Find the cheapest option by price per unit

The job

Two package sizes, a bulk refill, and a sale item — which is actually cheapest per gram? Mental division under time pressure is how stores win. This is the comparison a calculator app makes awkward.

Worked example

Item A: 398 yen for 500 g → 0.796 yen/g. Item B: 550 yen for 750 g → 0.733 yen/g. Item B is cheaper, saving about 7.9% versus the more expensive option. The tool marks the cheapest row and reports the gap as a percentage.

Add up to five items — useful when a store brand, a name brand, and a subscription price are all on the shelf together.

Limits

The tool divides and compares numbers only; it cannot tell that "500 g" and "0.5 kg" are the same. Enter quantities in the same unit across all items. For per-serving comparisons (detergent washes, coffee cups), use servings as the quantity — grams compare weight, servings compare use.