Recipe Scaler / Multiplier

Yes — it recognizes whole numbers, decimals, simple fractions (1/2), and mixed numbers (1 1/2) at the start of each line and scales that number, then re-displays it as a friendly fraction where possible.

Generally yes for doubling or halving, but very large scale-ups (4× or more) can throw off leavening, salt, and bake time in ways that aren't purely proportional — large batches often need some manual adjustment and a longer or shorter bake time.

Yes, enter 1 as the desired servings and 4 as the original, and every ingredient will be scaled to one quarter.