MuscleRx Strength Tool

1RM Calculator

Use the sliders to estimate your one-rep max in real time, save your lifts by exercise, and track weekly progression.

Live 1RM Estimate

135 lb
8 reps
Estimated 1RM
171.0 lb
Calculated with the Epley formula.
Recommended Zone
75–85% = Growth + Strength
Best range for quality muscle-building work with strong form.
Technique / Volume Max Effort

Percentages of 1RM and Training Uses

% of 1RM Weight Use

Saved 1RM History

Stored in your browser
No saved entries yet. Save a lift to start tracking progression.

Weekly Progression Tracker

Save multiple entries for the same exercise across different weeks to track strength trends.

How to Use 1RM Percentages

90–100% is your max-effort zone. Use it for testing, low-rep strength work, and occasional exposure—not every session.

75–85% is the sweet spot for a blend of strength and muscle growth. Most MuscleRx users should spend a lot of productive time here.

60–70% is ideal for technique, controlled volume, recovery sessions, and learning to own the movement with strict form.