How much is one unit of alcohol? And what are the risks of overindulging?

Waiter pours red wine into a wine glass
For a standard-strength wine, just under half a glass - 76ml - is one unit. [Photo: Getty]

Many of us enjoy a glass of wine at the end of a stressful day.

But few likely take the time to work just how many units are in their well-earned tipple.

Confusing guidelines can also leave us clueless about when it’s no longer safe to drive and the health risks of overindulging.

How much is one unit of alcohol?

A single unit is officially 10ml or 8g of pure alcohol.

With this being difficult to picture, DrinkAware breaks it down into approximate measurements for different beverages.

READ MORE: A glass of wine a day may be worse for your heart than binge drinking

For a standard-strength wine of 13% alcohol by volume (ABV), just under half a glass - 76ml - is one unit.

ABV measures the amount of pure alcohol as a percentage of the total volume of liquid.

A 750ml bottled of red, white or rosé therefore contains around 10 units.

For beer drinkers, 250ml - just under half a pint - of a 4% ABV ale equates to one unit.

Cider fans can have marginally less at 281ml, with the tipple typically having a 4.5% ABV.

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When it comes to whiskey - which is high in alcohol at 40% ABV - drinkers can have around half a small shot, with 25ml being one unit.

For spirits like gin, rum, vodka and sambuca, a 35ml measure is 1.4 units, according to the NHS.

And for those with a sweeter tooth, alcopop fans can usually drink up to the neck of the bottle (275ml) before hitting one unit, DrinkAware reports.

How many units should you drink a week? And when can you no longer drive?

Men and women are both advised to have no more than 14 units of alcohol a week.

While it comes down to the size of the glass and strength of the tipple, this equates to around six glasses of wine, six pints of beer and 14 glasses of spirits.

DrinkAware recommends spreading this out over the week, with a few alcohol-free days in-between, rather than bingeing in one go.

The charity also advises sipping on water and snacking between drinks.

A unit is the approximate amount of alcohol our bodies can process in an hour.

In theory, there will be very little or no alcohol in our system 60 minutes after a half glass of standard-strength wine.

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When it comes to getting behind the wheel, English, Welsh and Northern Irish law set the alcohol limit at 35micrograms per 100ml of breath. This gets picked up by a breathalyser.

Scotland is stricter with a limit of 22mcg, which is more in line with other European countries.

There is no foolproof way of guaranteeing it is safe to drive after a few drinks.

The amount of alcohol in your system depends on everything from your age and weight to when you last ate and even how stressed you are, according to DrinkAware.

Drink driving is dangerous due to alcohol delaying our reaction times, while also prolonging how long it takes for messages to reach the brain from the eye.

Processing information also becomes tricky while under the influence.

With even small amounts having an effect, DrinkAware advises you abstain from alcohol completely if you plan on getting behind the wheel.

What are the health risks of drinking too much?

Regularly exceeding the recommended maximum of 14 units of alcohol a week “risks damaging your health”, the NHS warns.

The health service stresses while there is “no safe level of drinking”, but going over the maximum limit could cause a host of issues.

Regularly exceeding 14 units a week has been linked to liver disease, brain damage, heart disease, stroke and damage to the nervous system.

Alcohol is also associated with seven cancers - mouth, upper throat, oesphagus, larynx, breast, bowel and liver, Cancer Research UK reports.

READ MORE: These are the rules of drinking alcohol on public transport

Drinking too much may also damage your mental health, with studies showing a “strong link” between alcohol misuse and self harm, including suicide.

Even a single drinking session can result in injury and poor self control, which can end in you having unprotected sex or getting into a fight.

The NHS also recommends pregnant women, or those trying to conceive, avoid alcohol completely.

Alcohol passes from a pregnant woman’s blood through the placenta to her baby.

A baby’s liver is one of the last organs to develop and therefore cannot process alcohol as effectively as the adult organ.

Drinking during pregnancy - particularly the first trimester - raises the risk of miscarriage, premature birth and a low birth weight.

Alcohol later in pregnancy can lead to learning difficulties and behavioural problems.

In severe cases, babies can develop foetal alcohol syndrome, leading to poor growth and facial abnormalities.

Is some alcohol good for you?

The pros and cons of a glass of wine have long been debated, particularly when it comes to the heart.

Alcohol seems to lower “bad” cholesterol, preventing it forming fatty deposits in the arteries.

It may also stop the formation of blood clots that close off arteries, triggering heart attacks and strokes.

However, there seems to be healthier ways to keep your heart ticking along.

“There are much better ways to change your lifestyle to reduce your risk of heart disease, like stopping smoking, taking more exercise and eating a healthier diet, which don’t carry risk and are much better for your overall health,” Dr Fiona Sim, chief medical adviser at DrinkAware, told the British Heart Foundation.

Drinking within guidelines may protect against non-fatal heart attacks, i.e. those that do not kill you.

However, even low amounts of alcohol has been linked to liver disease and some cancers.

“A healthy diet, taking regular exercise, stopping smoking are all much better for your health than alcohol even in moderation and no one should think about using alcohol as a protector against coronary heart disease, because alcohol can make other problems for you,” Dr Sim said.

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