One Rep Max Calculator
This tool estimates the maximum amount of weight you could lift for a single repetition (your “one rep max”) based on the weight you’re currently lifting and how many reps you can complete. It’s a valuable number for tracking strength progress, setting realistic training targets, and structuring effective workout plans.
Why It Matters:
Your one rep max isn’t just for powerlifters—it’s a benchmark for understanding your current strength level. Whether you’re doing 3 reps or 12, knowing your estimated max helps you choose the right weights for strength, hypertrophy, or endurance goals. It also allows you to adjust workouts as you get stronger.
How to Use Your One Rep Max (1RM) and Ten Rep Max (10RM) for Hypertrophy
Your estimated 1RM gives you a baseline to calculate ideal training weights. For hypertrophy (muscle growth), most programs recommend working at 65–85% of your 1RM. This usually means doing 6 to 12 reps per set.
If you prefer to use your 10RM, that’s often the exact weight you’d use for sets of 8–10 reps—the sweet spot for muscle growth. Use it to anchor your workout intensity without constantly testing maxes.
Sample Hypertrophy Training Based on 1RM:
70% of 1RM = ~12 reps
75% of 1RM = ~10 reps
80% of 1RM = ~8 reps
85% of 1RM = ~6 reps
Why Training Close to Failure Matters
To build muscle effectively, you need to challenge your muscle fibers enough to trigger growth. This doesn’t mean lifting until total exhaustion every time, but you should typically train within 1–3 reps of failure—where you could maybe push out one more rep with good form, but not much more.
This ensures you’re activating enough muscle without overdoing fatigue or risking injury. Especially on GLP-1 medications, which can suppress appetite and energy, training smart like this helps protect the muscle you’ve got while encouraging more growth.
For Those on GLP-1 Medications:
GLP-1 medications often lead to rapid weight loss, but without a strategy to preserve muscle, much of that loss can come from lean mass. Tracking strength levels through your estimated one rep max is a powerful way to make sure you’re maintaining (or building) muscle during weight loss. As your body changes, monitoring your strength helps you fine-tune your resistance training and protein intake to protect your metabolism and long-term health.
