Bulk discount or smaller pack: compare unit prices
Calculate the price per kilogram or item after coupons and multibuy offers, then decide whether a large package really saves money.
Standardize the quantity first
A 500 g pack for 4.50 costs 4.50 ÷ 0.5 = 9.00 per kg. A 750 g pack for 6.00 costs 6.00 ÷ 0.75 = 8.00 per kg, so the larger pack is cheaper by unit before promotions. Compare the same usable product and unit in the unit price calculator.
Apply the offer to the right price
A 20% coupon on the 500 g pack reduces its price to 4.50 × 0.80 = 3.60, or 7.20 per kg. It is now cheaper by unit than the 750 g pack at 8.00 per kg. A buy-one-get-one offer changes the combined price and quantity; do not simply subtract a percentage twice. Use the discount calculator to check the price after one promotion.
Consider waste and the real basket
The lowest price per unit is not the lowest spend if extra food spoils or an offer forces an unwanted purchase. Check expiration, storage, limits, tax treatment and whether coupons can combine. The unit price guide explains why packs with different sizes need a common denominator.