How to use (3 steps)
- Start with a recent set (e.g., 100 kg × 5 reps). Pick the formulas you trust; the default blend shows a median.
- Choose your unit, rounding increment, and whether to use Training Max (TM). Rounding assumes total barbell weight.
- Switch tabs for a % table or reverse calc, then copy the summary, table, or share link for your program.
Heavy lifting carries risk. Stay within your skill level, warm up well, and stop if form breaks down.
Use the sample set or enter your own weight and reps, then compute to refresh the estimate.
Formula results
Shown in your selected unit. The difference column compares each formula to the recommended value.
| Formula | 1RM | Difference |
|---|
% table
Rounded column is what to load; raw shows the unrounded math.
| % or reps | Rounded | Raw |
|---|
Use this with your workout log or spreadsheet. Rounding matches the increment above.
Reverse result
How it's calculated
- Epley, Brzycki, O'Conner (plus optional Lander, Mayhew, Lombardi) convert weight × reps into estimated 1RM.
- Recommended 1RM uses the median by default to mute outliers; switch to mean if you prefer an average.
- Training Max multiplies 1RM by the % you set (90% by default) and can drive the table/reverse modes.
- Rounding applies to total weight with nearest/floor/ceil. Use smaller increments (1-1.25) for micro-plates.
- Rep tables and reverse reps use the Epley inverse (% = 1 / (1 + reps/30)). Very high reps carry more error.
FAQ
Which 1RM formula should I use?
Epley and Brzycki are common for 1-10 reps; O'Conner is similar. Differences grow at high reps, so stay near singles to tens when possible and pick the blend (median/mean) you trust.
What is Training Max (TM)?
TM is a planned percentage of 1RM (often 90%). It keeps working weights conservative for volume blocks. Toggle it on, set the percent, and the table and reverse calc will use TM as the base.
How do rounding increments work for barbells and dumbbells?
The increment is applied to the total weight shown. For a barbell, divide plates evenly per side after rounding. For single dumbbells, halve the rounded total to know one hand's weight.
Should I base working weights on 1RM or on Training Max?
Use 1RM if you want the raw estimate from your best set. Use Training Max when you plan volume work or want conservative loading. The TM toggle applies the percentage you choose, typically 85–90%, before building tables or reverse targets.
Why do different formulas give different 1RM numbers?
Each formula models the rep-to-max relationship slightly differently, especially above about 10 reps. The page shows several formulas side by side so you can compare spread and choose a median or mean instead of trusting a single estimate.
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