Racketmeter lets badminton players measure string tension using the sound frequency produced when tapping the racket strings. It's 100% free, works in your browser on mobile and desktop, and requires no sign-up or installation.

I built it to solve a personal problem. I started playing badminton regularly in 2016 and quickly learned that players often ask stringers to string rackets at specific tensions (like 22 or 26 lbs). But after a few stringing jobs, I began to feel like the tension was inconsistent. Other players told me they just tap the strings and go by ear where "sharper sound meant higher tension."

One day while tuning my guitar, I could see exact sound frequencies on my tuner app. That’s when it clicked. It should be possible to build a tuner for badminton strings as well!

I searched online and found some tension-frequency data shared by professional stringers, but it wasn’t clean or comprehensive. So I visited 5 or 6 local stringers, gave them a frequency measuring app, and asked them to record racket head size, string thickness, tension, and sound frequency for each job. Some asked for a small payment, but most helped for free. Within a week, I had over 200 solid data points.

I trained a simple regression model using that data and validated it with newly strung rackets. It turned out to be surprisingly accurate. I shared it with friends and fellow players, and it started to spread in badminton forums.

There was another app that launched a few months later with big celebrity endorsements, but it was less accurate, harder to use, and required in-app purchases. Mine wasn't built to compete, but it ended up being more useful.

I originally released it as a mobile app, but constant changes in Google Play policies kept taking it down. So I rebuilt it as a simple browser-based tool.

Would love feedback, suggestions for improvements, or ideas on how to sustain it without cluttering it with ads or paywalls.

Let me know what you think.