Tool
Hay calculator for horses: daily amount and stock
This calculator is being revised. Its results use general rules that have not passed our source review. Do not use them as care advice for your horse.
What it does
- Estimates the weight from heart girth and length, or takes what you know.
- Turns 1.5 to 2.5 per cent of bodyweight into hay a day.
- Adds winter and works out the stock in kilos and bales.
What it doesn’t do
- Doesn’t know the quality of your hay; have it analysed if you want to be precise.
- Doesn’t calculate a ration and says nothing about hard feed.
- Doesn’t weigh your horse: the tape is 5 to 10 per cent out.
What happens to your input
What you enter stays in your browser and in the link, so you can keep or share the result. Nothing is sent to a server; we only count that the tool was used.
Why the numbers online differ
For a 600 kg (1,300 lb) horse you find 9 kg of hay a day online, but also 12 to 18. That comes from three things the sources don’t always say: whether they count dry matter (hay is 85 % dry matter, haylage 50 to 70 %), whether the horse also gets grass or hard feed, and how much it works. The hay calculator counts hay as fed and lets you pick the percentage, so you see where the difference is.
Forage is the base of every ration: a horse is built to chew for many hours a day. Below 1.5 % of bodyweight the stomach stands empty too long (ulcers, wood-chewing, boredom). Unlimited, an easy keeper gets fat. The answer is in between, and you read it off your horse, not the scales.
Estimating weight
Few owners have a weighbridge. The tape formula (heart girth squared, times body length, divided by 11,880 in centimetres; in inches, divided by 330 for pounds) lands within 5 to 10 % for most warmbloods and ponies. For a very stocky or very long horse it drifts more. A weigh tape from the shop does the same with girth only and is rougher.
Measure twice a year (after winter, after summer) and write it down: the change says more than the number.
Questions
My horse lives out all day. How much hay then?
Grass counts as forage. In summer on a good field often none extra; in autumn and winter, when the grass stops growing, you build the hay up to the full amount.
What is a bale?
A small bale weighs 15 to 25 kg (35 to 55 lb); a large round bale 250 to 400 kg. Enter what your supplier delivers; in doubt, weigh one.
Why 10 % waste?
Trodden in, rained on, over the edge of the net: somewhere between 5 and 15 % never reaches the horse. Buy generously; hay in February is expensive.
In Halster
Keep a record of weighed hay portions
Save the agreed hay amount and your weighed portions as a note in Halster.
Install the test version through TestFlight.
Read next
Sources