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.
Enter weight and reps to see your 1RM.
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.
What should I do first on this page?
Start with the minimum required inputs or the first action shown near the primary button. Keep optional settings at defaults for a baseline run, then change one setting at a time so you can explain what caused each output change.
Why does this page differ from another tool?
Different pages often use different defaults, units, rounding rules, or assumptions. Align those settings before comparing outputs. If differences remain, compare each intermediate step rather than only the final number.
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