What is spend-based carbon accounting?

It multiplies money spent in a purchasing category by an average emissions-per-euro intensity for that category, derived from an economy-wide input-output model. It answers 'roughly how much carbon rode in on this spend' without needing supplier-level data, which is why the GHG Protocol lists it as an accepted Scope 3 category 1 and 2 method, specifically for screening and hotspotting rather than precise accounting.

Why does this calculator want spend in EUR?

The underlying intensities come from EXIOBASE 3, a European multi-region input-output database priced in euros. Converting your local spend to EUR before entering it keeps the arithmetic correct — using a euro intensity against an unconverted dollar or ringgit figure would silently misstate the result by the exchange-rate gap. Use the exchange rate on your invoice date, or an annual average for a full-year total.

How accurate is a spend-based estimate?

Order-of-magnitude, not exact. Every euro in a category — say 'chemicals' — is assumed to carry the sector's average carbon intensity, when your specific supplier might be far cleaner or dirtier than that average. Spend-based numbers are best used to rank categories by size and flag where activity-based data collection is worth the effort, not as the final number in a disclosure.

What is the difference between spend-based and activity-based methods?

Activity-based methods multiply a physical quantity — kWh, litres, tonnes, kilometres — by a factor for that specific activity, which is why our electricity, fuel, and freight calculators ask for units rather than money. Spend-based methods substitute money for the physical quantity when you don't have it. The GHG Protocol ranks activity-based data as higher quality; spend-based is the fallback for categories where you only have an invoice total, such as most purchased goods and services.

Which purchasing categories does this cover?

Eight EXIOBASE 3 sectors chosen to span common organizational spend: office equipment and IT, construction work, food products, hotel and restaurant services, air transport services, legal and accounting services, textiles, and general chemicals. If your spend falls outside these categories, leave that field blank rather than forcing it into the nearest one — a wrong category understates or overstates the result more than an honest gap.

Free calculator

Purchased goods & services spend-based calculator

Turn annual spend by category into a Scope 3 screening estimate using open EXIOBASE 3 emission intensities — EUR-denominated, free, with full provenance.

Office equipment & IT (EUR/year)Laptops, monitors, servers, printers, networking gear — purchase spend, not leasing residuals.Construction work (EUR/year)Fit-outs, renovations, new-build contractor spend.Food products (EUR/year)Staff canteen, pantry, catering ingredient purchases — not restaurant bills.Hotel & restaurant services (EUR/year)Business travel accommodation and meals booked as services, not room-nights you track separately.Air transport services (EUR/year)Ticket and charter spend, if you don't already have flight distances for the flights calculator.Legal & accounting services (EUR/year)External counsel, audit, bookkeeping, tax advisory fees.Textiles (EUR/year)Uniforms, linens, branded merchandise.Chemicals (EUR/year)Cleaning agents, lab reagents, process chemicals not covered elsewhere.

Prefer to skip the typing? Upload the bill instead — the numbers get read for you, three documents a day free.

How this calculation works

The formula swaps a physical quantity for a monetary one:

Emissions (kgCO₂e) = annual spend in EUR × sector emission intensity (kgCO₂e/EUR)

Each intensity comes from EXIOBASE 3, an input-output model of the world economy that traces, for a given sector, how much greenhouse gas was emitted across its entire upstream supply chain per euro of output. Multiply your spend in that sector by the intensity and you get an estimate of the emissions embedded in what you bought — not just the direct emissions of the supplier you paid, but their suppliers' suppliers too, averaged across the whole sector.

This is a Scope 3 method. Purchased goods sit in category 1 and purchased services in category 2 of the GHG Protocol's Scope 3 Standard, and both categories explicitly permit the spend-based method when supplier-specific or activity-based data isn't available. For most organizations — companies, nonprofits, schools, agencies — purchased goods and services is one of the largest categories in the full footprint, and spend-based screening is the practical way to get a first number without a supplier engagement programme.

Why EUR, and why "estimate"

Two caveats matter enough to put in the field labels themselves.

EUR-denominated. EXIOBASE 3 prices its sectors in euros, built from European and international trade data. If your spend ledger is in SGD, USD, MYR, or any other currency, convert to EUR before entering a figure — otherwise the intensity is being applied to the wrong currency's worth of spend, which silently inflates or deflates every result by the exchange-rate gap. Use the invoice-date rate for individual purchases or an annual average for a full-year total; either is precise enough for a screening exercise.

Order-of-magnitude estimate, not a disclosure-grade number. A spend-based result assumes every euro in a sector carries that sector's average emissions intensity. Your actual supplier for "office equipment & IT" might run a low-carbon manufacturing line, or a high-carbon one — the average doesn't know which. That is the trade-off spend-based accounting makes: it turns an invoice total you already have into a number, at the cost of precision. Use it to rank which purchasing categories are worth chasing down with real supplier data, not as a final figure to defend line by line.

The intensities we apply

| Category | Intensity (kgCO₂e/EUR) | GHG Protocol category | | --- | --- | --- | | Office machinery & computers | 0.412 | Scope 3 cat. 1 | | Construction work | 0.688 | Scope 3 cat. 1/2 | | Food products | 0.531 | Scope 3 cat. 1 | | Hotel & restaurant services | 0.295 | Scope 3 cat. 2 | | Air transport services | 1.842 | Scope 3 cat. 2 | | Legal & accounting services | 0.087 | Scope 3 cat. 2 | | Textiles | 0.744 | Scope 3 cat. 1 | | Chemicals (n.e.c.) | 0.923 | Scope 3 cat. 1 |

The spread is the point. Legal and accounting services, at 0.087 kgCO₂e per euro, is a labour-heavy sector with a thin physical supply chain — mostly office space and computers. Air transport services, at 1.842, drags in jet fuel combustion across the whole industry, making it more than twenty times as carbon-intense per euro spent. A euro is not a euro, carbon-wise: what you bought matters as much as how much you paid for it.

EXIOBASE 3 is published under a CC BY-SA 4.0 licence by the EXIOBASE consortium, which is what lets us serve these intensities free with attribution — the same open-data approach behind the DESNZ and Ember factors used elsewhere on this site.

A worked example

A mid-size organization pulls its annual purchasing ledger and sorts spend into the categories above: €40,000 on office equipment and IT, €15,000 on food products for its canteen, €25,000 on legal and accounting fees, and €10,000 on air transport for business travel it hasn't tracked by flight distance.

Office & IT: 40,000 × 0.412 = 16,480 kgCO₂e

Food products: 15,000 × 0.531 = 7,965 kgCO₂e

Legal & accounting: 25,000 × 0.087 = 2,175 kgCO₂e

Air transport: 10,000 × 1.842 = 18,420 kgCO₂e

Total = 16,480 + 7,965 + 2,175 + 18,420 = 45,040 kgCO₂e ≈ 45.0 tCO₂e

Two things stand out immediately. First, the €10,000 spent on air transport services outweighs the €40,000 spent on office equipment — spend size and carbon size are not the same ranking. Second, if this organization later gets actual flight distances for that travel spend, the business flights calculator would likely produce a more accurate, activity-based number to replace this screening estimate with — which is exactly how spend-based and activity-based methods are meant to work together.

What this calculator doesn't cover

Categories outside the eight listed. EXIOBASE 3 has far more sectors than we expose here; we picked the ones most organizations actually spend against. Spend in an uncovered category should stay out rather than be forced into the nearest match.
Currency conversion. The calculator takes EUR as entered — it does not convert for you. Get the rate right before you type in the number.
Double-counting with activity-based calculators. If you already have litres for your fleet or kWh for your electricity, use those calculators instead and leave the equivalent spend category blank here, or you will count the same emissions twice.
Supplier-specific variation. The intensities are sector averages; a genuinely low-carbon supplier in a high-intensity sector will look worse here than they actually are, and vice versa.
Capital goods depreciation. Some spend-based frameworks amortise large capital purchases over their useful life rather than counting the full spend in the purchase year; this calculator counts the full annual spend as entered.

Where this fits in your reporting

This is Scope 3 category 1 (purchased goods) and category 2 (capital goods and purchased services) under the GHG Protocol's Scope 3 Standard — the categories that, for most organizations, dwarf everything else on this site combined. The kgCO₂e total feeds the same place regardless of who is reporting it: an ISSB IFRS S2 filing, a GRI 305 disclosure, a CDP questionnaire, or a national reporting code all want a Scope 3 figure built the same way, whether the entity behind it is a company, a nonprofit, a school, or a public agency. Singapore-listed issuers should note that STI constituents add Scope 3 reporting from FY2026, and purchased goods and services is typically the category that number leans on hardest — see the SGX climate reporting deadlines guide for the timeline. When supplier invoices are sitting in a folder rather than a spreadsheet, upload them directly instead of tallying the totals by hand.

Sources

EXIOBASE Consortium, EXIOBASE 3 — multi-region input-output emission intensities (CC BY-SA 4.0): exiobase.eu
GHG Protocol, Corporate Value Chain (Scope 3) Accounting and Reporting Standard — category definitions and the spend-based method: ghgprotocol.org/scope-3-standard
GHG Protocol, Corporate Accounting and Reporting Standard — scope definitions: ghgprotocol.org/corporate-standard

Frequently asked questions

What is spend-based carbon accounting?: It multiplies money spent in a purchasing category by an average emissions-per-euro intensity for that category, derived from an economy-wide input-output model. It answers 'roughly how much carbon rode in on this spend' without needing supplier-level data, which is why the GHG Protocol lists it as an accepted Scope 3 category 1 and 2 method, specifically for screening and hotspotting rather than precise accounting.
Why does this calculator want spend in EUR?: The underlying intensities come from EXIOBASE 3, a European multi-region input-output database priced in euros. Converting your local spend to EUR before entering it keeps the arithmetic correct — using a euro intensity against an unconverted dollar or ringgit figure would silently misstate the result by the exchange-rate gap. Use the exchange rate on your invoice date, or an annual average for a full-year total.
How accurate is a spend-based estimate?: Order-of-magnitude, not exact. Every euro in a category — say 'chemicals' — is assumed to carry the sector's average carbon intensity, when your specific supplier might be far cleaner or dirtier than that average. Spend-based numbers are best used to rank categories by size and flag where activity-based data collection is worth the effort, not as the final number in a disclosure.
What is the difference between spend-based and activity-based methods?: Activity-based methods multiply a physical quantity — kWh, litres, tonnes, kilometres — by a factor for that specific activity, which is why our electricity, fuel, and freight calculators ask for units rather than money. Spend-based methods substitute money for the physical quantity when you don't have it. The GHG Protocol ranks activity-based data as higher quality; spend-based is the fallback for categories where you only have an invoice total, such as most purchased goods and services.
Which purchasing categories does this cover?: Eight EXIOBASE 3 sectors chosen to span common organizational spend: office equipment and IT, construction work, food products, hotel and restaurant services, air transport services, legal and accounting services, textiles, and general chemicals. If your spend falls outside these categories, leave that field blank rather than forcing it into the nearest one — a wrong category understates or overstates the result more than an honest gap.