I've been lifting weights on and off for years — nothing impressive, just trying to stay functional and not get hurt. And every few months, I run into the same small frustration: I want to test my strength on a lift like the bench press or squat, but I don't want to actually max out. Loading up a weight I can barely handle for one rep feels risky, especially without a spotter.
The standard solution is to use a "one-rep max calculator." You take a weight you can lift for multiple reps (say, 185 lbs for 5 reps), plug it into a formula, and it estimates your theoretical 1RM. Simple idea — but most of the calculators I found online were either buried in ad-filled blog posts, required me to sign up for something, or gave me a number without any context.
I just wanted a clean, no-fuss page where I could type in two numbers and get an answer. No push upsells, no "try our training program!" pop-up. Just the estimate, using the common Epley formula, with a brief explanation of what it means.
I'm not claiming this is groundbreaking. But I think it's a genuinely better experience because it's just a calculator. It doesn't track your workouts, it doesn't require an email, and it shows the result in a way that's easy to copy or screenshot. I also added a simple strength-standards reference (based on common tables) so you can see roughly where you stand — not as a "you must be this strong to ride" gate, but as a general sanity check.
Plus, it works on your phone, and it's fast. That's really it.
You enter two things: the weight you lifted (in pounds or kilograms) and the number of reps you completed. The tool uses the Epley formula to estimate your one-rep max. It also shows the estimated max for a few other rep ranges (like 3RM, 5RM) if you want to plan your next workout. It rounds to a sensible number, and it's all client-side — no data leaves your browser.
Try the calculator here →
One-Rep Max CalculatorThis tool isn't going to change your life. It's just a simple utility for a specific moment: when you want to estimate your max without actually going for it. If that's useful to you, great. If not, that's fine too. I built it because I needed it, and I figured I'd share it. No strings attached.
— Built at ToolsForUse · No signups · No tracking