Cannabinoid ratios on a label compare the amounts of two cannabinoids, usually CBD and THC: 1:1 means equal amounts, and 20:1 means twenty times more CBD than THC. The ratio says nothing about the total strength. To know what a product contains, you need the milligrams or percentages on the batch certificate.
Key facts
- What a ratio shows
- The proportion of one cannabinoid to another, not the total amount
- Usual order
- Most labels put CBD first (CBD:THC), but some put THC first; check which
- How to calculate it
- Divide the CBD figure by the THC figure from the certificate of analysis
- Does CBD offset THC?
- Studies are mixed; a 2023 trial found no protective effect of CBD at ratios up to 3:1
- UK rule
- THC is a Class B drug; consumer CBD products must meet the "exempt product" limits (Home Office, as of October 2026)
Prefer watching? This video covers the main points.
What are cannabinoid ratios?
A ratio compares two numbers. On cannabis and hemp products, it usually compares CBD with THC. A 1:1 product has equal amounts of both. A 20:1 product has twenty parts CBD for every part THC.
Some labels compare other cannabinoids, such as CBD with CBG. The principle is the same: the first number belongs to the first cannabinoid named.
How do you read a CBD:THC ratio on a label?
First, check the order. In most markets the label reads CBD:THC, but US dispensary products often give THC first. A study of US products sorted them by THC:CBD ratio (Pennypacker et al., 2022). The same "1:20" can therefore mean opposite things.
Second, look for the absolute amounts. Two 1:1 products can differ tenfold in strength. The ratio only tells you the balance.
Third, check whether the figure is for the product or for the extract inside it. A certificate of analysis usually gives percentages by weight or milligrams per gram of the tested sample.
| Ratio (CBD:THC) | Meaning | Example from a certificate |
|---|---|---|
| 1:1 | Equal amounts | 5 mg CBD and 5 mg THC |
| 2:1 | Twice as much CBD as THC | 10 mg CBD and 5 mg THC |
| 20:1 | Twenty times more CBD | 20 mg CBD and 1 mg THC |
| 1:0 | No THC detected | CBD isolate or THC-free broad spectrum |
How do you calculate a ratio from a certificate of analysis?
Take the CBD value and divide it by the THC value, using the same unit for both. If a certificate shows 10% CBD and 0.2% THC, the ratio is 10 ÷ 0.2 = 50, or 50:1.
Make sure the certificate matches your batch number. If it lists both acid and neutral forms, such as CBDA and CBD, look for a "total" figure. Our guide on how to read a certificate of analysis explains each column, and how hemp is tested for THC covers the methods.
Does more CBD reduce the effects of THC?
The evidence is mixed. A 2019 systematic review of 16 human studies found that CBD reduced some effects of THC in several studies, but not consistently across studies and outcomes, and no clear dose-response pattern emerged (Freeman et al., 2019).
A 2023 randomised trial gave 46 infrequent cannabis users vaporised cannabis with 10 mg THC and 0, 10, 20 or 30 mg CBD. At these ratios, up to 3:1, CBD did not reduce the memory impairment or the psychosis-like symptoms caused by THC (Englund et al., 2023).
So a high CBD:THC ratio does not make a THC product safe. The amount of THC still matters most. Read CBD vs THC for how the two differ.
Why do some products show no ratio?
Many products don't contain THC worth comparing. A study of US online dispensary listings found that 58.5% of products gave no information on CBD content at all (Pennypacker et al., 2022). In the UK, CBD products sold to consumers must stay within the "exempt product" rules, which include a limit of 1 mg of a controlled drug in any one component part (Home Office, 2024). For these products, the CBD content and the THC figure on the certificate matter more than a ratio.
The type of extract also changes what you see on the certificate. Read about full spectrum, broad spectrum and isolate, or the entourage effect for the debate about whether cannabinoids work together.
From our production
We test every batch in Switzerland, and we have never had a failed test since 2013. The certificate for each batch lets you work out the ratio yourself.
— Robin Roy Krigslund-Hansen, co-founder and CEO
Frequently asked questions
What do cannabinoid ratios like 1:1 or 20:1 mean?
They compare two cannabinoids, usually CBD and THC. 1:1 means equal amounts; 20:1 means twenty times more CBD than THC. The ratio says nothing about how strong the product is overall.
Which number comes first, CBD or THC?
Most labels write CBD:THC, but some, especially in US dispensaries, write THC:CBD. Always check the order before comparing products.
How do I work out the CBD to THC ratio?
Divide the CBD value by the THC value from the batch certificate of analysis, using the same unit. For example, 10% CBD and 0.2% THC gives 50:1.
Does a high CBD ratio cancel out THC?
No. Studies are mixed, and a 2023 randomised trial found that CBD at up to three times the THC dose did not reduce THC's effects on memory or psychosis-like symptoms.
Are 1:1 CBD:THC products legal in the UK?
Not as consumer products. THC is a Class B drug, and consumer CBD products must meet the exempt product limits. Products with more THC need a prescription or a Home Office licence.
Related guides
This article summarises published research. It is not medical advice. Formula Swiss CBD oils are sold as cosmetics for use on the skin. They are not food supplements or medicines and are not intended to diagnose, treat, cure or prevent any disease.
Last reviewed:
Sources
- Pennypacker SD, Cunnane K, Cash MC, Romero-Sandoval EA. Potency and therapeutic THC and CBD ratios: U.S. cannabis markets overshoot. Front Pharmacol 2022;13:921493. doi:10.3389/fphar.2022.921493
- Freeman AM, Petrilli K, Lees R, et al. How does cannabidiol (CBD) influence the acute effects of delta-9-tetrahydrocannabinol (THC) in humans? A systematic review. Neurosci Biobehav Rev 2019;107:696–712. doi:10.1016/j.neubiorev.2019.09.036
- Englund A, Oliver D, Chesney E, et al. Does cannabidiol make cannabis safer? A randomised, double-blind, cross-over trial of cannabis with four different CBD:THC ratios. Neuropsychopharmacology 2023;48(6):869–876. doi:10.1038/s41386-022-01478-z
- Home Office. Drug licensing factsheet: cannabis, CBD and other cannabinoids (updated 3 October 2024). gov.uk
- Misuse of Drugs Regulations 2001, regulation 2 (exempt product). legislation.gov.uk
