Food Miles Calculator

Enter the weight of food in pounds. The calculator divides by 2,204.62 to get tonnes, so 10 lb is 0.0045 tonnes. Use the shipped weight, including anything like a crate or ice that travels with it, if you know it.

Enter the distance in miles: the main freight leg, such as farm or port to a regional distribution centre. The calculator multiplies by 1.60934, so 1,600 miles is 2,575 km.

Choose the transport mode. With truck, the result is 1,285 g of CO2, shown as 2.83 lb (1.28 kg).

Switch the mode without changing anything else to see the spread on the same trip: rail gives 0.90 lb, sea 0.51 lb, and air 29.10 lb. The chart on the page draws this comparison for your inputs, and it is usually more useful than the single number, because in practice the choice is rarely between distances and often between modes.

Weight (tonnes) = pounds ÷ 2,204.62.

Distance (km) = miles × 1.60934.

Emissions (grams) = weight in tonnes × distance in km × mode factor. Emissions (lb) = grams ÷ 1,000 × 2.20462.

Mode factors (g CO2e per tonne-km): sea 20, rail 35, truck 110, air 1,130. A tonne-kilometre is one tonne moved one kilometre, which is why the factor can be applied to any combination of weight and distance.

Where the factors come from. Poore and Nemecek's 2018 *Science* study applied freight factors from the ecoinvent lifecycle database. Our World in Data's summaries of that work give 1.13 kg per tonne-km for air freight (the calculator's 1,130 g) and about 10 to 23 g for sea freight, consistent with the calculator's 20. The same summaries give roughly 50-60 g for rail and around 200 g for road, both above the calculator's 35 and 110, so this tool's rail and truck results are on the low side of that dataset. We could not trace those two values to a single named source, and they should be read as conservative.

Now fly the same 10 lb of produce 5,500 miles, the kind of route used for fresh berries, asparagus or cut flowers out of season. Distance becomes 8,851 km, and at 1,130 g per tonne-km the result is 45,369 g, or 100.02 lb of CO2.

Ship it the same 5,500 miles by sea instead and the result is 1.77 lb. Air is 56.5 times the sea figure on an identical trip, because the factor is.

The comparison with the first example is the instructive one. The trucked produce travelled 1,600 miles and emitted 2.83 lb; the sea-freighted produce travelled more than three times as far and emitted 1.77 lb. The air-freighted produce emitted about 35 times as much as the trucked produce while travelling about 3.4 times as far.

This is why air freight is the exception that makes food miles matter. Our World in Data reports that only about 0.16 percent of food miles are travelled by air, yet because each of those miles carries a factor so much larger than every other mode, air-freighted foods are the ones where transport becomes a large share of the footprint.

Take 1 kg of beef shipped 9,000 km by sea. This calculator gives 180 g of CO2e for the voyage. Our World in Data, from Poore and Nemecek's data, puts the average footprint of beef from dedicated beef herds at about 60 kg of CO2e per kilogram, almost all of it from land use, feed and the methane cattle produce. The long sea journey is about 0.3 percent of the total.

Even flying that kilogram 9,000 km, at 10,170 g, would add less than a fifth to beef's footprint. By contrast, for a low-footprint plant food flown the same distance, the flight could easily be most of the total.

The practical rule that follows: what you eat moves your food footprint far more than where it came from, with one clear exception: avoid highly perishable foods that arrive by air. Out-of-season, fragile and short-shelf-life items are the likeliest to have flown. Shelf-stable and long-lasting foods almost always travel by sea, rail or road.

Local food can also carry a higher footprint when it is grown in heated greenhouses out of season. This calculator can't see that, because it measures only the freight leg.

This is transport only. Farming, fertiliser, land-use change, processing, packaging, retail refrigeration, cooking and waste are all outside it, and for most foods those dominate.

It covers one freight leg with one mode. Real supply chains combine modes (a truck to port, a ship, a truck to a warehouse, a van to a store) and the last mile to your home, often by car, can outweigh a long efficient leg for a small basket. Refrigerated transport uses more energy than ambient freight, which the single factors here do not distinguish.

The factors are averages. Load factor, vessel size, aircraft type (bellyhold on passenger flights versus dedicated freighters), and truck efficiency all change the real number, and the rail and truck factors used here are lower than the dataset behind the air factor.

For the production side of a food's footprint, which usually matters more than transport, see the meat vs. plant-based diet carbon calculator. For a broader personal footprint picture, use the carbon footprint calculator, and the food waste impact calculator estimates the emissions of food that's shipped but never eaten, every stage of its footprint wasted at once.

The same mode-over-distance conclusion applies to parcels. The Shipping & Package Carbon Footprint Calculator prices line haul, last mile and packaging on chargeable weight, and shows air freight running roughly eight times worse than ground for an identical box.