This Portfolio Carbon Calculator is a free tool to estimate a portfolio's carbon footprint.

Enter information for a portfolio below and we'll calculate its carbon footprint, in both absolute metric tons and the equivalent number of cars added to or removed from the road.

Data is based on company-reported scope 1 and 2 carbon emissions. We calculate emissions for a portfolio based on the portfolio's holdings and overall value. For more details see the methodology section below.

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cars removed from the road by your portfolio

1. Set portfolio value
2. Add holdings
3. Set holding weights
Holding Carbon footprint Weight


1. Calculate carbon emissions from portfolio holdings

We first estimate the weighted-average carbon emissions of a portfolio's holdings, measured in metric tons.

Emissions for each company (stock) held by the portfolio are based on company-reported scope 1 and scope 2 emissions, net of offsetting products (such as solar or wind energy produced).

Emissions for each fund held by the portfolio are based on the fund's composition, i.e., a weighted-average of emissions for each company in the fund.

Some companies and funds have negative carbon emissions, meaning their products reduce or remove global carbon emissions (such as wind or solar power).

2. Compare to an average portfolio

We compare the portfolio's weighted-average carbon emissions to an "average portfolio", which we calculate using a broad basket of widely-traded ETFs and mutual funds. The basket includes both sustainable (or ESG) funds as well as non-sustainable funds.

Based on the portfolio's carbon emissions relative to an average portfolio, we assign a carbon efficiency score to the portfolio (i.e., portfolio holdings produce X% more or less carbon emissions than average).

3. Calculate equivalent cars taken off or added to the road

To get the estimated cars taken off or added to the road by a portfolio, we divide the portfolio's total value by the average annual cost of owning a car in the US ( ~$9,300 based on data from AAA) and multiply by the portfolio's carbon efficiency score.

For example, if a portfolio's value is $20,000 and the portfolio is 50% more carbon efficient than average, the portfolio would remove approximately 1.1 cars from the road ($20,000 / $9300 * 50%).