Most Zone 2 calculators use one formula. This runs all three — MAF, Karvonen, and % of Max HR — simultaneously so you see the full picture. Enter your age, resting heart rate, and fitness level. Get your Zone 2 range three ways, a complete 5-zone training table, weekly volume recommendations, and plain-English explanations. Free. No signup. No email. Built for runners, cyclists, and anyone serious about aerobic base training and longevity.

Layout Agent 2.0 — Thinks before it builds

Thinks before it builds

Hey Product Hunt! 👋 I built this because I kept running into the same frustration — every Zone 2 calculator online picks one formula and gives you a single number, with zero explanation of why different methods produce different results. MAF, Karvonen, and percentage of Max HR all give different Zone 2 ranges — and they're all "correct" depending on your situation. So I built a tool that runs all three simultaneously and explains the science behind each. Enter your age, resting heart rate, and fitness level. You get: → Zone 2 range calculated three ways side by side → Complete 5-zone training table → Weekly training volume recommendations → Plain-English explanation of each method Free. No signup. No email. Works on mobile. Would genuinely love feedback from anyone who trains by heart rate — especially if the numbers feel off for your experience level. Happy to answer any questions about the methodology!

Hey👋

I built this because most Zone 2 calculators felt too simplistic or inconsistent.

This one shows 3 methods side-by-side so you can compare and choose what works best for you.

Curious — how are you currently tracking your Zone 2 training?

Would love your feedback 🙏