数量 and 分量: order quantities and amounts of ingredients
Compare product quantities, ingredients, and text length, without turning a serving count such as 二人分 into a number of ingredients.
Checking the number or amount of objects
数量, read すうりょう, means the number or amount of goods. 注文する商品の数量を確認しました。 says that the quantity of goods to order was checked.
数量を十個から五個に変更しました。 says that the quantity was changed from ten to five items. から identifies the old quantity and に the new one.
The amount to use or the overall volume
分量, read ぶんりょう, means an amount of material or content. 砂糖の分量を少し減らしました。 says that the amount of sugar was reduced slightly.
二人分の材料を用意してください。 asks for ingredients for two people. 二人分 uses the number of servings as its basis; it does not mean two ingredients.
Using the word for content as well
説明の分量を減らして、要点を残しました。 says that the explanation was shortened while the main points were kept. 分量 is not limited to cooking ingredients.
The ranges partly overlap across quantities of goods, ingredients, and text. Read the unit and object together to determine whether the measure is a count, weight, or length of writing.
Does 二人分の材料 mean two ingredients?
Show the answer and why
No. It means ingredients for two people. Check separate instructions for the count or weight of each ingredient.