Cooking

Package: COOKING_PACKAGE. Registered by createEngine(); for a slimmer engine, register it explicitly (see choosing packages).

Two things a recipe asks for that are not ordinary conversions: reading an oven’s gas mark, and working out how much of everything to use when you are cooking for a different number of people.

Gas marks

A British gas oven is not marked in degrees. Its dial runs from a quarter up to nine, and each mark stands for an oven temperature: gas mark 4 means 180°C. That makes it a lookup rather than a sum, because the steps are uneven, so there is no formula to apply. Write the temperature and ask for the mark, or write the mark and ask for the temperature.

180C in gas mark // gas 4
350F in gas mark // gas 4
gas mark 4 // 180.00 C
gas 6 // 200.00 C

gas mark 4 and gas 6 mean the same thing, because a recipe writes it both ways. The answer is an ordinary temperature, so it converts onwards like any other.

gas 6 in F // 392.00 F

The answer to in gas mark is text, not a number, because “gas 4” is what the dial says. That also keeps the two fractional settings readable: 110°C is gas 1/4, which is a dial position rather than the number a quarter. Read the other way, gas 1/4 is that one setting, so it stands for its own temperature rather than being a quarter of gas 1.

gas 1/4 in C // 110.00 C
gas 1/2 in C // 120.00 C

The table

These are the standard British figures, as printed on cooker dials.

Gas mark	°C		Gas mark	°C
1/4	110		5	190
1/2	120		6	200
1	140		7	220
2	150		8	230
3	170		9	240
4	180

A temperature between two marks is read as the nearer one, within ten degrees, which is half the widest step in the table. Further out than that is not a gas setting at all, and saying so is more use than naming a mark the oven cannot reach.

300C in gas mark // 300C is not a gas setting: the dial runs from gas 1/4 (110C) to gas 9 (240C)

Mixed numbers

A recipe is written in mixed numbers rather than decimals, so a whole number and a fraction beside it read as the single quantity they are, and carry a unit like any other number.

1 1/2 cups in ml // 354.88 ml
2 1/4 kg in lb // 4.96 lb

The fraction can be one of the characters a keyboard offers, on its own or after a whole number:

½ tsp in ml // 2.46 ml
2 ½ cups in ml // 591.47 ml
¼ // 0.25

and between the two parts reads the same way when a unit follows, which is the spelling that used to answer wrongly: 1 and 1/2 cups was read as one plus half a cup.

1 and 1/2 cups in ml // 354.88 ml

What is deliberately left alone

+ is not and. A sum written as a sum stays a sum, so 1 + 1/2 cups is one plus half a cup, which is a different quantity and an answer nobody should have changed underneath them.

1 + 1/2 cups in ml // 119.29 ml

The hyphenated 1-1/2 is ambiguous against subtraction and is left as the subtraction it reads as, and none of this changes how a fraction prints: 1.5 as fraction is still 3/2. See fractions.

Scaling a recipe

A recipe serves four and six people are coming. What you need is the number to multiply every quantity by, and that is what this gives you.

scale 4 servings to 6 // 1.50
scale 6 servings to 4 // 0.67

The word for what you are counting is yours to choose, and you can leave it out.

scale 4 people to 10 // 2.50
scale 2 to 5 // 2.50

The factor is a plain number, so it multiplies whatever you write beside it, or the line above it.

:factor = scale 4 servings to 6 // 1.50
300g * factor // 450.00 g
200g * factor // 300.00 g

This is a factor, not a recipe parser. It will not read a block of ingredients and rewrite them; it gives you the number, and you apply it to the quantities you care about.

What is not here

Converting an ingredient between cups and grams already works, because the units know what common ingredients weigh, and Fahrenheit to Celsius is an ordinary unit conversion. Neither needed this page.

2 cups flour in grams // 250.78 grams
300g butter in cups // 1.32 cups
180C in F // 356.00 F

gas and scale stay ordinary words everywhere else. They are only read as cooking when the rest of the phrase is there: a number after gas, and a full scale ... to ... around scale. So :scale = 1.5 still defines a variable, and a line about a gas bill is still a line about a gas bill.