Skip to main content

Strength Charts

Track your estimated one-rep max (1RM) over time with interactive line charts for every exercise.

Estimated 1RM​

HyperIron calculates your estimated 1RM from every qualifying set using the average of two formulas:

  • Epley: 1RM = weight × (1 + reps / 30)
  • Brzycki: 1RM = weight × 36 / (37 - reps)

The average of both formulas gives a reliable estimate across rep ranges. Epley tends to read slightly higher at higher reps and Brzycki slightly lower, so averaging smooths the bias of either formula alone.

References​

  • Epley, B. (1985). Poundage Chart. Boyd Epley Workout. Lincoln, NE: Body Enterprises.
  • Brzycki, M. (1993). "Strength Testing—Predicting a One-Rep Max from Reps-to-Fatigue". Journal of Physical Education, Recreation & Dance. 64 (1): 88–90. doi:10.1080/07303084.1993.10606684.
  • LeSuer, D. A.; McCormick, J. H.; Mayhew, J. L.; Wasserstein, R. L.; Arnold, M. D. (1997). "The Accuracy of Prediction Equations for Estimating 1-RM Performance in the Bench Press, Squat, and Deadlift". Journal of Strength and Conditioning Research. 11 (4): 211–213. — comparison of Epley, Brzycki, and other rep-max prediction equations.

What qualifies​

  • Only full-ROM reps — Partial reps are excluded
  • Only the Weight resistance type — Bands, machines, cables don't contribute (no universal equivalence)
  • All set types contribute — A drop set entry of 225×8 gives the same estimate as a straight set of 225×8
  • Tempo does not adjust estimates — Slow tempo makes the set harder but doesn't change your max

Reading the chart​

The strength chart shows your estimated 1RM plotted over time:

  • X-axis: Date
  • Y-axis: Estimated 1RM (lbs or kg)
  • Each point: Your best estimate from that session

An upward trend means you're getting stronger. Plateaus or dips might indicate fatigue accumulation, the need for a deload, or a program change.

Filtering​

  • By exercise: Select any exercise to see its progression
  • By date range: Zoom into a specific period
  • By set type: Default shows straight sets only for clean trend lines. Optionally include all set types.

Tips for useful data​

  • Log consistently — Gaps in data make trends harder to read
  • Use the same resistance type — Your barbell bench 1RM and machine chest press are tracked separately
  • Don't chase 1RM estimates — They're derived from submaximal work. Focus on following your program; the estimates track your progress automatically.