Grocery Unit Prices Guide

A practical way to compare package sizes without confusing checkout price with the cost of what you use.

Start with one comparable unit

Two rice bags can be compared per 100 g, two oil bottles per 100 ml, and two packs of identical wraps per wrap. Comparing a bottle's milliliters with another product's grams is not a fair conversion unless you know the ingredient's density. Different formulations, flavors, processing and ingredients can also make a price comparison incomplete.

A simple comparison you can check yourself

Imagine a 500 g bag priced at 300 and a 1 kg bag priced at 550. Convert 1 kg to 1,000 g. The smaller bag costs 300 ÷ 500 = 0.60 per gram, or 60 per 100 g. The larger bag costs 550 ÷ 1,000 = 0.55 per gram, or 55 per 100 g. The larger bag saves 5 per 100 g; 5 ÷ 60 × 100 is about 8.33%. These prices are invented for the arithmetic example.

Account for the edible amount

Net weight can include liquid you discard. A hypothetical 400 g can with 240 g of drained beans yields 60% usable weight. At a price of 180, the cost is 180 ÷ 240 × 100 = 75 per 100 g of beans, rather than 45 per 100 g of total contents. Use the label's drained weight if that matches your preparation. If you use all the liquid as well, a drained-only comparison may not match your use case.

Discounts need the final payable price

A package marked 20% off an original price of 500 costs 400 before any other charges: 500 × 0.8. If a promotion requires buying several packages, divide the total payable amount by the total quantity received. A three-for-two offer on equal 500 g packages priced at 300 each gives 1,500 g for 600, or 40 per 100 g. Check eligibility and whether the promotional items are actually the same size.

Bulk savings can disappear through waste

A 1,000 g package priced at 550 is cheaper per gram than the smaller bag in the first example. But if you only use 700 g and discard the rest, the effective cost becomes 550 ÷ 700 × 100 = about 78.57 per 100 g consumed. That exceeds the smaller bag's 60 per 100 g. This is a budgeting illustration, not a prediction of how much food you will waste.

Keep a small comparison record

Write down the store, date, exact product, payable price, net quantity and usable quantity. Prices change, so label a saved comparison with its date. Include delivery or travel only when they are relevant to the purchase decision, and avoid counting a shared fee in every item.

A useful shopping rule

Choose the package that fits both your planned use and your budget. Unit price can identify a potential saving, but it cannot decide whether you like the product, can store it safely or will finish it. Use the grocery unit-price calculator for the comparison and the recipe-cost calculator for the amount consumed in a meal.