Grams CO2 Per Km To Grams CO2 Per Mile Converter
Convert vehicle emissions between g CO2/km and g CO2/mile, with annual mileage and tailpipe total estimates shown separately.
Convert Vehicle CO2 Rate
Converted CO2 Rate
120 g CO2/km converts to 193 g CO2/mile.
Quick Answer
To convert grams CO2 per kilometre to grams CO2 per mile, multiply by 1.609344. A car listed at 120 g CO2/km is therefore about 193 g CO2/mile. To convert the other way, divide g CO2/mile by 1.609344. The conversion only changes the distance unit. It does not alter the vehicle’s test method, official rating, real-world fuel use, electricity source, payload, driving style or weather. Use the result when a UK or European g/km figure needs to be compared with a mile-based report, fleet spreadsheet or US-style emissions note.
Formula And Annual Estimate
g CO2/mile = g CO2/km x 1.609344
g CO2/km = g CO2/mile / 1.609344
Annual kg CO2 = g CO2/mile x annual miles / 1000
Annual kg CO2 = g CO2/km x annual km / 1000
Annual tonnes CO2 = annual kg CO2 / 1000
The mile-to-kilometre factor is exact for this purpose. Annual emissions are shown in kilograms because multiplying grams by thousands of miles quickly gives a large number. If your source is a manufacturer or DVLA CO2 figure, it may be a regulated test result. If your source is a fleet fuel report, it may be an operational estimate. Keep the source name beside the converted value so the meaning is not lost.
g/km To g/mile Conversion Table
| g CO2/km | g CO2/mile | Annual At 8,000 Miles | Comment |
|---|---|---|---|
| 50 | 80 | 644 kg | Low test value or plug-in hybrid context. |
| 75 | 121 | 966 kg | Low conventional rating. |
| 95 | 153 | 1,223 kg | Common reference style value. |
| 100 | 161 | 1,287 kg | Round benchmark. |
| 120 | 193 | 1,545 kg | Default example. |
| 150 | 241 | 1,931 kg | Medium to higher car rating. |
| 180 | 290 | 2,317 kg | High-emission car rating. |
| 200 | 322 | 2,575 kg | Large vehicle comparison. |
| 250 | 402 | 3,219 kg | Very high tailpipe rate. |
| 300 | 483 | 3,862 kg | Heavy or performance context. |
Official Rating Versus Real Driving
Vehicle CO2 figures are often reported as grams per kilometre because UK and European vehicle testing and taxation have used km-based values. A driver or fleet manager may prefer mile-based values because mileage logs, leases, insurance records and service plans often use miles. Converting g/km to g/mile helps align those records, but it does not make the official test value a real-world fuel result. Speed, tyre pressure, load, roof boxes, cold starts, traffic, hills and driving style can all move actual emissions.
For electric vehicles, a tailpipe g/km value may be zero, but whole-life and electricity-generation emissions require a different method. Do not use a tailpipe conversion to compare full carbon footprints unless the source clearly states the same boundary. For fleet reporting, record whether the value is tailpipe only, fuel-cycle, electricity use, or a government conversion-factor estimate.
When a spreadsheet combines several cars, keep three columns: original value, original unit and converted value. That prevents a g/mile figure from being mistaken for g/km later. If one vehicle comes from an older NEDC record and another from WLTP data, do not treat the converted numbers as fully comparable without noting the test method. The unit conversion is exact; the source boundary may not match. Add the source document name and year.
Mileage Record Tips
Annual totals are only as good as the distance entered. Company cars, pool vehicles and delivery vans may have mixed business and private mileage, so decide which mileage is in scope before calculating annual kg CO2. For a personal comparison, use odometer records or service history rather than a rough memory. For fleet reporting, keep the calculation year, mileage source and vehicle registration record together. If fuel cards or telematics provide actual fuel use, that may be a better carbon source than a brochure g/km figure.
Worked Examples
| Task | Calculation | Result | Record Note |
|---|---|---|---|
| 120 g/km to g/mile | 120 x 1.609344 | 193 g/mile | Round to whole grams for a fleet sheet. |
| 200 g/mile to g/km | 200 / 1.609344 | 124 g/km | Useful when reading mile-based sources. |
| 95 g/km at 8,000 miles | 95 x 1.609344 x 8,000 / 1000 | 1,223 kg CO2 | Tailpipe estimate only. |
| 0 g/km EV tailpipe | 0 x 1.609344 | 0 g/mile tailpipe | Electricity emissions need another method. |
FAQs
How do I convert g CO2/km to g CO2/mile?
Multiply the g/km value by 1.609344. For example, 120 g/km multiplied by 1.609344 equals about 193 g/mile.
How do I convert g CO2/mile to g CO2/km?
Divide the g/mile value by 1.609344. For example, 200 g/mile divided by 1.609344 equals about 124 g/km.
Does the conversion change the official car rating?
No. It changes the distance unit only. The original test method and rating source remain the same.
Can I use this for vehicle tax?
Use official DVLA or GOV.UK vehicle tax sources for tax decisions. This converter only translates g/km and g/mile.
Does this include fuel production or electricity generation?
No unless your original source already included those boundaries. The default calculation is a rate conversion and tailpipe-style annual estimate.
Why show annual kg CO2?
Annual kg CO2 helps turn a per-distance rate into a planning number for mileage records, fleet reports and car comparisons.
Sources
- National Institute of Standards and Technology. (2008). Guide for the Use of the International System of Units. NIST Special Publication 811. https://www.nist.gov/pml/special-publication-811
- Department for Environment, Food and Rural Affairs. (2025). Greenhouse gas reporting: conversion factors 2025. GOV.UK. https://www.gov.uk/government/collections/government-conversion-factors-for-company-reporting
- Driver and Vehicle Licensing Agency. (n.d.). Vehicle tax rates. GOV.UK. https://www.gov.uk/vehicle-tax-rate-tables