1. Start with a defensible adult body weight
A recent scale weight is best. If a scale is unavailable, label any measurement result as an estimate and record the method. HayRatio’s adult weight estimator uses horse type plus girth, body length, height, and neck circumference from reviewed University of Minnesota equations.
2. Keep the range visible
University of Minnesota Extension describes 1.5%–2.5% of body weight in total daily feed, with 2% a common planning target. For a 1,000 lb adult horse, that produces 15–25 lb per day and 20 lb at 2%. Because the cited range includes forage plus grain, other feed must be considered before treating the number as hay.
| Adult weight | 1.5% | 2% | 2.5% |
|---|---|---|---|
| 800 lb | 12 lb | 16 lb | 20 lb |
| 1,000 lb | 15 lb | 20 lb | 25 lb |
| 1,200 lb | 18 lb | 24 lb | 30 lb |
| 500 kg | 7.5 kg | 10 kg | 12.5 kg |
3. Choose and document a planning target
The owner selects the percentage; HayRatio does not prescribe it. Record why it was chosen, who reviewed the feeding plan, and when it should be reassessed. Forage analysis, pasture, body condition, workload, and climate can all change individual needs.
4. Weigh representative bales and flakes
Bale and flake size are not stable units. Weigh several bales from the lot and use an average. If caretakers portion flakes, weigh representative flakes rather than assuming each section is equal.
5. Run more than one waste scenario
The formula divides required usable hay by the usable fraction. At 10% waste, 600 lb usable requires 600 ÷ 0.90 = 666.7 lb purchased. The University of Minnesota source reports wide waste differences by feeder and storage setup, so scenario testing is more honest than a universal default.
6. Round purchases up to whole bales
Divide the waste-adjusted total by average bale weight, then round up. That step connects the continuous weight calculation to the discrete units a supplier sells.
7. Leave a caretaker handoff
Write weighed morning and evening amounts, the plan date, owner and veterinary contacts, and instructions for the specific scale, feeder, or net. Avoid writing an ambiguous flake count without its measured average. Use HayRatio’s printable stall card for a local-only handoff.
8. Review when circumstances change
Recheck the plan when the horse, pasture, hay lot, analysis, workload, weather, body condition, or other feed changes. A stored plan is a dated assumption set—not a permanent prescription.
Planning guide questions
What information should I write down before buying hay?
Record each horse’s known or estimated adult weight, the user-selected planning percentage, planning days, average measured bale weight, expected waste scenario, price per bale, and the source/formula version.
How often should a hay plan be reviewed?
Review it when weight, body condition, workload, pasture, hay lot or analysis, health status, weather, or other feed changes. Confirm material feeding changes with a veterinarian or qualified equine nutritionist.
Formula/source contract HR-FORAGE-2026.08.31. See Sources for titles, versions, links, and use notes.