Unit Price Cheatsheet (UK) — How to Spot Real Deals

Quick Start

Unit price is the only fair way to compare across sizes and brands. Learn the 3-step method and keep your own target prices so you can spot real deals at a glance.

Why unit price matters

Pack sizes change; the price per kg/100g/L doesn’t lie.
End-caps and multibuys can hide a worse deal.
Once you know targets, you stop overpaying automatically.

The 3-step method (in-store)

1) Find the unit price on the shelf label (per kg / 100 g / L).
2) Normalise if labels differ:

per 100 g → per kg: ×10
per 100 ml → per L: ×10
3) Decide: buy the lowest unit price that still fits your needs (don’t overbuy).

Mini examples

Pasta A – 500 g £0.75 → £1.50/kg. Pasta B – 1 kg £1.60 → £1.60/kg. Pasta A wins.
Tomatoes 400 g £0.45 (×4) vs multipack 4×400 g £2.00 → singles £1.13/kg, multipack £1.25/kg. Singles win.

Build your targets (fill with your local data)

Replace the Xs with figures from your Price Book and update monthly.

Rice (long-grain, own brand): ~£X.XX/kg
Pasta (own brand): ~£X.XX/kg
Chopped tomatoes: ~£X.XX/kg
Oats (rolled): ~£X.XX/kg
Beans (baked): ~£X.XX/kg

Tip: add 5–10 staples your household actually buys.

When “bigger” isn’t cheaper

Shrinkflation (380 g vs 400 g cans) flips the per-kg cost.
Promo tins may be cheaper per tin, not per kg.
Brand tiers: premium can be 2× the unit price of own brand.

Make it habit

Put your targets on your phone notes; compare in seconds.

Track 10 staples in your Price Book (UK) and refresh prices once a month.