Wren Review: A Subscription To Offset Your Carbon Footprint

Wren helps you calculate and offset your personal carbon emissions through a monthly subscription. Learn if it’s worth the cost.

SustainFi September 10, 2021

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  • Wren lets you buy carbon offsets to compensate for your carbon emissions
  • Offsets are offered on a subscription basis
  • The average subscriber pays $23 per month


  • Wren’s calculator helps you estimate carbon emissions to offset
  • The platform is easy to use and Wren provides plenty of educational material
  • Wren makes sure the projects are measurable and wouldn’t have taken place without your money


  • Wren’s offsets are more expensive than offsets from Terrapass or Cool Effect
  • Offsets, but doesn’t eliminate, your carbon footprint
  • May encourage some people not to reduce their carbon footprint

What is Wren? 

Also known as Project Wren, Wren is a startup that sells individual carbon offsets. The basic idea behind carbon offsets is to balance your carbon emissions by removing the same amount of CO2 from the atmosphere. Removal can be done by planting trees, which capture carbon, or in other ways.

Wren’s calculator lets you determine what your emissions are and then buy a subscription to offset them. It takes into account where you live, what car you drive and how you get around, how often you eat meat, how often you fly, and much more. Based on your score, Wren suggests how much you need to offset.

An average Wren user pays $23 a month to offset their carbon footprint, and one ton of carbon offsets costs $18 (as of September 2021.)

Based in California, Wren was founded in 2019 by three University of Southern California graduates in their early 20s who wanted to make an impact. Wren is a Public Benefit Corporation backed by Y Combinator, a well-known startup incubator. (A Public Benefit Corporation is a for-profit business that pledges to balance mission and profits.)

How do carbon offsets work?

Most of your everyday activities like heating or cooling your home, driving a car, eating meat, and even shopping online, create polluting emissions. Emissions of greenhouse gases like carbon and methane are the primary cause of global warming. According to several estimates, an average American emits between 16 and 20 tons of carbon every year.

So what can you do?

You can reduce your emissions by driving less, flying less, or buying an electric car, but you can’t get rid of them completely. So, companies like Wren, Cool Effect and Terrapass let you buy carbon offsets to cancel out your emissions.

Carbon offsets come from projects that remove CO2 from the atmosphere. For example, these projects can preserve or plant forests or capture methane from landfills. Although the quality of CO2-capturing projects varies, and offsets are not without critics, buying offsets is better than doing nothing.

Wren acknowledges that offsets are not enough to solve climate change, and their site suggests resources for other steps you can take.

In today’s market, offsetting one ton of individual emissions costs anything between $10 and $30 per ton. So, if you generate 20 tons of emissions each year, you will pay between $200 and $600 annually for offsets.

There are many online calculators to estimate your carbon footprint. Some will also help you find ways to cut your emissions, so you don’t have to offset as much.

What projects does Wren support?

Wren seeks to support carbon removal projects that are measurable, have a lasting impact, and wouldn’t happen without your money. Where applicable, they monitor projects using satellite imagery and GPS.

The carbon-removing projects Wren supports include:

  • Planting trees. Planting trees helps sequester carbon, in addition to improving air quality and promoting biodiversity. Wren supports a tree-planting project in Kenya where farmers are paid to grow trees.
  • Clean-burning cookstoves. Traditional wooden cookstoves used in many developing countries emit a lot of carbon. Replacing them with cleaner-burning cookstoves makes a big difference. Wren is supporting a project in Uganda that provides clean-burning fuel and cookstoves to refugees.
  • Biochar production. Dead trees can be removed (which helps prevent wildfires) and converted into biochar to keep carbon out of the air.
  • Rainforest protection. Wren supports a rainforest protection project in Peru, where satellite monitoring and drones can detect illegal logging and deforestation early.
  • Regenerative agroforestry. Regenerative agroforestry projects buy degraded land to replant it and recycle forest waste into biochar. 

Wren carbon footprint calculator

Wren offers a comprehensive carbon calculator you can check out here. It is the most user-friendly calculator we have seen. The calculator uses data from the World Bank and the UC Berkeley’s Cool Climate Network.

The calculator takes into account:

  • Where you live
  • The car you drive (if you drive) and how you get around
  • How much and where you fly
  • What you eat
  • How big your apartment is
  • How much you spend on furniture, appliances, clothes, services and other “stuff”
  • How much electricity and natural gas you use and if you use renewable energy

According to Wren, an average American emits 19.5 tons of carbon each year. This compares to the U.K. average of 8.9 tons and the India average of 2.2 tons. You can compare your emissions to U.S. and global averages.

How much do Wren’s carbon offsets cost?

Wren currently charges $18 per ton of carbon. While it is not the cheapest, the subscription model and the site are informative and easy to use.

If your emissions are in line with the average American, you will pay $351 annually or $29.25 per month. (The average Wren user pays $23 per month.)

You can also do more than just offset your emissions, becoming climate-positive instead.

🔔 Looking to compare offset prices? See how the top ten carbon offset providers compare.

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How does Wren make money?

For each $1 you give to Wren, 80 cents go to fund carbon projects, 3 cents go to the payments provider Stripe to process the transaction, and the remaining 17 cents support Wren’s business, enabling them to hire talent and eventually make a profit.

Who owns Wren?

Wren is a venture capital-funded startup. Its investors include Union Square Ventures and Y Combinator co-founder Paul Graham.

Alternatives to Wren

There are hundreds of companies that sell carbon offsets. You can compare prices for the best-known ones here. Wren is not the cheapest, but it’s very convenient and easy to use. It also provides more educational materials than its competitors and lets you compare your emissions to others. Notable competitors include:

Cool Effect

Cool Effect is a carbon offset nonprofit that started by installing clean-burning cookstoves in Honduras in 1998 but now specializes in travel offsets. Roughly 90% of the price you pay for offsets goes to carbon-reducing projects. They are the cheapest carbon offset company we’ve found, charging $9.9 per ton without a subscription.

🔔 Read the review here.


Terrapass sells carbon offset subscriptions based on how much carbon you emit each month from home energy use, driving, flying, and household waste. There are separate offset packages for flights and certificates to support renewable energy. Terrapass also has a handy calculator to determine your individual carbon footprint. They currently charge roughly $11 per ton ($9.9 with a subscription.)

🔔 Read our review of Terrapass here.


Swiss company Climeworks runs the first commercial direct air capture facility. Their plant sucks CO2 directly from the atmosphere. While their offsets are expensive, they are certain and measurable.

🔔 Read our review of Climeworks here.

🔔 Did you know that you can also invest in voluntary carbon offsets? Learn how.