What is a unit of alcohol?
A unit of alcohol is used to measure alcohol intake. One unit of alcohol is equivalent to 10ml or 8g of pure alcohol. This amount is also equal to a 25ml single measure of whiskey (ABV 40%), or a third of a pint of beer (ABV 5-6%) or half a standard (175ml) glass of red wine (ABV 12%).
The number of units contained in an alcoholic drink depends on three factors:
- The volume of the drink
- The percentage of alcohol by volume (ABV)
- The container size or serving measure
Using these factors, the number of units can be calculated as:
Units = (Volume in ml x ABV (%)) / 1000
So a shot of vodka, with an ABV of 40% and a typical volume of 25ml, contains 1 unit of alcohol:
(25ml x 40%) / 1000 = 1 unit
This standard measure allows consistent tracking of alcohol consumption and guidance on safe drinking limits.
What are the recommended daily limits for alcohol units?
Public health agencies provide guidance on maximum alcohol units that should be consumed within a time period to reduce health risks:
| Guidelines | Men | Women |
|---|---|---|
| Daily limit | 3-4 units | 2-3 units |
| Weekly limit | 14 units | 14 units |
Drinking above these limits significantly increases risks to physical and mental health. The limits take into account factors like gender, weight and metabolism which affect alcohol tolerance. Women are advised to drink less than men because they tend to have less body water to dilute the alcohol.
What are standard drink sizes?
Different types of drinks contain different volumes and ABV. Common standard drink sizes and their unit contents are:
| Drink | Typical volume | Typical ABV | Units |
|---|---|---|---|
| Beer/lager/cider | 1 pint (568ml) | 5% | 2.8 |
| Wine | Medium glass (175ml) | 12% | 2.1 |
| Spirits | Single (25ml) | 40% | 1 |
A single measure of a spirit like whiskey or vodka contains around 1 unit. But drink measures are often larger than the standard size, meaning the units mount up quickly.
Does drink type or brand change the alcohol units?
Units of alcohol are generally consistent across different drinks and brands at the same volume:
- A 25ml shot of 40% vodka contains 1 unit, whether it is a cheap brand or premium
- A 175ml glass of 12% wine contains 2 units, whether it is red, white, rose or sparkling
- A pint of lager contains 2-3 units, regardless of the brand
The alcohol content is what determines the units. Marketing terms like double strength or export strength may be misleading – always check the ABV. A wine with 15% ABV will have a higher unit content than one of 12% ABV.
Some discrepancies can occur between bottled and draught drinks due to different serving measures. For example, a bottled lager may contain around 1.5 units but a draught pint 2 units.
What about large wine glasses or cocktails?
Wine glasses now tend to hold 250ml rather than 175ml. This increases the units per glass to 3 rather than 2.1. Those innocuous top-ups also start adding extra units.
Cocktails contain multiple alcoholic ingredients, bumping up the overall units. A mojito can contain 2-3 units compared to 1 for a 25ml spirit. And the glasses they are served in are larger than a single shot.
It’s easy to underestimate units with these drinks. Keeping track of intake by counting drinks becomes more difficult. Measuring volumes and using unit calculators gives a more accurate picture.
What about lower strength drinks?
Lower ABV alternatives are now widely available including:
- Low alcohol beer (0.5-1.2%)
- Low alcohol wine (5-7.5%)
- Pre-mixed cans (0.5-2.5%)
These contain significantly fewer units than their full strength equivalents. However, many still contain at least half a unit per drink, so portions should be monitored. Check the labels for ABV and volume information.
How many calories are in a shot of vodka?
Vodka contains calories from the alcohol content. At 7 calories per gram of alcohol:
- A 25ml shot of vodka contains around 70 calories
- A 50ml double shot contains 140 calories
This is before considering mixers like juice or soda. A vodka mixer can add 100-300 extra calories depending on the ingredients. Neat spirits have the lowest calorie content.
Does a shot of vodka count as one drink?
A single 25ml shot of a spirit like vodka is classified as one drink containing 1 unit of alcohol. It meets the criteria of:
- Being a standard serving size
- Having a defined alcohol strength (around 40%)
- Containing approximately 8g or 10ml of pure alcohol
This applies across all spirit types – whiskey, gin, rum, tequila. They are served as single measures containing 1 unit.
A bottle of spirits holds around 26 standard shots. Consumption should be tracked by the number of shots or mixed drinks.
Is a larger pour always more than 1 unit?
It depends on the volume poured:
- A 50ml double shot of 40% vodka contains 2 units
- A 35ml pour contains around 1.5 units
- A 150ml large glass can hold 6 units
The usual restrictions around recommended intake still apply. Drinking above guidelines increases health risks even if consumed over a longer period.
Larger glass sizes make it easier to underestimate units and drink to excess. Measuring serves using a spirit measure helps keep track.
Does the alcohol from a shot of vodka impact the body differently than other drinks?
There is no difference in how the alcohol is metabolised. Around 20% is absorbed through the stomach and 80% through the small intestines. It is then broken down by enzymes at around 1 unit per hour.
Any type of drink containing the same volume of alcohol will have equivalent effects. However, factors like carbonation speed up alcohol absorption. And congeners (compounds) may worsen hangovers with drinks like whiskey.
The main factors determining impact are:
- Dose – total units consumed
- Speed – drinking pace over time
- Body composition and metabolism
A shot of vodka consumed quickly on an empty stomach gives a faster high than a pint of low strength beer. But over a session the end effect on the body is broadly the same.
How long does a shot of vodka take to metabolize?
A single 25ml shot of vodka at 40% ABV provides 1 unit of alcohol. The average metabolism rate is roughly 1 unit per hour, but this varies between individuals based on:
- Age
- Sex
- Weight and muscle mass
- Genetic factors
- Food intake
- Medications
As a guide, a shot of vodka will take around 1 hour to metabolize completely for the average person. But maximum impairment occurs around the halfway point.
So effects like slowed reaction times, blurred vision and reduced coordination will be at peak around 30 minutes after the shot is consumed. After 3-4 hours, all alcohol should be eliminated.
How long should you wait before driving after a shot of vodka?
Most countries have a maximum legal blood alcohol limit for driving of 20-80mg per 100ml. In the US this is 80mg/100ml or 0.08%. Just one shot puts drivers over this limit.
To definitely sober up after a single 25ml shot of vodka, a person would need to wait:
- 2 hours – to be under 20mg/100ml
- 3-4 hours – to be fully sober near 0mg/100ml
But as a standard rule, it is recommended to avoid driving for at least 6 hours after any alcohol intake. Even with almost no alcohol in the blood, hangover effects may slow responses.
When calculating sober time after multiple shots or drinks, add 1 hour for each additional unit consumed.
Does taking a shot of vodka have any health benefits?
There are no proven direct health benefits to taking shots of vodka or any other alcoholic drink.
Small amounts of alcohol may have protective factors against heart disease and diabetes. However, shots provide a large concentration of alcohol over a short time, which is considered harmful drinking.
Any potential benefits are heavily outweighed by the risks including:
- Addiction
- Cancers
- Liver disease
- Brain damage
- Accidents and injuries
There are significant health benefits from reducing alcohol intake to within guidelines of no more than 14 units weekly. Having several alcohol-free days is ideal for recovery.
Conclusion
A single 25ml shot of a spirit like vodka contains 1 unit of alcohol and is classified as one standard drink. The body metabolizes this amount over around one hour. Consuming shots and other high-strength drinks quickly can cause intoxication and impairment within 30 minutes.
To avoid health risks, men and women are advised to drink no more than 14 units weekly, spread over 3 or more days. There are no evidence-based benefits to drinking shots for health. Instead, the focus should be on moderate intake within guidelines, staying hydrated, and having regular alcohol-free days.
