What is a 1 rep max?

Your one rep max (1RM) is the heaviest weight you can lift for a single repetition with proper form. It's the gold standard for measuring absolute strength and is used as a baseline for percentage-based training programs.

Rather than actually maxing out — which carries injury risk — most lifters estimate their 1RM from a submaximal set. If you can bench 225 lb for 5 reps, this calculator estimates what you could bench for 1 rep.

How formulas work

All 1RM formulas use the same inputs — weight lifted and reps completed — but apply different mathematical models. The most common ones:

• Epley: 1RM = weight × (1 + reps / 30). The most widely used formula and the one Titan uses internally to track estimated 1RM over time.
• Brzycki: 1RM = weight × 36 / (37 - reps). Tends to give slightly lower estimates than Epley at higher rep ranges.
• Lombardi: 1RM = weight × reps^0.1. A simpler power-law model.
• Mayhew: Uses an exponential decay model. Generally agrees with Epley for moderate rep ranges.
• O'Conner: 1RM = weight × (1 + reps / 40). More conservative than Epley.

All formulas are most accurate for sets of 1-6 reps. Above 10 reps, estimates become unreliable — which is why this calculator caps input at 10.

Using your 1RM for programming

Once you know your 1RM, you can calculate working weights for any percentage-based program:

• Strength (85-95% 1RM): Heavy sets of 1-5 reps. Used in peaking phases and powerlifting programs.
• Hypertrophy (65-80% 1RM): Moderate sets of 6-12 reps. The bread and butter of muscle-building programs.
• Endurance (50-65% 1RM): Lighter sets of 12-20+ reps for muscular endurance and conditioning.

Many programs use a Training Max (TM) — typically 85-90% of your true 1RM — as the base for percentage calculations. This builds in a buffer for sustainable progression. Titan supports both %1RM and %TM natively in its program builder.