Customer Story

Sierra Club turns one-time donors into monthly donors to drive revenue with Optimizely


Increase in online donations since 2015


Initial tests led to over 200K


Founded in 1892, the Sierra Club was one of the first environmental organizations in the United States. Today, they’ve got over 3.5 million members and supporters and a staff of 600 on a mission to improve the environment.

Products Used

It's your turn. How will you experiment everywhere?


Sierra Club partnered with CROmetrics and Optimizely to improve donor acquisition. At first, they used a team of 3, the “advancement department,” to organize tests around home page design and donation forms.

Today, an internal team of 9 works with Optimizely to test Sierra Club’s growing online donations and email signups. After seeing dramatic improvement with their initial web and form tests, to the tune of 2 million dollars —they’re running more complex tests like actions around advocacy, petition signups, and even encouraging members to write letters to Congress.

Initial tests are worth over $200,000

Sierra Club’s online donations have increased by a whopping 830% since 2015. Improving their online conversions has been a major goal for the digital team.

In one initial test, Sierra Club added a “cover credit card processing fee” checkbox to their donation form.

Most donors checked the box to cover the processing fee, which added 3% to most gifts, totaling about $175,000 over the year.

In another test, Sierra Club decided to test the forms connected to their Facebook Ads since they were making significant investments in advertising on Facebook. They tested a 2-step email signup form in their ads. Just one test of a simpler email capture was worth $200,000.

We ran a test...a 2 step email increased conversions 20%. This one test was worth $200,000…Drew Seman

Turning one-time donors into monthly donors

Many nonprofits raise most of their revenue in the last month or so of the year—and Sierra Club is no exception. But Sierra Club recognized the value in monthly donors early on. Monthly donations are repeatable income and they increase the overall amount that they are raising. Sierra Club’s ability to move donors from one-time donor to monthly donor has increased year-round revenue.

In one initial experiment, they tested a form that was triggered after a user action. The first version of the form asked users for a one-time donation, the test version asked users for a monthly donation.

Top: One of several 1x forms, Bottom: Monthly form

Switching the form from the default to asking for monthly donations improved long-term backend revenue from about $200,000 to $1 million dollars in the last 2 years.

Increasing monthly donors with arrows and clear CTAs

Sierra Club’s data showed that the long-term value of a monthly donations was 5x, a one-time donation. Since monthly donations were worth so much more, it was apparent to Sierra Club that they should encourage monthly donations over one-time donations.

One of the biggest impacts that Sierra Club saw with experimentation was an increase in monthly donations when they used an arrow to ask users to turn their one-time donations into a monthly donation.

Here is our original arrow test (no arrow vs arrow).

Additionally, the Sierra Club has continued to iterate on this test and actually discovered that “social proof” messaging (e.g. 93,000 donors have signed up) works even better.

Higher donations through decreased form fields

Another experiment that had a massive impact for Sierra Club was removing distractions from their donation form. They simplified the form fields and saw a 14% increase in monthly donations and a $42k projected annual increase in monthly donation revenue.

  • 14% increase in monthly donations
  • 8% increase in click-through rate from step 1 to step 2
  • 3% increase in click-through rate from step 3 to step 4
  • $42k increase in projected annual donations

Elevating relevant content elevates click-through

Positioning can make or break click-through rates. Sierra Club used experimentation to improve click-through by moving the most relevant content to the space above content about the organization. This one move drove a 36% increase in clicks on their “Happening Now” section for web visitors and a 29% increase in monthly donations.

  • 36% increase in clicks to “Happening Now”
  • 29% increase in monthly donations
  • 5% increase in one-time gifts
  • $74k increase in projected annual donations
Variation (right) swapped 'We' content with 'Happening Now' content

Getting the most value out of experimentation

Sierra Club sees the most powerful returns where they have clear, defined KPIs and customer data. For example, knowing that the average lifetime value of a digitally acquired monthly donation is $500, helps them prove value with experimentation. Not only has this proven value helped get other departments involved in experimentation, but it’s proven significant ROI to directors and board members, and they plan to continue growing their experimentation program.