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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 two formulas:

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

For sets of 10 reps or fewer, the estimate is the average of both formulas — Epley tends to read slightly higher and Brzycki slightly lower, so averaging smooths the bias of either formula alone. Above 10 reps, the estimate is Epley alone: Brzycki's denominator (37 - reps) approaches zero as reps climb toward 37, so it becomes unreliable for high-rep sets.

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)
  • Every working set counts — There's no straight-sets-only restriction; a set of 225×8 gives the same estimate however you performed it (a straight set, a drop, or a rest-pause effort)
  • Tempo does not adjust estimates — Slow tempo makes the set harder but doesn't change your max
  • Bodyweight and Bodyweight+ count too — a pure bodyweight set (no added weight) has nothing to estimate from under the External lens, but switch to Total or ×BW (see below) and your session bodyweight fills that in

Lenses​

The chart header has an External / Total / ×BW pill:

  • External (default) — your estimated 1RM from the weight you added, same math as always.
  • Total — includes your bodyweight's contribution (session bodyweight × the exercise's factor), so weighted pull-ups, dips, and similar exercises reflect real load rather than just the plate weight.
  • ×BW — your estimated 1RM as a multiple of bodyweight (e.g. 1.80×), for comparing relative strength independent of body size.

Your choice is remembered on this device. See Reading Your Data for how the same lenses apply to volume charts and PR/heaviest drill-downs.

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.

Sharing the chart​

The share icon in the chart's header exports your trend as a branded 1080×1920 image — current estimated 1RM, the change over the period, and the trend line, in whatever timeframe, program filter, and lens you have selected. On mobile it opens the share sheet or saves to your photo library; on the web it shares through the browser's share sheet, or downloads as a PNG when sharing isn't available. The consistency heatmap has the same share icon for your gym-days grid. See Sharing Workouts for details.

Filtering​

  • By exercise: Select any exercise to see its progression
  • By date range: Zoom into a specific period

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.