The Shoebox Audit: Find Your Own Inflation Number Before the January Bills Land

Most of us have a vague sense that things are getting dearer. The weekly shop feels heavier on the wallet, the energy direct debit has crept up, and the broadband bill seems to arrive with a new excuse every year. But vague feelings are hard to budget around. What you need is a number — not a perfect one, just a rough, honest number that reflects your household rather than the national average.

That is where the shoebox audit comes in. It is a half-hour job, ideally done with a mug of tea and a calculator. No spreadsheet expertise required. You are going to dig out six months of receipts and bank statements, sort the regular spending into a handful of boring categories, and work out what has really been rising in your basket. Think of it as gophering through your own paperwork — except this time the digging actually pays you back.

Why the headline rate is not your rate

The inflation figures you hear on the news are based on a representative basket of goods and services bought by an average household. Your household is probably not average. You might rent rather than own, run two cars, have a child in nursery, or spend a fortune on pet food and train fares. Those weights matter. If your biggest monthly cost rises by 15%, a national figure of 3% tells you almost nothing useful.

A personal inflation rate is not an official statistic, and it will not be as precise as the ONS number. That is fine. Its job is to show direction of travel and highlight the lines in your budget that are pulling hardest. It turns a general worry into a shortlist of bills worth attacking.

Step 1: Build a six-month paper trail

Pick a six-month window you can actually cover. If you are reading this in November 2026, May to October is a sensible stretch. It gives you enough time to see patterns without requiring an archaeological dig through the loft.

Gather what you have: till slips from the supermarket, email order confirmations, bank and credit card statements, and any paper bills you still receive. Do not worry about every coffee or corner-shop run. Focus on the regular, repeat spending that makes up the bulk of your month. Bank statements are your safety net — if a receipt has vanished, the transaction is usually there.

You do not need to log every item. You need monthly totals for a few broad categories. A phone note, a notebook, or the back of an envelope is fine. The shoebox is the filing system; the calculator is the analysis.

Step 2: Choose seven boring categories

Keep it simple. Pick categories that cover most of your spending and that you can track without guesswork. A workable list might be:

• Groceries and household essentials
• Energy
• Broadband and mobile
• Council tax
• Transport, including fuel or season tickets
• Insurance
• Personal care and toiletries

You can swap one out if it does not apply. The aim is not a perfect map of your finances. It is a rough sketch of the bills that repeat every month.

For annual or quarterly bills, divide the amount by the number of months it covers so it fits the monthly picture. If your car insurance is £300 a year, treat it as £25 a month. Council tax is usually paid over ten months, so use the monthly instalment for the months you actually pay it, or spread it evenly if that makes comparison easier.

Step 3: Compare the start and the end

Now take your first full month and your most recent full month. For each category, work out the difference in pounds, then divide by the earlier figure and multiply by 100. That gives you a percentage change.

Example: groceries were £400 in May and £440 in October. The change is £40. Divide £40 by £400 to get 0.1, then multiply by 100. That is a 10% rise.

If one month looks odd — a big stock-up before guests arrived, or a month with no energy direct debit — use a three-month average at each end instead. Compare the average of May, June and July with the average of August, September and October. It smooths out the wobbles and gives a fairer read.

To get a rough personal inflation rate, add up the pound increases across your categories, divide by your total spending in the earlier period, and multiply by 100. Do not agonise over precision. A rough number you understand beats a perfect number you never finish.

Step 4: Read the result like a detective

Your personal rate might come out higher or lower than the headline figure. Neither result is a verdict on your spending. It is a clue. Look for the categories that rose more than once, or that rose by a noticeable chunk. Those are the ones to investigate.

If groceries are the culprit, check unit prices and pack sizes. Shrinkflation is real: the same receipt total can hide a smaller bag of pasta or fewer teabags. If energy has climbed, it may be time to check your tariff or direct debit. If insurance has jumped, compare renewal quotes before you automatically accept. If broadband is up and you are out of contract, a quick call can sometimes work wonders.

And remember the fixed costs. Council tax may rise once a year, but it is still part of your personal rate. Knowing it is fixed helps you focus on the bills you can actually move.

A realistic example

Suppose your monthly totals look like this:

That household's rough personal rate is 9.6%, even if the national headline is lower. The useful part is not the single figure. It is the shortlist: energy, insurance and groceries are the lines doing the damage. Those are the ones worth a phone call, a comparison site visit, or a change of buying habits.

Make it a twice-yearly habit

Once you have done the shoebox audit, keep the notes. Repeat it in spring and autumn. You will build a simple baseline and spot changes faster. It is a money admin job, not a life overhaul — and it takes less time than sorting out a single disputed bill.

Your personal inflation rate will never be official. It does not need to be. It just needs to be yours. And once you know which bills are climbing fastest, you can stop guessing and start gophering for savings where they actually exist.