What it means
Food miles are the distance food travels from production toward consumption, and a local and an imported product can travel very different distances across a farm, packing plant, port, warehouse and store. State which legs are included before quoting miles or kilometres.
The USDA agricultural thesaurus defines food miles as a distance concept, while Our World in Data explains why food emissions also depend on production and transport mode, so a longer route does not always mean a larger total footprint. A simple measure adds the distance of each shipment leg, though for multi-ingredient food the weighting matters.
A fictional bakery that uses local flour and imported chocolate cannot call the whole cake "50 food miles" just because the bakery is nearby, since that hides the chocolate route. Some analysts use tonne-kilometres, shipment mass multiplied by distance, so 2 tonnes of produce moved 100 kilometres is 200 tonne-kilometres, though emissions still require an appropriate factor for the transport method.
Comparing distance alone misses large differences between modes. A fictional orchard sending apples 200 kilometres to a local market and a supplier flying berries 2,000 kilometres are not comparable on distance, because air freight is typically emissions-intensive per unit carried compared with sea transport, and vehicles, fuel, load and refrigeration all affect the result.
A fictional grocer receiving vegetables by road from nearby farms and grains by ship from abroad therefore studies each supply chain, using actual mode and route rather than an assumed straight-line distance. Production can dominate a food's footprint, since land use, livestock methane, fertiliser, energy and farming method all matter.
A locally grown tomato from a heated greenhouse can differ sharply from a field-grown import, and Our World in Data reviews life-cycle impacts and cautions against reducing every choice to transport. This is not a universal argument to buy imported food, but a fictional buyer comparing two winter tomatoes should request production and transport data before making a climate claim.
Storage, processing, packaging and waste also affect impact, and a food that spoils before sale creates losses beyond its transport, so the most useful comparison uses a consistent unit such as emissions per kilogram of edible food. A fictional retailer that switches to a closer supplier but suffers more spoilage from delivery gaps must check total impact and service quality.
For business logistics, food miles can still reveal risk and cost, since long routes may need more lead time, inventory and coordination, although freight price depends on mode, volumes, contracts and fuel, not distance alone. Avoid vague "zero food miles" claims, because even a farm shop has inputs and customers travelling to it.
A fictional cafe growing herbs on its roof can say they are grown on site, but not that a herb dish has no transport footprint when other ingredients arrive from elsewhere. If a carbon estimate is needed, use mode-specific factors and a stated life-cycle boundary rather than one universal emissions number, and treat food miles as one measure alongside seasonal sourcing, waste, quality, cost and labour practices.
In practice
Real-world examples.
Example
A buyer for a fictional supermarket sums the farm-to-packer and packer-to-store route distances for a salad crop. She records 500 kilometres in total and lists each leg, so a supplier cannot be compared with another on a different boundary.
Example
A distributor measures tonne-kilometres for a road freight leg carrying 2 tonnes over 100 kilometres, giving 200. The operations team uses the figure to compare the leg with a rail alternative, then asks for vehicle and fuel data before comparing emissions.
Example
A grocer compares transport modes for two berry suppliers before making an emissions claim in its marketing. It finds that the shorter route is by air while the longer one is by sea, and it drops the distance claim altogether.
Formula
Calculation
Food miles for one route = sum of included transport-leg distances. Freight work in tonne-kilometres = tonnes carried x kilometres for each leg, then summed.
Worked example. A fictional distributor moves 2 tonnes of produce in three legs: 80 kilometres from farm to packer, 120 kilometres from packer to port and 300 kilometres from port to store.
- Route distance = 80 + 120 + 300 = 500 kilometres.
- Tonne-kilometres = (2 x 80) + (2 x 120) + (2 x 300) = 160 + 240 + 600 = 1,000.
- Emissions would then need a mode-specific factor for each leg; the distance and tonne-kilometres alone do not state them.Case study
Seen in the real world.
In this fictional case, Bay Market compares a local greenhouse tomato with a field-grown imported tomato. The local route is shorter, but heating may change total emissions. The buyer records route and transport mode, asks for production data and avoids declaring a winner from distance alone. The market's sustainability lead then adds a short sourcing note to its product pages that states the route boundary, the distance unit and the transport mode for each line. Staff are told not to use phrases such as "zero food miles" unless the product is genuinely harvested on site, and the note is reviewed when suppliers change.
Watch out
Common mistakes.
- Treating distance as a complete carbon-footprint measure.
- Ignoring intermediate legs or imported ingredients.
- Applying one emissions factor to air, road and sea freight.
Questions
People also ask.
Do fewer food miles always mean lower emissions?
No. Production methods, transport mode and waste can change the result.
What is a tonne-kilometre?
One tonne moved one kilometre, a measure of freight work rather than emissions.
What should a food-miles claim specify?
The route boundary, distance unit, product and ideally transport mode.
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