Programmatic ad exchange Sharethrough has launched a free tool that approximates the amount of carbon produced by a digital campaign.

Using the Carbon Emissions Estimator, advertisers can input details about a potential campaign, such as number of impressions, type of creative and type of inventory, and the tool will calculate the estimated number of metric tons of carbon that the campaign will generate.

Many factors can affect a campaign’s carbon footprint, including the specific publisher inventory that is targeted, the effectiveness of the supply path, and the creative. The Carbon Emissions Estimator allows advertisers understand the environmental impact of their campaigns.

“Digital advertising is often thought of as a more environmentally conscious alternative to print ads or mailers, because there’s no physical waste,” says JF Cote, CEO of Sharethrough. “However, the fact of the matter is that digital ads have an impact on the environment as well, even if we can’t see it.”

Cote says the estimator is an addition to a toolkit the company has been developing to help the industry reduce its carbon footprint, including developing GreenPMPs, private marketplaces that measure and report on a campaign’s carbon footprint, then offset it by participating in one of Scope3’s carbon removal projects.

Sharethrough’s carbon estimations are based on averages from hundreds of millions of impressions delivered via GreenPMPs, which have found that one million ad impressions create roughly one metric ton of carbon dioxide equivalent, which is equal to a round trip flight from London to Boston for a single passenger.

The carbon footprint of advertising has been put into sharper focus over the last year as the industry has become more aware of the impact it has on the environment, especially when it comes to automated and programmatic ad systems that require great deals of energy to provide computational power. Last year, GroupM released a report calling the industry’s attempts to reduce its carbon footprint “insufficient,” thanks to relying on carbon calculators that use incomplete data that doesn’t capture the entirety of the supply chain, getting info from questionable sources and focusing on “offsetting” emissions instead of reducing them.