Metrication

Metric made easy

For more than 40 years measurements in British recipes have been given in Imperial and metric units. Many English-speaking countries, such as Canada, South Africa, Australia and New Zealand now only use metric measures. In line with EU legislation, more and more foods in the UK are sold in metric units. So now it makes sense to cook in metric. If you can count in 5s, 10s and 100s, then cooking in metric is simple.

 

FAQ about metrication and cooking

What are metric units?

Weight measurements are in grams (g) and kilos (kg). Volume and liquid measures are in millilitres (ml) and litres (l). Linear measures are in millimetres (mm), centimetres (cm) and metres (m). There are 1000 g in 1 kilo, 1000 ml in 1 litre, and 1000 mm in 1 metre. Sometimes liquid measures are also described in centilitres (cl), e.g. on a bottle of wine, or even in decilitres (dl). There are 100 cl to a litre and 10 dl to a litre. You may also see liquids written as fractions of litres, e.g. ¼, ½ and ¾ litre.

 

How do I measure in metric?

Easy - just look at your scales and measuring jugs. Most scales and jugs carry both sets of measurements. Metric linear measures are already on rulers and tape measures.

 

How do I cook metric?

We advise you not to try to convert to or from Imperial recipes. It only adds to the confusion. If a recipe calls for 100 g sugar and 300 ml milk, then simply look at the relevant metric unit on your scales or measuring jug. Electric oven temperatures have been in Celsius (centigrade) for many years.

 

What about cake tins and bowl sizes?

Generally these will be expressed in cms and litre sizes, e.g. a 20 cm sandwich cake tin (approx. 8 inch) or 1 litre pudding basin (approx. 1¾ pint). If in doubt, simply measure your existing tins and bowls and note the metric size. There is no need to buy new ones.

 

What about jams and jellies?

In the absence of specific recipes, as a general rule, we recommend you now think in terms of 500 g sugar to each 500 ml (½ litre) of fruit pulp or juice instead of the old guideline of 1 lb of sugar to each pint.

 

What about my favourite old Imperial recipes?

There is no reason to convert them into metric. You already have dual measurement scales and jugs, so follow your recipes as before. You may find that as all foods such as butter, flour, sugar, etc. are sold in metric units you might have some ingredients left over after measuring, but that is all. Below you will find a chart of equivalent measures to help you work out your initial shopping list.

 

Spoon sizes

Metric spoon sizes are 15 ml, 10 ml and 5 ml. As these are so close to existing spoon sizes, and in line with European practice, we recommend the continued use of tablespoons, dessertspoons and teaspoons.

 

How do I calculate the roasting times for meat?

Supermarkets sell meat in decimal divisions of a kilo. So 500 g of meat will be expressed as 0.5 kg. As examples, for a 1.5 kg joint, simply multiply the cooking time given in the chart below by one and a half, or for a 2.2 kg joint by two and a quarter.

Roasting times: oven temperature − Gas Mark 4 or 180°C

Beef

rare

35 minutes per kilo plus 20 minutes

 

medium

55 minutes per kilo plus 25 minutes

 

well done

65 minutes per kilo plus 30 minutes

Pork

 

65 minutes per kilo plus 30 minutes

Lamb

 

55 minutes per kilo plus 35 minutes

Chicken

 

50 minutes per kilo plus 20 minutes

Whole salmon

up to 2.5 kilos

20 minutes per kilo

 

over 2.5 kilos

16 minutes per kilo

 

Metric/Imperial weight conversion

The Guild of Food Writers recommends the sole use of metric units in recipes. If conversions are required, we suggest they are led by metric modular units rather than Imperial to be in line with the metric units in which packaged foods are now sold. From 2000, fresh foods sold loose will also be in modular metric units.

 

Comparisons may confuse. Use either metric or Imperial measures. Do not mix the two.

5 g

1/8 oz

10 g

¼ oz

15 g

½ oz

25/30g

1 oz

35 g

1¼ oz

40 g

1½ oz

50 g

1¾ oz

55 g

2 oz

60 g

2¼ oz

70 g

2½ oz

85 g

3 oz

90 g

3¼ oz

100 g

3½ oz

115 g

4 oz

125 g

4½ oz

140 g

5 oz

150 g

5½ oz

175 g

6 oz

200 g

7 oz

225 g

8 oz

250 g

9 oz

275 g

9¾ oz

280 g

10 oz

300 g

10½ oz

325 g

11½ oz

350 g

12 oz

375 g

13 oz

400 g

14 oz

425 g

15 oz

450 g

1 lb

500 g

1 lb 2 oz

550 g

1 lb 4 oz

600 g

1 lb 5 oz

650 g

1 lb 7 oz

700 g

1 lb 9 oz

750 g

1 lb 10 oz

800 g

1 lb 12 oz

850 g

1 lb 14 oz

900 g

2 lb

950 g

2 lb 2 oz

1 kg

2 lb 4 oz

1.25 kg

2 lb 12 oz

1.3 kg

3 lb

1.5 kg

3 lb 5 oz

1.6 kg

3 lb 8 oz

1.8 kg

4 lb

2 kg

4 lb 8 oz

2.25 kg

5 lb

2.5 kg

5 lb 8 oz

2.7 kg

6 lb

3 kg

6 lb 8 oz

 

Metric/Imperial volume conversion

Spoons: The Guild of Food Writers recommends the continued use of teaspoons, dessert spoons and tablespoons as they are more user friendly than ml spoons.

1.25 ml

¼ tsp

2.5 ml

½ tsp

5 ml

1 tsp

10 ml

2 tsp

15 ml

1 tbsp / 3 tsp / ½ fl oz

30 ml

2 tbsp / 1 fl oz

45 ml

3 tbsp

50 ml

2 fl oz

60 ml

4 tbsp

75 ml

5 tbsp / 2½ fl oz

90 ml

6 tbsp

100 ml

3½ fl oz

125 ml

4 fl oz

150 ml

5 fl oz / ¼ pt

175 ml

6 fl oz

200 ml

7 fl oz / 1/3 pt

225 ml

8 fl oz

250 ml

9 fl oz

300 ml

10 fl oz / ½ pt

350 ml

12 fl oz

400 ml

14 fl oz

425 ml

15 fl oz / ¾ pt

450 ml

16 fl oz

500 ml

18 fl oz

568 ml

1 pint

600 ml

20 fl oz

700 ml

1¼ pint

850 ml

1½ pint

1 litre

1¾ pint

1.2 litres

2 pints

1.3 litres

2¼ pints

1.4 litres

2½ pints

1.7 litres

3 pints

2 litres

3½ pints

2.5 litres

4½ pints

2.8 litres

5 pints

3 litres

5¼ pints

 

Metric-Imperial linear conversion

2 mm

1/16 in

3 mm

1/8 in

5 mm

¼ in

8 mm

3/8 in

10 mm / 1 cm

½ in

15 mm

5/8 in

2 cm

¾ in

2.5 cm

1 in

3 cm

1¼ in

4 cm

1½ in

4.5 cm

1¾ in

5 cm

2 in

5.5 cm

2¼ in

6 cm

2½ in

7 cm

2¾ in

8 cm

 3¼ in

9 cm

3½ in

9.5 cm

3¾ in

10 cm

4 in

11 cm

4¼ in

12 cm

4½ in

13 cm

5 in

14 cm

5½ in

15 cm

6 in

16 cm

6¼ in

17 cm

6½ in

18 cm

7 in

19 cm

7½ in

20 cm

8 in

22 cm

8½ in

23 cm

9 in

24 cm

9½ in

25 cm

10 in

26 cm

10½ in

27 cm

10¾ in

28 cm

11 in

29 cm

11½ in

30 cm

12 in

31 cm

12½ in

33 cm

13 in

34 cm

13½ in

35 cm

14 in

37 cm

14½ in

38 cm

15 in

39 cm

15½ in

40 cm

16 in

42 cm

16½ in

43 cm

17 in

44 cm

17½ in

46 cm

18 in

48 cm

19 in

50 cm

20 in