A standard 175ml glass of wine at 12% ABV contains about 2.1 units of alcohol. But that number shifts depending on the size of your glass and the strength of the wine, so a single glass could contain anywhere from 1.5 to 3.3 units.
How Units Are Calculated
One UK alcohol unit equals 10ml (or 8g) of pure alcohol. That’s roughly the amount your body can process in one hour. To work out the units in any drink, multiply the volume in millilitres by the ABV percentage, then divide by 1,000.
For a 175ml glass of 12% wine: 175 × 12 ÷ 1,000 = 2.1 units. Once you know the formula, you can apply it to any glass size or wine strength.
Units by Glass Size
Wine is typically served in three glass sizes in the UK. Using 12% ABV as a baseline:
- Small glass (125ml): 1.5 units
- Medium glass (175ml): 2.1 units
- Large glass (250ml): 3.0 units
A large glass is a third of a standard 750ml bottle, so just three large glasses finishes the bottle. That same bottle contains roughly 9 units at 12% ABV, or 10 units if the wine is closer to 13.5%.
Many restaurants default to a 175ml pour, but it’s worth checking. If you’re served a 250ml glass of a fuller-bodied wine at 14%, you’re looking at 3.5 units in a single glass, nearly a quarter of the recommended weekly limit.
How Wine Strength Changes the Count
Not all wines are 12%. ABV varies widely by style, and that variation makes a real difference to your unit count.
Light white wines like Pinot Grigio and Sauvignon Blanc tend to sit in the 8% to 12% range. A 175ml glass of a 10% Pinot Grigio comes to 1.75 units. Fuller-bodied whites like Chardonnay are stronger, typically 12.5% to 14.5%, which pushes a medium glass to between 2.2 and 2.5 units.
Red wines generally run higher. A Merlot or Cabernet Sauvignon at 13.5% in a 175ml glass gives you 2.4 units. Bolder reds like Shiraz or Zinfandel can reach 15% or more, meaning a single medium glass could hit 2.6 units.
Dessert wines, including Moscato and late-harvest Rieslings, range from 10% to 20% ABV, but they’re usually served in smaller portions (around 75ml to 100ml), which keeps the unit count roughly comparable to a regular glass.
Fortified Wines: Port and Sherry
Port and sherry are typically 17% to 20% ABV and served in smaller measures, usually around 50ml. A 50ml glass of port at 20% contains 1.0 unit. A 75ml glass of sherry at 17% comes to about 1.3 units. The smaller serving size offsets the higher alcohol content, but it’s easy to pour more generously at home than a bar would.
How This Fits the Weekly Guidelines
The UK Chief Medical Officers recommend no more than 14 units per week to keep health risks low. That guideline is the same for men and women. To put it in practical terms, 14 units is roughly equivalent to six medium glasses of 12% wine, or just under one and a half bottles spread across the week.
Spacing matters too. Drinking those 14 units over one or two evenings carries higher risks of both long-term illness and injury compared to spreading them across several days. If you’re having wine with dinner most nights, even two medium glasses (4.2 units) adds up to over 14 units by Thursday.
Quick Reference for Common Wines
- Pinot Grigio (10%), 175ml: 1.75 units
- Sauvignon Blanc (12%), 175ml: 2.1 units
- Chardonnay (13.5%), 175ml: 2.4 units
- Merlot (13.5%), 175ml: 2.4 units
- Shiraz (14.5%), 175ml: 2.5 units
- Port (20%), 50ml: 1.0 unit
Check the label for the ABV, measure your pour, and the formula does the rest: ml × ABV% ÷ 1,000. Home pours tend to be larger than pub measures, so if you’re tracking your intake, it’s worth using a measuring cup at least once to see what your usual glass actually holds.