What it is
This tool calculates a lifter’s one‑rep max (1RM) from the weight they can lift for a specified number of repetitions using the Epley or Brzycki prediction formulas. The resulting 1RM estimate and a training weight at a chosen percentage help athletes select appropriate loads for training, monitor progress, and avoid overreaching.
How to use: Enter your lift data and select the appropriate parameters for an instantaneous estimate. Adjust the percent to fit your training goals (e.g., 80–90% of 1RM for strength work, 60–75% for hypertrophy). After submitting, the calculator instantly shows both the estimated one‑rep max (1RM) and a practical training load to aid program planning and progress tracking.
How to use it
Enter your lift data and select the appropriate parameters for an instantaneous estimate. Adjust the percent to fit your training goals (e.g., 80–90% of 1RM for strength work, 60–75% for hypertrophy). After submitting, the calculator instantly shows both the estimated one‑rep max (1RM) and a practical training load to aid program planning and progress tracking.
Worked example
Start with a 70 kg lift performed for 8 reps and select the Epley formula. Step 1: Apply the Epley equation: 1RM = 70 × (1 + 8/30) ≈ 88.6667 kg, rounded to +/- 0.001 kg → 88.667 kg. Step 2: Calculate training weight at 80%: 0.8 × 88.6667 ≈ 70.9333 kg, rounded → 70.933 kg.
Inputs
- Lifted Weight: 70
- Unit: 1
- Repetitions: 8
- Formula: 1
- Training % of 1RM: 80
Result
- Estimated 1RM: 88.667
- Training Weight at %1RM: 70.933
Frequently asked questions
What is the difference between the Epley and Brzycki formulas?
Epley’s formula (Weight × (1 + Reps/30)) assumes a linear relationship between reps and load and tends to be more conservative; Brzycki’s version (Weight ÷ (1 + 0.0333×(Reps‑1))) yields higher estimates for low repetition ranges.
What % of my 1RM should I use for training?
A common guideline is 80–90% of 1RM for strength work with 3–6 reps, 60–75% for hypertrophy, and <50% for endurance or technique. Select the percentage that matches your program’s phase.