What the ONS producer price index tells you about your input costs

The Office for National Statistics publishes a Producer Price Index each month: what UK manufacturers charge for their output, and what they pay for their inputs, broken down by industry classification. It is free, it is public, and your supplier can look it up as readily as you can. That is exactly what makes it useful in a price conversation.

Finding the series that applies to you

PPI is published per CPA class. Corrugated paper, paperboard and containers is C1721. Plastic products is C222. Basic metals is C24. Each has separate series for output prices sold domestically, for exports, and for imports, and they do not move together — imported board can rise while domestic output prices are flat.

Each series has a four-character identifier. They are not guessable and a plausible wrong one looks exactly like a right one, so it is worth checking the title the ONS gives it rather than the code alone.

Three ways people misread it

Treating it as a target price

An index is a measure of movement, not a valuation. "The index says 131.4, so my cases should cost..." has no arithmetic behind it. What you can say is: the index for this category has fallen 3.1% since January and my price has not changed. That is a fact, it is checkable, and it is a reasonable thing to raise.

Ignoring the lag

PPI is published about three weeks after the month it describes, and the Services PPI runs a quarter behind. When you cite a figure, say which month it covers. A supplier who knows the market turned last month will otherwise think you are behind rather than making a point.

Assuming a series is still alive

This is the one that catches people. The ONS retires series without retiring their web pages. A discontinued series will serve you a complete, well-formed, entirely plausible dataset whose last observation is several years old, with nothing on the page saying so.

Worse, some series exist twice — under an older dataset and a current one, with the same code and the same title — and only one of them is still being updated. Always check the date of the most recent observation before you quote a movement to anybody.

One index rarely explains one price

A corrugated case is mostly board, partly energy and partly freight. Weighting those together gives a far more honest picture than the board index alone, and it stops you claiming the market has moved when only one input has.

It also means that when one of those series stops publishing, you genuinely know less than you did — not that the remaining inputs now explain the whole cost.

How to use it in a conversation

Name the series, the source, the two periods you are comparing and the publication lag. Then ask a question rather than making a demand. Something like: the ONS output price index for corrugated containers has fallen 3.1% between January and June — is there room to review our price?

A supplier can check every word of that in about a minute, which is what makes it land as reasonable rather than as a negotiating tactic.