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Employee commuting carbon calculator

Turn a staff commute survey — annual car kilometres by fuel type — into a Scope 3 category 7 commuting figure with transparent, licensed factors.

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How this calculation works

Employee commuting sits in Scope 3, category 7 of the GHG Protocol — the emissions from staff getting themselves to work and home again, in vehicles the organization doesn't own and doesn't fuel. Because no fuel receipt ever crosses your desk for a commute, the GHG Protocol's standard approach is the distance-based method: survey how far people drive, apply an average-car emission factor per fuel type, and multiply.

Emissions (kgCO₂e) = kilometres driven per year × emission factor for that fuel type (kgCO₂e/km)

The only real work is turning a staff survey into annual kilometres, and a short set of questions does it. Each driving employee reports two things they already know:

  1. Their round-trip commute distance in km
  2. Their working days per year on site (a typical full-time pattern is about 20 days a month, so roughly 240 a year)

Then, per driver:

annual km = round-trip km × working days per year

Sum the drivers by car fuel type — petrol, diesel, hybrid, or unknown — and enter the four totals above. No trip diaries, no postcode modelling: just a distance figure built from what employees can report accurately.

The factors, and why we use these

For petrol, diesel, and hybrid cars we apply the UK DESNZ 2025 average-car factors, published as per-kilometre figures for an average vehicle of each fuel type — the standard the GHG Protocol's distance-based method points to when individual fuel-consumption data isn't available:

| Car type | Factor (kgCO₂e/km) | Source | | --- | --- | --- | | Petrol | 0.16272 | DESNZ 2025 | | Diesel | 0.17304 | DESNZ 2025 | | Hybrid | 0.12825 | DESNZ 2025 | | Fuel type unknown | 0.16725 | DESNZ 2025 |

These are average-car factors — they already account for typical real-world fuel consumption across the vehicle fleet of that type, so unlike the fuel-based method used for fleet fuel, no separate consumption figure is needed here. Diesel cars carry the highest per-km factor of the three known fuel types; hybrids the lowest, reflecting their partial electric drive. The "fuel type unknown" factor sits close to the fleet average and is meant as a fallback, not a first choice — use petrol, diesel, or hybrid whenever the survey response tells you which one applies.

The DESNZ factors are published under the Open Government Licence v3.0, which is what lets us serve them free with attribution. The exact factor, source, year, and licence used are printed under your result — if an auditor or customer asks where the number came from, the provenance is already in your hands.

A worked example

Start with one driver: a petrol car doing a 25 km round-trip commute, 20 working days a month — 240 days a year.

25 km × 20 days × 12 months = 6,000 km/year

6,000 km × 0.16272 kgCO₂e/km = 976.32 kgCO₂e/year

Now scale it up. A 40-person organization runs the commute survey and finds twelve staff drive to work: eight petrol drivers averaging 6,000 km/year each (48,000 km total), two diesel drivers averaging 8,000 km/year each (16,000 km total), one hybrid driver at 5,000 km/year, and one driver whose fuel type wasn't captured, estimated at 7,000 km/year.

Petrol: 48,000 km × 0.16272 = 7,810.56 kgCO₂e

Diesel: 16,000 km × 0.17304 = 2,768.64 kgCO₂e

Hybrid: 5,000 km × 0.12825 = 641.25 kgCO₂e

Unknown: 7,000 km × 0.16725 = 1,170.75 kgCO₂e

Total = 12,391.2 kgCO₂e ≈ 12.4 tCO₂e for the year

For a 40-person organization, that lands in a similar order of magnitude to the annual Scope 2 electricity footprint of a comparable office (see the business electricity calculator). Commuting is rarely the single biggest Scope 3 line, but it is frequently bigger than people expect, and — unlike many spend-based Scope 3 estimates — it can be built from a survey employees can actually answer accurately.

What this calculator doesn't cover

The distance-based method is honest about what it counts, so be honest about what it leaves out:

  • Bus, rail, and motorcycle commutes. We don't currently have an open-licensed factor in our registry for these modes, so they're excluded rather than estimated with an unsourced number. Note the gap in your methodology; for most organizations the car-driving share still dominates the category, but a workforce with a large public-transport share will be undercounted here.
  • Electric vehicles. An EV commute has no combustion factor — its emissions come from grid electricity used for charging. If a staff member can estimate the kWh, route that through an electricity calculation using the region where charging happens, not this tool.
  • Taxis and ride-hailing. A ride to the office is still commuting, but it doesn't fit the average-car factors above, which assume a personally driven vehicle. Distance-based estimation is possible with a different factor set; it's out of scope here.
  • Company-owned or company-fuelled vehicles. If the organization owns the car or pays for the fuel card, those kilometres are Scope 1 — put them through the fleet fuel calculator instead, and don't double-count them here.
  • Carpooling and occupancy. The average-car factors assume one driver per vehicle. If several staff genuinely share a single car for the whole commute, applying the factor once (not once per passenger) avoids overstating the total.
  • Homeworking. Days worked from home avoid the commute but add home energy use — a separate category 7 consideration this tool doesn't model.
  • Survey error. Self-reported distances and working-day counts are estimates. Keep survey responses on file as evidence, rerun the survey annually or when headcount shifts, and flag the figure as survey-based in any disclosure.

Where this fits in your reporting

Employee commuting is Scope 3, category 7 on every framework — the category applies identically whether the organization surveying its staff is a company, a nonprofit, a school, or a public agency. Whatever the number eventually feeds — ISSB IFRS S2, GRI 305, CDP, or a national reporting code — the arithmetic here (annual km × average-car factor, summed by fuel type) is the same distance-based method the GHG Protocol recommends when individual fuel-consumption data isn't available. It is also one of the cheaper Scope 3 categories to stand up: one survey, four km totals, done. Singapore-listed readers can check exact filing dates in our SGX climate reporting deadlines guide.

When the survey comes back as a spreadsheet, upload the file directly — the free tier takes 3 documents a day anonymously (10 with an email address), files are auto-deleted after 30 days, and every extracted figure carries the same factor provenance as a manual calculation.

Sources

Frequently asked questions

Is employee commuting Scope 1, 2 or 3?
Scope 3, category 7 — indirect emissions from employees travelling between home and work in vehicles the organization does not own or control. Fuel burned in company-owned vehicles is Scope 1 and belongs in a fleet fuel calculation instead.
How do I turn a staff survey into annual kilometres?
Ask each driver for their round-trip commute distance in km and their working days per year (a typical full-time pattern is about 20 days a month, 240 a year). Annual km = round-trip km x working days. Sum the drivers by car fuel type — petrol, diesel, hybrid, or unknown — and enter the four totals above.
What if I don't know a driver's fuel type?
Use the 'car, fuel type unknown' field. Its factor is a fleet-average figure across petrol, diesel and hybrid cars, so it is a reasonable default when a survey response is incomplete or when you are estimating from headcount rather than individual responses.
What about staff who commute by bus, rail, or motorcycle?
Not covered yet. We only publish a factor once we can trace it to an open-licensed source, and we don't currently have one in our registry for bus, rail, or motorcycle passenger travel. State the gap in your methodology notes — for most organizations, car-driving staff still dominate this category, but a commute survey that includes public-transport users will undercount them here.
Do electric vehicles count as commuting emissions?
Yes, but not through this tool — an EV commute burns no fuel and has no combustion factor. Its emissions come from the grid electricity used for charging, so route the estimated kWh through an electricity calculation instead, using the region where the charging happens.