The Evolution of Perfitt’s Fit Engine: From Obsession to Global Adoption
1. Introduction — Why Fit Still Matters
The global footwear industry is worth over $500 billion, yet one of its most basic challenges remains unsolved: fit.
80% of online shoppers hesitate to buy shoes because they are unsure about sizing.
35% of online footwear orders are returned, most due to poor fit.
Even in physical stores, 75% of shoppers leave dissatisfied with the fitting experience.
Behind every return is a frustrated customer. Behind every pile of unsold stock is a brand losing trust.
Perfitt was founded to change this reality — through a journey that began with small, imperfect steps but never lost sight of a single obsession: building the world’s most precise Fit Engine.
2. Where It All Began — A Personal Struggle
For me, this wasn’t just a business opportunity; it was a lived frustration. Growing up, basketball was my greatest passion. I admired players like LeBron James and dreamed of wearing the same shoes. But as an Asian woman, I could never find basketball shoes in my size.
The only options were oversized men’s models or ill-fitting boys’ sneakers. I tried thick socks, insoles, anything to make them work. The result? Blisters, sprained ankles, hallux valgus, and plantar fasciitis.
Later, working as a consultant at IBM, I realized that despite my professional path, my real calling was clear: to solve this universal problem of footwear fit.
Perfitt was born from that conviction.
3. The Early Grind (2018–2019) — Perfitt R and the First Breakthroughs
Our first step into this challenge came in 2018 with the launch of Perfitt R, an in-store foot measurement device.
Inside the machine was a carefully integrated camera connected to a tablet, a seemingly simple idea that took months of iteration. With this device, we began knocking on doors of brands and retailers, explaining our vision and persuading them to give us a chance.
The largest New Balance store in Seoul’s Gangnam district agreed.
S-Market, a multi-brand retailer, also gave us space.
There, we stood face-to-face with customers, measuring their feet and asking them about their experiences with fit. The reactions were unforgettable: “This is so accurate.” “That’s amazing.” “Thank you, I’ve always wondered about my exact foot shape.”
At marathon events, runners lined up to learn about their own feet. Many had never been told their arch type or exact measurements, and when they finally saw the results, they smiled, laughed, and even thanked us simply for the information.
It was encouraging, but it was also clear: hardware could never scale globally. We knew we had to take this technology out of stores and into everyone’s pocket — through the one device every person carried: a smartphone.
4. From Hardware to Smartphone (2020–2022) — Building the Perfitt App
This transition was harder than we imagined. At first, we mailed out a foldable paper footplate (the Perfitt Kit) that users could assemble and use to anchor their heel. It was cheap enough to send by regular post, and although it took longer to arrive, customers were surprisingly patient. Some even posted “Perfitt Kit unboxing” photos on social media, turning the wait into a moment of excitement.
But paper kits could never scale. We spent more than two years experimenting with ways to let people measure their feet using common household items: coins, banknotes, credit cards, business cards, A4 paper. Each came with problems — size variations, privacy risks, lack of standardization. Eventually, only A4 paper passed the test.
With this breakthrough, we built a method where users could place their foot on an A4 sheet, photograph it with their smartphone, and receive measurements accurate to ±1mm.
To train our AI, we collected and processed over 10 million images. We obsessed over edge cases: the shadows of living room lamps, patterned socks, tilted phone angles, even nail polish colors. Our engineers worked night after night, fixing one scenario after another until the algorithm was robust enough to handle the chaos of real-world photos.
In 2020, we launched the Perfitt app.
The results:
700,000 users joined organically in just two years.
300,000+ unique foot profiles collected.
2.5 million size recommendations delivered.
A conversion rate of 10–14%, far above e-commerce averages.
We also leveraged our co-founder’s retail background. She sourced test volumes of leftover shoes — pairs stranded in “size breaks” that retailers struggled to sell. Our app matched those orphaned shoes with the right feet. Users got perfect-fit bargains; retailers cleared impossible inventory.
For the first time, technology didn’t just make shopping easier — it turned waste into value.
5. Entering B2B (2023) — PerfittSize Beta
The app proved the need, but we soon realized: to truly change the industry, we had to empower brands and retailers directly.
So in 2023, we launched PerfittSize Beta, our first B2B SaaS solution. The journey from app to enterprise was anything but simple.
First challenge: bringing foot scans to the web.
Until then, accurate foot measurement required our mobile app. But between 2021 and 2022, web technologies advanced enough that we could overlay real-time guide lines in a browser. Leveraging this, we built a solution where brands could integrate PerfittSize with just a few lines of JavaScript — no heavy SDKs, no friction. It was a turning point: scalability without complexity.
Second challenge: automating product data.
Every brand had its own way of labeling products — model names, codes, SKU formats. If integration meant manual tagging, no retailer would adopt it. We invested deeply in methods to standardize and auto-ingest product data, so retailers could go live without dedicating entire tech teams.
Third challenge: going global.
When Gucci’s Innovation HQ invited us to run a PoC on their U.S. site, we faced a simple but critical issue: the U.S. doesn’t use A4 paper. It uses Letter size. We had to retrain and revalidate our algorithms on new scale references, ensuring accuracy under pressure. Meanwhile, U.S. traffic volumes stress-tested our still-beta platform.
Even more revealing: we discovered that many American households didn’t keep Letter paper at home. This insight pushed us to fast-track a paperless measurement technology we had been researching in parallel. Midway through the PoC, we deployed it. The result? A 6x jump in user conversion rates. It was one of those rare moments in R&D when persistence met breakthrough.
And yet, even with these wins, it wasn’t easy. Adoption required constant persuasion. We were walking a path no one had paved before. There were no benchmarks, no manuals — only trial, error, and grit.
6. First Year of Adoption (2024~) — PerfittSize Official
By late 2023, after countless refinements, our solution stabilized. In January 2024, we launched PerfittSize Official as a full SaaS product.
That year, we signed contracts with 12 B2B clients in Korea, from footwear brands to multi-brand retailers.
What resonated most with our clients was not the technology itself, but the problems it solved:
For new brands entering Korea, customers had no prior sizing experience. Choosing the right size was guesswork. Perfitt removed that uncertainty.
For multi-brand retailers, inventory spanned hundreds of models with different sizing quirks. Perfitt standardized the experience, reduced confusion, and built customer trust.
For everyone, the promise was the same: higher conversions, fewer returns, and — just as importantly — a sense of confidence for shoppers.
Another layer of value quickly emerged: data. Clients realized that the more their customers used PerfittSize, the more insights they gained into actual foot shapes, size preferences, and product-specific feedback. What began as a conversion tool was now also a data intelligence platform, helping brands improve merchandising and plan inventory smarter.
This second layer — data utilization — is what Perfitt is now most focused on in 2025: turning fit into not just a solved problem, but a strategic advantage for the industry.
7. Conclusion — Spirit That Built It
Looking back from 2018 to today, Perfitt’s story is defined by three values:
Agility — If there was even one way to try, we tried it.
Customer-First — Every feature was born from user pain or client demand.
Never Give Up — Even when experts said, “This is impossible.”
“If fit was an unsolved problem, we chose to be the ones stubborn enough to solve it.”
When people see Perfitt today, they see a polished, precise Fit Engine trusted by global brands. What they don’t see are the hundreds of failures, the endless late nights, the prototypes that didn’t work, and the unwavering belief that kept us going.
Perfitt was never just about reducing returns or improving conversions. From day one, our obsession with fit has been about something bigger: helping every person find and connect with the products that truly fit them best. Because when the right fit is unlocked, people move with more freedom, more confidence, and more authenticity.
We are creating a world where products and experiences adapt to each individual — not the other way around. A world where everyone can live out their own lifestyle, rich and unique to who they are.
Don’t bend yourself to fit the world. Be yourself.