UK CPI Inflation September 2026: 3.5%, Up From 3.1% in August

UK CPI inflation was 3.5% in the year to September 2026, up from 3.1% in August, according to Office for National Statistics (ONS) figures published at 7:00am (BST) on Wednesday 21 October 2026. On versus, the prediction on the December figure showed 7.8p for an annual rate of 4.0% to 4.4% at 07:47 UK time on 21 October 2026, the market's estimate of a 7.8% chance.

September was the subject of the other UK inflation prediction on versus, What will the UK's annual inflation rate be?, which now shows as settled; ONS's 3.5% falls inside its band for 3.4% to 3.6%. The December prediction, Where will UK inflation end up?, settles on the figure ONS has scheduled for 7:00am (GMT) on 20 January 2027.

What ONS Published on 21 October

These figures come from the ONS bulletin Consumer price inflation, UK: September 2026.

• The headline: CPI rose 3.5% in the year to September, its highest rate since October 2025, when it was 3.6%. CPIH, a broader measure that adds Council Tax and the costs of owning and living in your own home, rose to 3.6% from 3.3%.
• Month to month: CPI rose 0.4% in September 2026, against 0.0% in September 2025. Because prices rose more than a year earlier, the annual rate went up.
• The driver: ONS says transport, particularly motor fuels, made the largest upward contribution to the rise in the annual rate, and restaurants and hotels the largest offsetting downward one. Petrol averaged 169.5 pence a litre in September, the highest since August 2022.
• Underneath: core CPI, which leaves out energy, food, alcohol and tobacco, rose to 2.8% from 2.6%, while food and non-alcoholic drinks stayed at 1.3%.

In ONS's table the rate was 3.4% in December 2025, then 3.0% in January 2026, 3.3% in March, 2.8% in April and 2.6% in June, before rising to 2.9% in July, 3.1% in August and 3.5% in September.

What CPI Measures

The annual CPI rate compares the prices of a basket of goods and services that households buy with the same month a year earlier. As the Bank of England puts it on its inflation page, inflation of 3% means prices are 3% higher on average than a year before. CPI is the measure the Bank targets, and the Government has set that target at 2%. The same page says that when CPI inflation is more than 3% or less than 1%, the Governor writes to the Chancellor to explain why.

CPIH is a different measure from CPI, so check which column a figure comes from. The US also publishes a "CPI", with its own basket; it says nothing about a UK prediction.

How the Predictions Settle

Every market on versus names the source that settles it before you trade (see what market resolution means). Both UK predictions read the CPI 12-month rate as ONS prints it, to one decimal place, and each answer is a band of that rate. CPIH does not count.

• What will the UK's annual inflation rate be? read the September 2026 rate in six bands, from 2.7% or less up to 4.0% or more. Its end date was 06:59 UK time (BST) on 21 October, a minute before the release, and versus now shows it as settled. ONS printed 3.5%, inside the 3.4% to 3.6% band.
• Where will UK inflation end up? reads the 12-month rate for December 2026, not an average for the year, in the CPI 12-month rate column of ONS's main table, due at 7:00am (GMT) on 20 January 2027 (release page), and can settle once that figure is out. If December is still missing when the January figure is due, the latest month ONS has published decides instead. Its end date is 00:00 UK time (GMT) on 20 January 2027, seven hours before the release.

The December prediction has eight answers: below 1.0%, 1.0% to 1.4%, 1.5% to 1.9%, 2.0% to 2.4%, 2.5% to 2.9%, 3.5% to 3.9%, 4.0% to 4.4% and 4.5% or more. None covers 3.0% to 3.4%, and the rules text does not say what happens if the figure lands in that gap, so read the page before you choose an answer (see how to verify market rules).

At 07:47 UK time on 21 October 2026 the page showed 7.8p for 4.0% to 4.4% and 2.7p for 4.5% or more. At 07:25 UK time on 21 October 2026 the same page showed 48.1p for 3.5% to 3.9%. A price is an estimate at that moment, not a promise, and prices of separate answers need not add up to 100p (how to read market probabilities).

Dates to Watch

UK clocks go back on Sunday 25 October (GOV.UK), so the times below are GMT. One piece of arithmetic helps: the annual rate rises when the monthly change is bigger than in the same month a year earlier, and falls when it is smaller. It is not a forecast.

• Thursday 5 November, 12 noon: the Bank of England publishes its Bank Rate decision and minutes (release page), and its MPC dates list the November Monetary Policy Report for the same day. Bank Rate is 3.75% on its Bank Rate page. In its September minutes, on energy prices as at 14 September, the Bank expected CPI inflation of around 3¾% in the last three months of 2026 and slightly above 4% in the first three months of 2027. Those are quarterly figures, not the December rate. See our guide to the Bank of England decision on 5 November.
• Wednesday 18 November, 7:00am: October inflation (release page). In October 2025 CPI rose 0.4% on the month.
• Wednesday 16 December, 7:00am: November inflation (release page). In November 2025 CPI fell 0.2% on the month. The Bank's next decision follows on Thursday 17 December.
• Wednesday 20 January 2027, 7:00am: December inflation, the figure the December prediction settles on. In December 2025 CPI rose 0.4% on the month.

The October and November figures settle nothing, but each is a fresh reading that can move prices. Release dates can change, so check the ONS release calendar.

Before you trade

You can lose the whole amount you put into a position, but never more: a band the December figure does not land in settles at 0p, and the matching band at 100p. versus is licensed by the UK Gambling Commission under account 101143, which you can check on the Commission's public register. A 2% transaction fee is added on top of the stake and shown before you confirm, and while a market is open you can sell at the current price. Positions settle in ordinary money, not cryptocurrency, and customer money is held separately from company money.

Safer Play is built into the app: deposit limits, loss limits, reality checks, time out and self exclusion, alongside GAMSTOP. The safer play page explains each tool, and how it works follows one position from opening to settlement. Only put in what you are comfortable losing. Prediction markets are entertainment with real money at stake, not a way to make money.

Frequently asked questions

What was UK inflation in September 2026?

CPI inflation was 3.5% in the year to September 2026, up from 3.1% in August, ONS said on 21 October 2026. CPIH, the broader measure, was 3.6%.

Why did UK inflation rise in September 2026?

ONS says transport, particularly motor fuels, made the largest upward contribution. Petrol averaged 169.5 pence a litre in September, the highest since August 2022.

When is the next UK inflation figure?

ONS publishes October inflation at 7:00am (GMT) on Wednesday 18 November 2026. November follows on 16 December and December on 20 January 2027.

Will UK inflation reach 4%?

Nobody knows yet. In its September minutes the Bank of England expected CPI to be slightly above 4% in the first three months of 2027, based on energy prices at 14 September. That is an expectation, not a result, and the Bank's next report is due on 5 November.

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