Calcium requirements vary depending on the availability of copper in your horse's diet. Therefore, you need to know the actual daily dose required before calculating how long a bag will last.
The feeding of mineral separates should not be undertaken without having your forage, either hay or pasture, analysed and the correct mineral ratios established. If you are unable to carry out a full mineral analysis from all sources of forage and are uncertain of the mineral levels required, we recommend feeding a premixed supplement/balancer instead. Please see the Progressive Earth equine balancers in our shop for more details.