We are all different in various aspects. Just like everyone has slightly different hair or height, the same way cannabinoids effect the body of each person in different ways. The best method to decide your dosage is starting small, about half the dose of the below values and evaluate how it makes you feel, then gradually increase the dose until you achieve your desired result.
These are however still guidelines and there are many other ailments that find benefits from using cannabidiol. It is important to note that the top testing lab in the United States has confirmed that there is no lethal cannabis dosage. However, too much of the substance, as in the case of glaucoma, may create reverse effects. Therefore, we recommend that you start with a low dosage and then gradually increase the dosage until you achieve your desired results. You may talk to your physician or find a doctor who work with cannabis and CBD to discuss your exact needs.
For now, we are looking up to scientists to release dosing schedules for medical marijuana, medicinal hemp, and CBD. Other dietary ingredients in CBD include vitamins, minerals, and herbs and botanicals that supplement the diet well. Apparently, many of these products are on the market and serve various purposes, from enhancing individual focus to flavoring food. FDA will definitely not allow supplement manufacturers to suggest dosages or claim true-to-life benefits. This is exactly the reason why there is no expressed dosage on reputable CBD website.
Side Note: It is expected that 7 years from now (that is 2025), the United States alone will have a dietary supplement market worth $68.22 billion dollars, with CBD being the highest growing segment. (https://www.grandviewresearch.com/press-release/north-america-dietary-supplements-market-analysis)