Where a product's emissions actually come from

Ask someone where the carbon in a purchase comes from and most people say the same thing: getting it to me. It is a reasonable guess. For most products it is also wrong, and the gap between the guess and the data is large enough to change which product you should buy.

The intuition, and why it misleads

Transport is the part of a supply chain people can see. You watch the van arrive. You do not watch the ore get smelted, the polymer get cracked, the wafer get etched, or the greenhouse get heated through a winter. So the visible step feels like the important one.

But by the time a product reaches a delivery van, almost all of its emissions have already happened — in mining, refining, chemical processing, component manufacture, assembly, and the electricity that powered each of those stages. Shipping a finished object is, energetically, a small job compared with creating it.

What the published data shows

Manufacturers that publish product carbon footprints break the total down by life-cycle stage. Two examples, both from the manufacturers' own reports:

In both cases transport is roughly one-tenth of the footprint, and making the device is roughly three-quarters of it. Buying a laptop that was manufactured with less carbon matters several times more than how it reached you.

This pattern is not universal. Air-freighted fresh produce, heavy low-value goods, and anything refrigerated in transit shift the balance toward distribution. But for most manufactured items in most supply chains, production dominates.

Why the calculator is built the way it is

Because production dominates, the estimate shown by this calculator covers the production supply chain — everything upstream that went into making the item — and not delivery to you. That is a deliberate scope choice, and the per-item breakdown says so on every result.

It also explains a result that surprises people. Search for a Mother's Day gift and compare a fresh flower arrangement with an artificial one at a similar price. The fresh flowers carry roughly four times the emission intensity per yen, because cut flowers are grown in heated greenhouses, kept refrigerated, and often flown. None of that is visible at the point of sale — but it is most of the footprint, and once a carbon price is applied it can flip which gift is cheaper.

What this means when you shop

• The category matters more than the courier. Choosing a less carbon-intensive kind of product usually beats optimising delivery.
• Consolidating orders helps a little; buying less helps a lot. If production is three-quarters of the footprint, the largest lever is whether an item is made at all.
• Longevity is a carbon strategy. When most emissions are incurred at manufacture, a product that lasts twice as long roughly halves its annualised footprint — which is why a durable item can beat a "greener" disposable one.
• Beware of price as a proxy. A cheaper item is not automatically lower-carbon; it is often the opposite, if the price is low because the product is short-lived.

An honest caveat

The figures this calculator shows are category averages scaled by price, not measurements of the specific product. They are good enough to compare a category against another category, and not good enough to compare two items within the same category. The methodology page sets out exactly how they are derived and where they break down.