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 |