You may have added a fundraising thermometer to your campaigns because it seemed like the 'right' thing to do — and it is. It's an easy way for you (and your supporters) to watch a goal come together in real time.
But have you noticed that donations tend to pick up speed as your campaign approaches its target? Why does that happen? It isn’t timing or luck. It’s behavioral science.
That humble thermometer — the one that seemed like little more than a nice-to-have visual aid — is doing a surprising amount of psychological work on your donors every time they land on your campaign page. Here’s what’s actually going on, and how you can use it to your advantage.
3 reasons fundraising thermometers work (according to behavioral science)
The short answer is that a well-placed thermometer taps into several well-documented quirks of human psychology — all at the same time. Here’s a closer look at the three biggest ones.
1. They make donors feel like the deciding factor
The closer a donor gets to seeing a campaign reach its goal, the more likely they are to give — and to give more. This is the goal gradient effect, first observed in rats running mazes and later confirmed across a wide range of human behavior. It’s even been observed directly in charitable giving, where researchers saw donation rates measurably increase as campaigns approached their funding targets.
The behavior itself is interesting, but so is what’s driving it. The primary motivator isn’t pure altruism. It’s perceived personal impact. When a campaign is sitting at 92%, a donor doesn’t just see a number. They see an opportunity to be the one who pushes it over the finish line. That emotional payoff — the sense that their specific gift got the job done — is what really accelerates giving in the final stretch.
This is why a thermometer is more than a simple progress tracker. It’s constantly recalculating the psychological stakes for every donor who sees it. Early in a campaign, it builds awareness. But, as it climbs, it starts making individual donors feel increasingly consequential.
3. They make inaction feel like a lost opportunity
Loss aversion states that people are more motivated by the prospect of losing something than by the prospect of gaining something (even if it’s of equal value). We’d rather avoid a late fee than get an unexpected discount of the same amount.
A fundraising thermometer activates this instinct in a surprisingly direct way. When a campaign is visibly close to its goal, donors see more than an opportunity to chip in — they see a goal that could fail without them. That’s a different psychological trigger than simple momentum.
A thermometer near its target makes the cost of inaction feel real and specific. Research found that contributions doubled when donors were told a campaign was more than two-thirds of the way to its goal (versus less than one-third). And, while the goal gradient effect certainly plays a role there, it’s an increase that’s tough to explain by eagerness alone.
When a fundraising thermometer can work against you
The behavioral science cuts both ways. The same psychological triggers that drive donations can work in reverse — and a poorly configured thermometer can do more harm than good. Here are a few times when the science can flip on you:
- When your thermometer starts too low: A thermometer showing minimal progress early in a campaign can inspire skepticism rather than supportive social proof. Seeding your campaign with board gifts or offline donations before going public can help you avoid this.
- When your goal feels out of reach: The goal gradient only kicks in when the finish line feels attainable. A goal that seems too lofty undermines the entire effect. Put simply, donors can’t run toward a finish line they can’t even see.
- When you hit 100% and go quiet: Motivation usually dips sharply once a goal is reached, so it’s normal to see a drop in donations once you achieve your target. Announcing a stretch goal as soon as you hit your original mark keeps the psychological momentum going.
How to set up your fundraising thermometer
Now for the big question: How do you configure your thermometer to take advantage of the behavioral science?
Fundraise Up’s Goal Meter updates live with a count-up animation, tracks progress by dollar amount, total supporters, or recurring supporters, and can be embedded as a standalone element on any page of your website.
Here are a few tips to get the most out of it:
- Choose the right metric for your audience: Dollar amount and supporter count tell different stories. Supporter count tends to resonate with audiences motivated by community and belonging, while dollar amount works better when a matching gift or specific program cost is central to your campaign storytelling. You can toggle between the two — and even display both simultaneously.
- Pair it with social proof: Your thermometer shows progress, but recent donations show the people behind it. Placing Fundraise Up’s Social Proof element alongside your Goal Meter reinforces both signals at once. Donors see the momentum and the real people who are making it happen.
- Time your “almost there” push: Once a campaign hits roughly 70%, the goal gradient is working hard in your favor. That’s the moment to send the targeted email, board ask, or social post. Your thermometer is your most persuasive asset in this window, so make sure your outreach points people directly to it.
Most fundraising tools ask donors to care. A thermometer gives them a reason to act — and that distinction is what behavioral science keeps coming back to. Set it up thoughtfully, and it’ll do a lot more psychological heavy lifting than you’d ever expect from a seemingly simple colored bar.
Learn more about customizable digital fundraising Elements from Fundraise Up.