What Is One-Rep Max (1RM)?
Your one-rep max is the heaviest weight you can lift for exactly one repetition with proper form. It's the gold standard for strength—but testing it directly can be risky and taxing. A safer approach: use a sub-maximal lift (e.g., 5 reps at 100 kg) and plug it into a 1RM calculator to estimate your max.
Formulas like Brzycki and Epley are backed by research. Our 1RM Calculator supports multiple formulas and shows training percentages (e.g., 80% of 1RM for strength) so you can program without maxing out every week.
Training Percentages by Goal
Different percentages of your 1RM target different adaptations:
- 85–100% (1–5 reps): Maximal strength. Heavy singles, doubles, triples. Use sparingly—high fatigue.
- 70–85% (3–8 reps): Strength and hypertrophy. The sweet spot for most lifters.
- 60–70% (8–12 reps): Hypertrophy (muscle gain). Classic bodybuilding range.
- 50–60% (12–20 reps): Endurance and metabolic stress. Good for accessories.
Example: If your bench 1RM is 100 kg, 80% = 80 kg for 5–6 reps. 70% = 70 kg for 8–10 reps.
How to Use the Numbers in Your Program
Start with a recent heavy set (e.g., 5 reps at 90 kg). Enter it into the 1RM Calculator. You'll get an estimated 1RM plus a table of percentages. Use that table to set weights for your next block:
- Strength block: Work in the 80–90% range.
- Hypertrophy block: Work in the 65–75% range.
- Deload: Drop to 50–60% for a week.
Recalculating Over Time
Your 1RM changes as you get stronger. Re-test or re-estimate every 4–8 weeks. If you hit more reps than expected at a given weight, your 1RM has likely gone up—update your numbers and adjust your training loads accordingly.
Pro Tip: Pair the 1RM Calculator with Protein Intake to fuel recovery, and Calories Burned to track workout energy expenditure.