The short answer
It depends on the size of the glass and whose guideline you use, but it is not risk-free. A small 125 ml glass a day is about 10.5 UK units a week, under the NHS limit of 14; a standard 175 ml glass a day is 14.7, just over it. Canada counts 7 drinks a week as increasingly high risk. The WHO says no level of drinking is safe, and the NCI says one drink a day raises breast cancer risk.
Work it out for your drink
A typical strength is filled in. Check your label.
That is
1.2 US standard drinks
= 2.1 UK units
= 1.7 Irish standard drinks
= 1.2 Canadian standard drinks
Each one is 1.2 × one US standard drink:
Key takeaways
- A glass a day is 10.5 to 21 UK units a week depending on the glass: small, standard or large.
- The NHS calls under 14 units a week "low risk", not "safe", and suggests several drink-free days each week.
- Women who have one drink a day have a higher breast cancer risk than women who have less than one a week (NCI).
- The NHS says the old view that some alcohol is good for the heart has been revised, and red wine has no special protection against cancer.
- The less you drink, the lower the risk: that is the one point the WHO, NHS and NCI all make.
What a glass a day adds up to
"A glass" can mean very different amounts. The NHS counts a small 125 ml glass of 12% wine as 1.5 units, a standard 175 ml glass as 2.1 units and a large 250 ml glass as 3 units. Over seven days that becomes:
- Small glass (125 ml) every day: 10.5 units a week.
- Standard glass (175 ml) every day: 14.7 units a week.
- Large glass (250 ml) every day: 21 units a week.
| Glass | UK units a week | US standard drinks a week | Canadian standard drinks a week |
|---|---|---|---|
| Small, 125 ml | 10.5 | 5.9 | 6.2 |
| Standard, 175 ml | 14.7 | 8.3 | 8.6 |
| Large, 250 ml | 21.0 | 11.8 | 12.3 |
| US glass, 5 fl oz (148 ml) | 12.4 | 7.0 | 7.3 |
How a daily glass compares with drinking guidelines
In the UK, the NHS advises men and women not to drink more than 14 units a week on a regular basis and to have several drink-free days each week. A small glass a day stays under the 14 units; a standard or large glass a day goes over, and drinking every day leaves no drink-free days.
Canada's guidance is stricter. It counts 1 to 2 standard drinks a week as low risk, 3 to 6 as moderate risk and 7 or more as increasingly high risk. A Canadian standard drink is a 142 ml (5 oz) glass of 12% wine, so a glass a day of that size is 7 drinks a week. Our guidelines by country page compares your own week with each country's advice.
The NHS is careful with its words: it calls under 14 units a week "low risk" rather than "safe", because there is no safe drinking level.
The cancer evidence at one drink a day
The National Cancer Institute (NCI) says people who drink alcohol are at higher risk of certain cancers than people who do not, and that even light drinkers can be at increased risk of some. Its example is breast cancer: women who have just one drink a day have a higher risk than women who have less than one drink a week.
The NCI also quotes absolute numbers from the US Surgeon General's Advisory, based on Australian data recalculated in US standard drinks. Among 100 women who have less than one drink a week, about 17 will develop an alcohol-related cancer; among 100 who have one drink a day, 19 will. For men the figures are 10 and 11 per 100. That is a real but modest increase, and it grows with each extra drink.
The WHO's 2023 statement goes further: it says current evidence cannot show a threshold below which alcohol's cancer-causing effects do not start. Our guide to alcohol and cancer covers the full picture.
What happened to "a glass of red is good for your heart"
For years, a daily glass of red wine was described as good for the heart. The NHS now says that previously held position has been revised, and that the evidence for a protective effect from moderate drinking is less strong than previously thought.
The WHO says there are no studies showing that any possible benefit of light or moderate drinking for heart disease and type 2 diabetes outweighs the cancer risk at the same levels of drinking. A researcher quoted in its statement adds that the protective effects some studies suggest are tightly connected to the comparison groups and statistical methods those studies used.
Red wine has no special status for cancer either. The NCI says researchers found no link between moderate red wine drinking and the risk of prostate or colorectal cancer, and a meta-analysis found no difference between red and white wine in overall cancer risk.
Blood pressure, calories and the daily habit
For blood pressure, a 2017 review of 36 trials found that cutting down did not significantly lower blood pressure in people who drank two or fewer drinks a day (of 12 g each); the clear benefit was in heavier drinkers. Our page on alcohol and blood pressure has the details.
Calories add up too. The NHS says a standard 175 ml glass of 12% wine contains up to 158 kcal, which is up to about 1,100 kcal a week at one glass a day, by our arithmetic.
The daily pattern matters as well as the amount. The NHS suggests several drink-free days each week. If a nightly glass has become automatic, our guide on how to stop drinking every night helps break the routine without giving up wine altogether.
Common questions
Is one glass of wine a day OK for women?
A small 125 ml glass a day stays under the NHS guideline of 14 units a week, but the NCI says women who have one drink a day have a higher breast cancer risk than women who have less than one drink a week. Lower risk is not no risk.
Is red wine better for you than other alcohol?
Not for cancer. The NCI reports no link between moderate red wine drinking and lower prostate or colorectal cancer risk, and no difference between red and white wine in overall cancer risk. The WHO says it is the alcohol that causes harm, not the type of drink.
Does a glass of wine a day help your heart?
The NHS says the earlier view that some alcohol was good for the heart has been revised and the evidence for protection is weaker than thought. The WHO says no study shows any heart benefit outweighs the cancer risk at the same level of drinking.
Is it better to have one glass a day or seven on the weekend?
Neither pattern is risk-free. The NHS advises spreading drinking over three or more days if you drink as much as 14 units a week and having several drink-free days. Saving the week up is risky in its own way: the NHS calls more than 8 units in a session for men, or more than 6 for women, binge drinking.
When to get help
This site offers self-help tools and information, not medical advice. Talk to a doctor, or call one of the lines below, if:
- you feel shaky, sweaty, sick or anxious when you haven't had a drink;
- you find it hard to stop once you start, or you want to cut down and can't;
- drinking is causing problems with your health, work or the people close to you.
Before you stop: It can be very dangerous to stop drinking suddenly if you are dependent on alcohol. If you get withdrawal symptoms, get medical help before you try to stop drinking.
Free, confidential helplines
- United States:SAMHSA National Helpline1-800-662-HELP (4357)Treatment referral and information, 24/7.
- United States:988 Suicide & Crisis LifelineCall or text 988Free and confidential support for people in distress, 24/7.
- United Kingdom:Drinkline0300 123 1110The national alcohol helpline, free and in complete confidence. Weekdays 9am to 8pm, weekends 11am to 4pm.
In an emergency, call your local emergency number.
Sources
- Alcohol units. NHS. nhs.uk
- The risks of drinking too much. NHS. nhs.uk
- Canada's Guidance on Alcohol and Health. Canadian Centre on Substance Use and Addiction. ccsa.ca
- Alcohol and Cancer Risk. National Cancer Institute. cancer.gov
- No level of alcohol consumption is safe for our health. World Health Organization, Regional Office for Europe. who.int
- Roerecke M, Kaczorowski J, Tobe SW, Gmel G, Hasan OSM, Rehm J (2017). The effect of a reduction in alcohol consumption on blood pressure: a systematic review and meta-analysis. The Lancet Public Health. PMID 29253389
- Calories in alcohol. NHS. nhs.uk
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