It’s Thursday, I’m Nithya Sudhir. I collect words, chase patterns, and write about whatever makes me curious.
Comparison is the thief of joy?
Online shopping, I’d argue, is a hard task that can easily turn into an unpaid research project.
Do you agree?
You have to search, filter, add the product to a wishlist, evaluate, and, most importantly, compare multiple products to get to the best one.
Before, we had to open multiple product pages in separate tabs and then compare the features manually or visually.
Today, to help you pick, most product pages today have a small, square, checkbox that does that for you.
☐ Compare
Tick a couple of boxes, and voila! Everything you need, sorted into neat little boxes, quietly promising you can have it all.
For many stores, this feature quietly does a lot of work. 78% of online shoppers use comparison shopping before buying, and for categories like electronics, 72% consider two or more models, and 57% visit five or more brand sites before deciding.
In Baymard Institute’s usability testing, 67% of participants used comparison features when shopping for specification-heavy products.
Today we’re talking about the compare feature and looking at why it feels so satisfying?
Do you actually use comparison tools when shopping online?
This is the final edition of Interface Instincts, my six-part series on the tiny design decisions shaping how we shop online.
Let's get into it.
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From bargain hunting to browser tabs
Let’s go back to the mid-90’s for a bit.
The first comparison shopping tool on the internet was built in 1995, a year before most people had even heard the word "ecommerce."
It was called BargainFinder, built by researcher Bruce Krulwich as an experiment, to solve a new problem of the early internet: fragmented online stores.
It quietly scanned early online music retailers and returned prices for the same CD across all of them, no warning given to the sites being compared.
A few years later, a Seattle startup called Netbot built Jango, one of the first commercial shopping agents.
Around the same time, a Bay Area startup called Junglee built similar technology and was acquired by a young company called Amazon.
The Backlash
Some retailers were furious.
This new technology threatened to turn their digital storefronts into commodities.
If shoppers only looked at the lowest price, brand loyalty, site design, and customer service would matter far less.
After spending years trying to block it, they decided to do something smarter: handing comparison engines clean, structured data on purpose, prices, stock, shipping costs, feeding platforms like the early Google Shopping directly.
That cooperation eventually swallowed the whole category.
Comparison shopping stopped living on separate websites and moved inside the store itself.
The buy box: Comparison you never see happening
On Amazon today, when a shopper looks at a product, a background algorithm is already running a live comparison across every seller offering that same item, weighing price, shipping speed, and seller rating to decide who wins the "Buy Box," the default seller shown to the shopper.
Did you know, up to 90% of sales on Amazon are made from the Buy Box, making it one of the highest-stakes, most invisible comparison tools in ecommerce.
Why the checkbox feels good
Comparing isn't just useful. It's a relief.
It lets us test the regret before buying
Before we've even made a decision, the brain runs a quiet simulation of "what if I'd chosen the other one," and that simulation happens in the orbitofrontal cortex, a region tied to processing both the experience and the anticipation of regret. Comparing two products side by side lets you run that simulation before you buy instead of after.
It changes the reference point
Philosopher John Locke noticed this centuries before ecommerce existed: lukewarm water feels hot or cold depending only on which hand touches it first, the hand that was just in cold water, or the one that was just in hot water.
Nothing about the water changes. Only the reference point does.
The same thing happens on a product page.
A $79 wallet feels expensive on its own. Placed next to a $140 wallet, it suddenly feels reasonable. Shoppers rarely judge value in a vacuum. They judge it against whatever's sitting right next to it.
“Which one?” is easier than “How good?”
In 1927, psychologist Louis Thurstone found something in his Law of Comparative Judgment: people are far more reliable when comparing two things directly than when rating either one alone.
Ask someone to rate a wallet "1 to 10" and you'll get a shrug. But ask them "this one or that one" and they'll answer instantly and confidently.
This is the real reason the compare button works. It's not that people need more information. It's that a direct comparison is a mentally easier question to answer than an absolute one.
A comparison gives the shopper a reference point and a smaller question to answer.
The compare button works because choosing between visible alternatives is often easier than judging a product in isolation.
Bellroy innovates the comparison
Most comparison tools ask, “Which of our products do you want?”
Bellroy asks more useful questions: How will this look on your body? How big will it feel in your hand? How much bulk will it remove from your pocket?
Its comparison tools change the reference point at every stage.
Bellroy’s “Compare Sizes” feature lets shoppers view bags on their own or on models of different heights. Instead of comparing measurements such as 38 cm and 42 cm, shoppers can see how each bag sits on an actual body.
On product pages, they use a tool called Tangiblee that lets shoppers compare a wallet's actual size against everyday objects they already own and can picture instantly: an iPhone, a key, a credit card, placed right next to the product.
Then, there’s Bellroy’s Slim Your Wallet, a slider labeled "Empty" on one end and "Full" on the other. Drag it, and an image shows a wallet visibly shrinking or expanding, the bulk you'd actually be carrying.
The comparison isn't Bellroy versus another brand.
It's the shopper's current, overstuffed wallet versus a slimmer one, using their own hands to control the outcome.
It’s the kind of comparison that Thurstone's research says people find easiest to judge.
What Bellroy does beautifully is it contrasts the shopper's present problem against their own possible future, which sidesteps the tab-hopping, competitor-researching spiral a table can accidentally invite.
The practical checklist
If you're actually building a compare feature, CXL's guidelines are the most thorough reference out there.
Here are the essentials, condensed:
Pick your format on purpose. A compare tool, a filter, or a standalone page, decide based on how many products and specs you're dealing with.
Confirm the action. When someone adds a product to compare, show them it worked and tell them what to do next.
Keep the compare tray visible. A sticky bar or accessible indicator, don't make shoppers hunt for what they've selected.
Use the convention. A simple checkbox labeled "Compare" near the product image. Familiar beats clever here.
Let people act from the comparison itself. Add to cart, click through to the full product page, no dead ends.
Make exiting easy. A clear "back to results" or close button.
Let people save or share it. Email or print the comparison, some purchase decisions involve more than one person.
Explain the jargon inline. Hover definitions for technical specs, don't send shoppers elsewhere to decode a term.
Keep every row consistent. Same specs, same naming, no empty cells across products.
Show ratings prominently. Right there in the comparison, not buried on each product page.
Skip it entirely if it's not needed. If the product list page already shows every meaningful difference, a separate comparison page just adds a click.
The best comparison tools do not help shoppers examine more.
They help them eliminate faster.
That's a wrap on Interface Instincts.
hank you for reading every single one of these with me.
If you want to see more such breakdown on design elements, or want me to write more stories on UI/UX let me know in your replies!
This is me signing off!
How's the depth of today's edition?
As always, hit reply if something in here hits home.
Until next week,
Nithya
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