Does this understand fractions like "1/2 cup"?

No — only a plain leading number (e.g. "0.5 cup") is recognized and scaled; a line starting with a fraction passes through unchanged.

Recipe Scaling Calculator

Scale a recipe’s ingredient quantities up or down for a different serving size.

Ingredients (one per line)

Original servings

Target servings

300 g flour
150 g sugar
3 eggs
1.5 tsp vanilla

1
Paste your ingredients

One per line, e.g. "200 g flour" — the leading number is scaled.
2
Set original and target servings

Every quantity is scaled by the same ratio.

Does this understand fractions like "1/2 cup"?: No — only a plain leading number (e.g. "0.5 cup") is recognized and scaled; a line starting with a fraction passes through unchanged.