Index of Production, UK: May 2025

• Monthly production output was estimated to have decreased 0.9% in May 2025; this follows falls in April 2025 (down 0.6%) and March 2025 (down 0.2%).

• The fall in monthly output in May 2025 resulted from decreases in "manufacturing" (down 1.0%) and "mining and quarrying" (down 3.2%); these were partially offset by an increase in "water supply and sewerage" (up 0.8%) and "electricity and gas" (up 0.3%).

• 9 of the 13 manufacturing subsectors saw a fall in May 2025, with the largest negative contribution coming from "basic pharmaceutical products" (down 4.2%); with other negative contributions from "transport equipment" (down 1.3%) and "basic metals and metal products" (down 1.8%).

• The largest positive contribution was from "machinery and equipment not elsewhere classified" (up 3.4%), partially offsetting the monthly fall in manufacturing.

• Production output was estimated to have increased (up 0.2%) during the three months to May 2025, compared with the three months to February 2025; this is mainly because of a weak December and January 2025 level, followed by a strong February 2025. 

• The largest positive contributor to the three-monthly rise in May 2025 came from "water supply and sewerage" (up 3.7%), supported by "manufacturing" (up 0.4%); this was partially offset by decreases in "electricity and gas" (down 2.8%) and "mining and quarrying" (down 1.6%).

All data related to the Index of Production (IoP) are available on our Related data page.

The Index of Production (IoP) uses data from a variety of sources. It is calculated by taking turnover and removing the effect of price changes, or by using direct volume estimates.

Most of these data are collected as "turnover values" through the Monthly Business Survey (MBS). Direct volume series are also collected by the Department for Energy Security and Net Zero (DESNZ), and the International Steel Statistics Bureau (ISSB) for steel industries.

The MBS is fully online. Business owners can log on from any location and submit their data at an appropriate time.

From January 2018, Value Added Tax (VAT) data have also been included for 64 production industries for small-and medium-sized businesses. More information is available in our VAT turnover data in National Accounts: background and methodology.

A comprehensive list of the IoP source data can be found in our Gross domestic product (GDP) data sources catalogue.

Response rates for May 2025

MBS response rates were 74.9% for May 2025, based on forms returned. This accounted for 88.1% of total turnover coverage of the sample population. For further information, see our current and historical MBS (production) response rates dataset.

Quality and methodology

The data reported in IoP bulletins and datasets are estimates that are subject to uncertainty, such as sampling variability and non-sampling error. More information is available in Section 2 of our Uncertainty and how we measure it for our surveys web page.

More quality and methodology information (QMI) on strengths, limitations, appropriate uses, and how the data were created is available in our Index of Production, UK QMI.

Accredited official statistics

These accredited official statistics were independently reviewed by the Office for Statistics Regulation in April 2014. They comply with the standards of trustworthiness, quality and value in the Code of Practice for Statistics and should be labelled "accredited official statistics".

Revisions to Index of Production

In line with the National Accounts Revisions Policy, this release gives data for May 2025 for the first time, with April 2025 open for revision.

We have also included revisions to the monthly data from January 2025 to March 2025 as a result of revisions incorporated in the GDP quarterly national accounts, UK: January to March 2025.

Pausing of Producer Prices publications

Business prices data with corrected chain linking methods have been used in this release for producer price indices (PPI), import prices indices (IPI) and export price indices (EPI). These data have now been used from January 2025 onwards in the monthly GDP dataset.

Corrected service producer price indices (SPPI) have not been included. Further analysis will be made on the corrected SPPI dataset. We intend to include this in our GDP monthly estimate, UK: June 2025 bulletin, and in our GDP first quarterly estimate, UK: April to June 2025 bulletin, publishing on 14 August.

The full implementation of updated business prices data will be managed in line with the national accounts revisions policy, with the full time series update being included in our GDP quarterly national accounts, UK: April to June 2025 bulletin on 30 September 2025, and in our Blue Book 2025 release.

Further information on the chain linking error in the producer prices dataset are detailed in our Methods update for Producer Price Indices (PPI) and Service Produce Prices Indices (SPPI) published on 10 July 2025.

Seasonal adjustment

The monthly estimates of IoP are seasonally adjusted. Seasonal adjustment is the process of removing the variations associated with the time of year, or the arrangement of the calendar, from a data time series.

IoP estimates, as for many data time series, are difficult to analyse using raw data because seasonal effects dominate short-term movements. Identifying and removing the seasonal component leaves the trend and irregular components.

We use the X-13-ARIMA-SEATS approach to seasonal adjustment. Seasonal adjustment parameters are monitored closely and are regularly reviewed. For more information, please see our Seasonal adjustment methodology page.

In our IoP estimates, seasonal adjustment is applied at the industry level. The seasonally adjusted series are aggregated to create estimates by sector and total IoP output. As part of our quality assurance approach, residual seasonality checks are regularly completed by our time series analysis team on both the directly seasonally adjusted series and the indirectly derived aggregate time series.

This topic is explored further in our Assessing residual seasonality in published outputs methodology published 9 May 2025.