How we calculate

Money saved

Formula: quantity × new price − price paid − transport price

The new price is the original new price given in the listing. Without one we start from the category's default price, stored in euros, convert it to the listing's currency and mark the figure "estimated".

The answer to "Would you otherwise buy new?" does not change the money.

Example: MacBook Air M1, 10 pcs, free, new price RSD 135,000 each. Saving: 10 × RSD 135,000 = RSD 1,350,000 ≈ €11,519.55.

CO2e saved

Formula: quantity × production emissions × substitution × life factor × (1 − refurbished share) − transport

Production emissions

The emissions of producing one new item, in kg CO2e, from the category's factor in force. The sources are listed below.

Substitution

The claimant's answer to "Would you otherwise buy new?": yes 1 · unsure 0.7 · no 0.3. Before there is an answer, for example in the listing preview: 0.8.

Life factor

The share of the lifetime left since the month of purchase, at least 0.5. Without a purchase date 0.5.

Refurbished share

When the factor's source says part of the product is refurbished, that part is taken off.

Transport

The straight-line distance between the pickup place and the receiver's address × the vehicle's factor: diesel van 0.252 kg/km, electric van 0.02 kg/km, truck 0.44 kg per tonne-kilometre.

Range

The low end uses the factor's low value and a substitution of at most 0.7, the high end its high value and 1. Transport is taken off both.

The gross figure is quantity × production emissions; the net figure is the formula above, and the indicators show it. When transport outweighs the saving, the net figure can be negative.

The factors cover the production of a new product (A1–A3: raw materials, transport to the factory, manufacturing); use and end of life are not included.

For a category without a product footprint (speakers, whiteboard, custom items) the factor is mass × material factor (ICE) × 1.2.

The saving counts for the receiver, so no exchange counts twice; the giver sees how much it made possible.

Example: MacBook Air M1, emissions 160 / 185 / 210 kg. The listing preview per item: 185 × 0.8 × 0.5 = 74 kg, range 56 kg–105 kg. For the completed exchange of 10 items: 924.75 kg.

Items reused

The number of items handed over in completed exchanges. It counts for the receiver.

Mass kept from waste

Formula: quantity × the category's mass

Example: 10 × 1.29 kg = 12.9 kg.

Completed exchanges

An exchange is completed when both sides have confirmed the handover. The figures are recorded then, and the exchange does not change anymore.

Currencies and exchange rates

A listing is in the currency of the organization's country: dinar, forint or euro. The totals are in euros, at the reference rate of the month of completion. The rate is stored when the exchange is completed.

What does it compare to?

We compare the CO2e saved with familiar amounts:

• driving: 0.15 kg CO2e per kilometre.