The trolley audit: find the leaks in 30 days

Most households do not have a spending problem. They have a visibility problem.

You know what you earned. You know roughly what you spent. But ask which three items ate the most grocery money last month, and most people guess wrong. The trolley audit fixes that in 30 days — with receipts, not willpower.

What you need

• Every grocery slip for 30 days. Paper in an envelope, or photos in a folder on your phone.
• A simple table. A notes app or a sheet with six columns: date, shop, item, pack size, price, unit price.
• Fifteen minutes a week. That is the whole commitment.

Week 1 — collect without judging

The only goal this week is capture. Do not change what you buy; you are measuring the baseline, not dieting.

Rules that make the data usable:

• Ask for the slip even at self-checkout, and photograph it before it fades.
• Keep household items (soap, washing powder) in the same record but mark them — they are not food, and they distort food totals.
• Note promotions on the slip or in the margin. A promo price is data, not a mistake.

Week 2 — build your baseline

Pick 10 items you buy most often. Staples, not one-offs: maize meal, oil, bread, milk, sugar, rice, chicken, eggs, tea, washing powder.

For each purchase, record the unit price — per kg, per litre, per 100 g. This is the column that makes the audit work; shelf prices lie across pack sizes.

At the end of the week, sort by monthly spend, not by how often you bought. The top three lines are where the money is.

Week 3 — find the leaks

Four leaks show up again and again:

1. Promo creep. Items bought because they were "on special" but not on the list. Count them. The total is usually surprising.
2. Pack-size drift. The same product, smaller pack, same price. Unit price reveals it; shelf price hides it.
3. Brand drift. A premium brand that crept in for one item and stayed. Compare its unit price with the store brand.
4. Duplicate buying. Two open bottles of oil, three half-used bags of rice. Stock you forgot you had.

Mark each leak with the amount involved. Do not estimate percentages — use the actual difference between what you paid and the cheaper alternative you would genuinely have accepted.

A worked mini-example (illustrative)

Say the month shows: promo purchases you did not plan (P45), a pack-size downgrade on one staple (P25), and one brand swap that could have been store-brand (P15). That is P85 in a month — about P1,020 a year. Your numbers will differ; the point is that the leaks are findable, not theoretical.

Week 4 — set two rules, not ten

Rules fail when there are too many. Pick two that target your biggest leaks:

• "No promo purchases unless they are on the list." The list is the budget.
• "Buy the big bag when the unit price beats the small pack and storage allows."
• Or: "One top-up shop a week, cash limit P150."

Write them down. Put them where you shop — phone note, wallet, fridge door.

Why it works

The audit converts vague intentions ("we should spend less") into measured behaviour ("we spent P85 on unplanned promos"). That is the difference between a resolution and a system.

It also gives you a baseline you can compare against next month — and against the national numbers. If the CPI says food rose 4.5% and your basket rose 8%, you know where to look. We unpacked that comparison in Reading inflation in your own trolley.

Where Breadwinner fits

Breadwinner does the recording for you: every slip is read line by line, with unit costs and history — 7 days free, 90 days on Premium. That turns the 30-day audit into a monthly habit with almost no admin.

If you want the pack-size version of the same lesson first, read The unit-price trap.

Scan your first slip — free, 10 slips a month, no card: app.breadwinner.deals

All amounts in the example are illustrative, not promises. Your basket, your numbers.