found here: . Scroll to below the Guaranteed Analysis, and you can enter the info specific to your horse to get a recommended feeding rate. Additionally, here is a previous article we posted about feeding scoops and how much they hold, that you may find helpful! .

      Best of luck!

  5. Hi, I have a 20 yr old thoroughbred that I really need to put weight on. I have her on Purina Enrich plus and Hi Pro Natural 14 beet pulp free choice grass hay. I would love to move her to Nutrena. I use your poultry Feather fixer and love how well my poultry does on it. She does low level trail and packing my children around. She has a heart murmur and arthritis. What feed would you suggest gor her? Thank you

    1. Hi Suzanna,
      Great questions, and we are so happy to hear you have had success with our poultry products! It sounds like your horse could benefit from a well-balanced Senior feed. A great option to try would be the SafeChoice Senior Horse Feed It includes great attributes like Topline Balance nutrition, Nutri-Bloom Advantage (which increases fiber digestion up to 15% for better health and bloom, and increased fat level to help maintain energy and ideal body condition. Another great option would be our ProForce Senior Horse Feed This product is high in fat and has a beet pulp based to meet the needs of older horses.

      Best of luck!

  6. Hello , I am concerned I may be feeding more selenium (Se) to my horse than I should be. We currently give 4cps feed (@0.60ppm) with 1-2 oz of another supplement that is (@1.1mg/2oz). Our horse is approximately 11 y/o and about 900 to 1000 lbs. and is worked moderately at the moment. Please help! I just can not wrap my mind around the conversions and the math😳😉 Any advice is much appreciated! Thank you! Horse Hypochondriac

    1. Hello Brooke thank you for your inquiry on Horse Feed Tag Mathematics,

      It sounds like you are a concerned horse owner and want to do the best thing for your horse.
      According to industry supporting literature, Dietary requirements (total diet basis) is 2.4 micrograms Se/kg body weight/day.
      Toxic levels of Selenium (total diet basis) 3.3mg/kg body weight/day (converted is 3300 micrograms Se/Kg body weight/day)
      ppm can be converted with calculations using mg/kg feedstuff. Milligrams can be converted to micrograms by multiplying by 1000 and pounds can be converted to kilograms by dividing by 2.2.

      The math and conversions can be tricky, but are absolutely necessary to be safe when combining feeds, supplements, forages, it is highly recommended to start with the math of what each part of the diet is.
      We would need more information to determine the total Selenium in the diet, but the following should be helpful to help guide your calculations:

      Determine total Selenium in total diet, starting with your forage: we do not know the Selenium content of your forage or the amount you are feeding. Most horses diets are primarily forage, this is a very important part of the calculation. You can get a forage analysis from a reputable lab or NRC does provide some lab approximates for forage types. Legumes or mixed grass NRC range is 0.1-0.36+ppm Se (dry matter basis) most cool season grasses are in the lower range 0.06-0.1ppm Selenium (dry matter basis) other forage types vary.
      Amount of Selenium ppm in forage multiply by total weight of forage(in KG) = mg Selenium, convert to micrograms, multiply by 1000.
      For example if you feed 1% body weight of a forage containing 0.2ppm Selenium and your horse weighs 1000 pounds or 454kg:
      1% of 1000 pounds or 454kg = 10 pounds forage/ 2.2 or 4.54kg forage * 0.2 ppm (or mg/kg) Selenium = 0.90909 mg Se * 1000 = 909.1 microgram Selenium.
      Add the Selenium from forage to your feed concentrate.
      If you are feeding 4cps containing 0.6ppm Selenium (you need to know how much this amount of feed weighs, most feed companies recommend to feed by weight (pounds or Kg) versus volume (cups/litres). please weigh the 4cps to determine the weight of the feed.
      For example: IF your 4cps feed weighs 1Kg or 2.2 pounds this would be: 0.6ppm Se or 0.6mg/kg Se * 1kg feed = 0.6mg Se *1000 = 600 micrograms Selenium.
      The supplement you identify as 1.1mg Se/oz. It is important to know how many ounces supplement per day you are feeding. This is quite concentrated in Selenium.
      For Example: the math on just one ounce of supplement 1.1mg Se *1000 is equal to 1100 micrograms Selenium.
      From the known feed and supplement the Selenium now thus far is 600ug + 1100ug=1700 micrograms Selenium (from 2.2 pounds feed and one ounce supplement).
      If your horse weighs 900-1000 pounds (converted 900/2.2 or 1000/2.2 is equal to 408-454kg).
      Additional calculations for determining horse weight is available on
      If we are using the example and feeding ONLY 2.2 pounds feed and 1oz supplement, those two would equal 1700 micrograms Se/408-454kg body weight = 3.74-4.16 micrograms Se/Kg body weight, which is above adequate according to industry literature.
      It is important to weigh out how much you are feeding (from forage, feed concentrate, supplements and water), convert them to consistent metric units and then determine the total amount of Selenium per kilogram body weight of your horse.
      If your region has high levels of Selenium in the soil, it can be helpful to understand water analysis results as well. Your local University Extension office is likely a good resource for water testing information.

      Best of luck!
      Heidi A.

  7. I have 4 mares that do very little to no work, they get a very small serving of sweet feed ( so they will come when I call) can I safely give them Omega Horse Shine and Gro Strong together, and can I give them a serving of Red Rock mineral salt without causing problems?

    1. Hi Linda,

      Thank you for your question regarding Omega Horse Shine, Gro Strong and Red Rock Mineral Salt. While these are not Nutrena products, use of these products is fairly common. Omega Horse Shine is a good source of Omega 3 fatty acids and can be used according to directions with most diets. Gro Strong minerals from ADM can also be used with most diets. Red Rock Mineral Salt may be appropriate to offer free choice, but I would not suggest force feeding. If the Gro Strong mineral is consumed per directions, the horses will generally consume a free choice salt source to meet additional salt requirement. If they have NOT had access to slat free choice prior to offering, they may over consume initially, so you might want to offer the Red Rock Mineral Salt in limited free choice quantities, 2-4 ounces per head per day, until they have had access to it for a few days. Fresh clean water at above freezing temperature also needs to be available free choice. This is very important at all times and particularly so when a new salt or mineral source is offered.

      You might wan to consider using a ration balancer type product instead of the sweet feed as it sounds like intake is limited. A ration balancer may provide a better source of vitamins and amino acids.

      It is always important to read and follow directions for each product.

      Best wishes,
      Roy J.

  8. Hi! I have a senior HYPP horse. I am not supposed to give him more than 33g of potassium per meal, but not sure what this actually means, as it already takes me several steps to find out the percentage of potassium in forage and grain. So, if I have they % of potassium per day, how do I figure out how much 33g is per meal so I can feed him safely??

    1. Hi Cassandra,
      Hi Cassandra,

      Thank you for your interesting question regarding calculating the potassium intake per meal for your senior HYPP horse. I understand the challenge with complexity of arriving at that number.
      It may be useful to keep a couple of conversion factors in mind. 1 pound = 454 grams and we convert % to decimal fraction when making conversions, so 1% is the same as 0.01.

      If you know the pounds that you are feeding, then you can convert the pounds to grams, then convert % to decimal fraction and do the multiplication. For example, if you are feeding 5 pounds per meal of a senior feed, that would be 5 x 454 =2,270 grams per meal. If the product is 1% potassium, then you would convert 1% to 0.01 as a decimal fraction. The actual amount of potassium would 2270 grams of feed x 0.01 = 22.7 grams of potassium per meal.

      Likewise, if you know you are feeding say 10 pounds per day of feed and 12 pounds per day of forage, you could use the following:
      10 pounds of feed = 4540 grams. 4540 grams x 0.01 = 45.4 grams potassium per day from the feed
      12 pounds of hay = 5448 grams. If the hay is say 0.5% potassium (use the number that you have for your hay) that would give you 5448 x 0.005 = 27.24 grams potassium from hay

      Total potassium per day = 45.4 + 27.24 = 72.64 grams of potassium. If you are feeding 2X per day, that would be 36.32 grams per meal. If your target is 33 grams per meal, you would need to split the feeding into more meals per day to hit your target or adjust what feeds you are using.

      A rule of thumb is also used for HYPP horses is to keep total ration below 1% potassium. In this case, you are feeding a total of 22 pounds = 9988 grams. You are feeding a total of 72.64 grams of potassium, so the total ration is 72.64/9988 = 0.0073 = 0.73% potassium.

      I hope this helps!

      Best wishes,
      Roy J.

  9. Hi-
    I just purchased an 8yo Palomino quarter horse. (I’ll be lessoning and trail riding on him)
    His previous owner gave him a scoop of 12% sweet feed 2x a day. We’d like to get him off of it and onto something to help his topline and generally figure out the best nutrition for him. My daughter’s jumper horses were always under the guidance of her trainer so figuring this out myself is new to me! Any advice would be appreciated. Thanks.

    1. Hi Stef, Thanks for reaching out! Based on what you describe for your new horse, we’d recommend looking at our SafeChoice Original or SafeChoice Special Care – most Nutrena retailers will stock or be able to get either of these easily for you. You’ll want to determine an estimate of how much he weighs (check out this article to determine how to do that), and then you can figure out how much to feed him of whichever product you select at our website – in the “Feeding Directions” section of each product page is a calculator to determine the right amount of feed for his bodyweight and his “light” activity level.

      You’ll want to transition him over a 5-7 day period so as to not cause any digestive upset, then monitor his weight and body condition over time, and adjust his feeding amount as needed to maintain the proper condition. If you feed one of the SafeChoice products, along with a good quality hay and free choice salt, you won’t need to worry about his diet beyond that! Hope that helps, please let us know if you have further questions!

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