Data · Scope 3 estimation
Spend-based emission factors: the Defra UK multipliers
The Defra spend-based emission factors are published as the spend-based emissions multipliers, 1997 to 2023, alongside Defra’s UK and England carbon footprint statistics.
They are not the DESNZ conversion factors, and DESNZ says so on the conversion factors’ own publication page.
This page covers what they are, when a spend-based estimate is acceptable, and how to replace it with better data.
Two datasets, often confused
Spend-based multipliers are not the conversion factors
DESNZ’s 2026 methodology paper, ¶1.6, says the conversion factors “differ from the spend-based emissions multipliers currently published by the Department for Environment, Food & Rural Affairs (Defra)”.
Defra’s multipliers are “primarily intended to allow users to compare the carbon intensities of different categories of final UK demand”.
But they “can be used to provide an initial assessment of a user’s full supply-chain emissions based on spending across different goods and services”.
DESNZ adds that users “may wish to use spend-based methods where they do not have sufficient data to use activity-based methods”, and “should ensure they report the methods used”.
The name confusion runs the other way too: many people search for “DEFRA spend-based emission factors” and land on the activity-based DEFRA emission factors 2026, which contain no spend-based factors at all.
| DESNZ conversion factors | Defra spend-based multipliers | |
|---|---|---|
| Converts | Activity: kWh, litres, km, tonnes | Spending on goods and services |
| Published with | GHG conversion factors, every June | UK and England carbon footprint statistics |
| Built for | Company reporting, incl. SECR | Comparing categories of UK demand |
| Typical use | Scope 1, 2 and activity-based Scope 3 | A first estimate of supply-chain Scope 3 |
The dataset
What Defra publishes
The UK and England’s carbon footprint to 2023 page carries the release, its datasets and a methods paper, one of them the spend-based emissions multipliers, 1997 to 2023, as an OpenDocument spreadsheet.
The carbon footprint, in Defra’s words, is the greenhouse gas emissions “associated with the consumption spending of UK or England’s residents on goods and services, wherever in the world these emissions arise along the supply chain”.
The statistical release says the estimates come from a multi-regional input-output model developed for Defra by the University of Leeds, combining economic activity, trade, supply chains and emissions data.
Defra’s summary of methods describes the input-output tables behind the model, built at a 112-sector level for recent years.
That is what the letters EEIO mean in practice: an environmentally extended input-output model that follows a pound of spending back through the economy’s supply chains.
Open the spreadsheet itself for the categories, the units and the year each multiplier relates to; this page does not reproduce values, because a factor should come from the file.
- 30 Jun 2026Annual update
Carbon footprint for the UK and England to 2023.
- 7 Jul 2026Correction to the release text
- 24 Jul 2026Correction to an England table
Geographical coverage of the Summary_2023 tab.
Source: Defra, UK and England’s carbon footprint to 2023 — page history
The test
When a spend-based estimate is acceptable
UK SRS S2 does not ban any input. It tells the entity which to prefer, and to say what it used.
| UK SRS S2 | What it says | What it means for spend-based data |
|---|---|---|
| ¶B38 | Scope 3 "is likely to include the use of estimation"; the approach must give a faithful representation | Estimation is expected, not a failure |
| ¶B40 | Prioritise direct measurement, data from specific value-chain activities, timely data for the right jurisdiction and technology, and verified data | Spend-based data scores low on specificity |
| ¶B47 | "The entity shall prioritise—with all else being equal—the use of primary data" | Supplier data wins where you can get it |
| ¶B49 | Secondary data includes industry-average data from "published databases, government statistics" | Defra's multipliers are secondary data |
| ¶B51 | Prioritise emission factors that relate to the jurisdiction of the activity | A UK multiplier suits UK spend; imports are modelled inside it |
| ¶B52 | Prioritise data that is "timely and representative… during the reporting period" | A 2023 series used for 2027 spend needs explaining |
| ¶B56 | Disclose how much of Scope 3 is measured using specific-activity inputs, and how much using verified inputs | The spend-based share becomes visible |
| ¶B57 | The Standard presumes Scope 3 "can be estimated reliably using secondary data and industry averages" | No excuse for leaving a category out |
So spend-based estimation is legitimate under UK SRS S2, particularly for categories with thousands of small suppliers, provided it is disclosed as what it is.
Paragraph 29(a)(iii) requires the entity to disclose its measurement approach, inputs and assumptions, why it chose them, and any changes during the period.
Under the FCA’s final rules (PS26/19), listed companies in scope report against UK SRS on a comply-or-explain basis for accounting periods beginning on or after 1 January 2027, with one year’s relief from disclosing Scope 3.
How that relief works, and what follows it, is covered in Scope 3 reporting under UK SRS.
The accounting standard
What the GHG Protocol expects
The Scope 3 Standard, §6.2, says companies “shall account for all scope 3 emissions as defined in this standard and disclose and justify any exclusions”.
No category is optional under it; a category a company does not have is reported as zero or not applicable.
The Scope 3 calculation guidance is where calculation methods for each of the 15 categories are described, but it is a companion document: it points to the Standard for requirements rather than creating any.
DESNZ’s own framing points to where spend-based methods help: lines where there is not enough data for an activity-based method, which for most companies means much of what they buy.
Which categories exist, and which UK regime asks for which, is set out in Scope 1, 2 and 3 emissions.
Doing it properly
Currency, inflation and matching categories
Map spend to categories. Each line of spend has to be assigned to one of the dataset’s categories; the mapping is the largest single judgement in the estimate, so document it.
Match the price year. A multiplier describes emissions per unit of spending in a particular year’s prices, and the latest Defra series runs to 2023.
Spending in 2026 or 2027 is expressed in later prices, so deflating it to the multiplier’s year with an official price index is the usual adjustment; without it, inflation alone raises the estimate.
Convert currency first. The UK multipliers describe UK final demand, so non-sterling spend has to be converted before they can be applied.
Strip out what is not a purchase of goods or services. Taxes, internal recharges and items already counted from activity data would otherwise be counted twice.
Keep the method stable. Changing multiplier year, mapping or deflator between years moves the total without any change in what was bought, and UK SRS S2 ¶29(a)(iii)(3) asks for such changes and the reasons.
Neither DESNZ nor Defra publishes a step-by-step method for applying the multipliers to company spend.
What follows is how the arithmetic has to work; state whatever you do in the methodology note.
Which UK rules ask for it
Where purchased goods and services are actually required
| Regime | Purchased goods and services (Scope 3, category 1) | Source |
|---|---|---|
| SECR | Not required: unquoted companies report no Scope 3 beyond transport fuel | SI 2008/410 Sch 7 ¶20D |
| PPN 006 carbon reduction plan | Excluded: five Scope 3 categories only | PPN 006 Technical Standard |
| UK SRS S2 (listed companies, PS26/19) | Comply or explain from 2027; one year's Scope 3 relief; all 15 categories considered | UK SRS S2 ¶B32 |
| GHG Protocol Scope 3 Standard | All categories accounted for; exclusions disclosed and justified | Scope 3 Standard §6.2 |
DESNZ’s own call for evidence on Scope 3 described Scope 3 emissions as remaining “largely voluntary” in UK reporting, and drew 184 responses.
So for most UK companies a spend-based Scope 3 figure is voluntary or investor-driven; the route to a carbon reduction plan is covered in our guide to the carbon reduction plan.
The practical side of building a Scope 3 inventory is in Scope 3 emissions reporting.
From estimate to evidence
Moving from spend-based to supplier data
A spend-based figure is a starting point, and UK SRS S2 is built to reward replacing it.
¶B48 of UK SRS S2 counts “supplier-specific emission factors for purchased goods or services” as primary data, which ¶B47 tells entities to prioritise.
Rank categories and suppliers by their share of the spend-based total, and ask the largest for product- or supplier-specific emission data first.
Where a supplier reports its own emissions but not per product, an allocation by your share of its revenue is a step up from an economy-wide average, and should be described as such.
Track the share of Scope 3 measured from specific-activity and verified inputs each year; ¶B56 asks for it, and it is the clearest evidence that the estimate is improving.
Activity data you already hold, such as freight tonne-kilometres or business travel distance, can move to the activity-based DESNZ conversion factors straight away.
Frequently asked
Questions people ask
Where are the Defra spend-based emission factors?
Defra publishes them as "Spend-based emissions multipliers, 1997 to 2023", a spreadsheet attached to its statistics release "UK and England's carbon footprint to 2023". The latest annual update was on 30 June 2026. They are not in the DESNZ greenhouse gas conversion factors workbook.
Are the spend-based multipliers the same as the DEFRA conversion factors?
No. DESNZ says its conversion factors "differ from the spend-based emissions multipliers currently published by the Department for Environment, Food & Rural Affairs (Defra) alongside the annual UK and England carbon footprint publication". The conversion factors are activity-based, per kilowatt-hour, litre or kilometre; the multipliers turn spending on a category of goods or services into emissions.
What are the Defra spend-based multipliers meant for?
DESNZ says they are "primarily intended to allow users to compare the carbon intensities of different categories of final UK demand", but "can be used to provide an initial assessment of a user's full supply-chain emissions based on spending across different goods and services". It adds that users may use spend-based methods where they do not have enough data for activity-based methods, and should report the methods they used.
What is an EEIO emission factor?
An environmentally extended input-output factor estimates the emissions behind a unit of spending on a product or sector by tracing it through the economy's supply chains. Defra's carbon footprint figures come from a multi-regional input-output model developed for Defra by the University of Leeds, which combines data on economic activity, trade, supply chains and emissions.
Can I use spend-based factors under UK SRS S2?
Yes, as secondary data, but they sit low in the standard's order of preference. UK SRS S2 requires an entity to prioritise direct measurement, primary data from specific activities in its value chain, timely data representing the right jurisdiction and technology, and verified data (paragraph B40). Paragraph B49 lists industry-average data from government statistics as secondary data, and paragraph B57 presumes Scope 3 can be estimated reliably with secondary data and industry averages. The entity must disclose its approach and how much of its Scope 3 rests on primary and verified inputs.
How do I adjust spend-based factors for inflation?
Check the price year the multiplier relates to before applying it. The latest Defra series runs to 2023, so spending in a later year is expressed in different prices; deflating that spend to the multiplier's year with an official price index is a common adjustment. This is our method reasoning, not a DESNZ or Defra instruction, and whatever you do should be stated in the methodology note.
Do UK rules require Scope 3 purchased goods and services?
Not as a general duty. SECR requires no Scope 3 beyond transport fuel for unquoted companies. PPN 006 carbon reduction plans cover five Scope 3 categories and exclude purchased goods and services. Under the FCA's final rules, listed companies in scope report against UK SRS on a comply-or-explain basis from accounting periods beginning on or after 1 January 2027, with one year's relief from Scope 3.
How do I move from spend-based to supplier data?
Start with the suppliers and categories that carry most of the spend-based total, and ask them for product- or supplier-specific emission data. UK SRS S2 paragraph B48 names supplier-specific emission factors for purchased goods or services as primary data, which the standard tells entities to prioritise. Report the share of Scope 3 measured from primary and verified inputs, as paragraph B56 requires.
Sources
Primary sources
Every figure, date and status on this page traces to the instrument’s owner. Secondary commentary is never the source for a number.
- DefraUK and England's carbon footprint to 2023 (statistics collection)
Home of the "Spend-based emissions multipliers, 1997 to 2023" dataset; annual update 30 June 2026.
- DefraSpend-based emissions multipliers, 1997 to 2023 (ODS)
The multipliers themselves.
- DefraCarbon footprint for the UK and England to 2023 — statistical release
Consumption emissions defined; the MRIO model developed for Defra by the University of Leeds.
- DefraUK and England's carbon footprint: summary of methods (2026)
The input-output method behind the multipliers.
- DESNZ2026 conversion factors methodology paper, ¶1.6
How the multipliers differ from the conversion factors, and what DESNZ says they are for.
- DESNZGreenhouse gas reporting: conversion factors 2026
The same distinction on the publication page; report the methods used.
- Department for Business and TradeUK SRS S2, ¶29(a)(iii) and the Scope 3 measurement framework, ¶¶B38–B57
Prioritising inputs; secondary and primary data; disclosure of inputs.
- Financial Conduct AuthorityPS26/19: Aligning listed issuers' sustainability disclosures with international standards
Comply or explain from accounting periods beginning on or after 1 January 2027; one year's Scope 3 relief.
- GHG ProtocolCorporate Value Chain (Scope 3) Standard (2011)
The 15 categories; account for all Scope 3 and justify exclusions (§6.2).
- GHG ProtocolTechnical Guidance for Calculating Scope 3 Emissions
A companion to the Standard: calculation methods, data sources and worked examples, not requirements.
- DESNZUK greenhouse gas emissions reporting: Scope 3 emissions (call for evidence and outcome)
"Scope 3 emissions remain largely voluntary"; 184 responses.
- Cabinet OfficePPN 006 Technical Standard for Carbon Reduction Plans
Five Scope 3 categories; purchased goods and services excluded.
- legislation.gov.ukSI 2008/410 Schedule 7, Part 7A (¶20D)
SECR asks unquoted companies for no Scope 3 beyond transport fuel.