📖 Overview
Use standard powerlifting formulas to estimate your theoretical one-rep maximum based on sub-maximal repetitions.
🧪 Example Scenarios
Use these default and higher-pressure example inputs to explore how sensitive this calculator is before using your real numbers.
| Input | Base Case | Higher Pressure Case |
|---|---|---|
| Weight Lifted | 225 | 258.75 |
| Repetitions Completed | 5 | 5.75 |
⚙️ How It Works
Estimates your theoretical one-repetition maximum (1RM) weight based on a sub-maximal set using the widely accepted Epley formula.
The Formula
1RM = Weight × (1 + Reps / 30)
💡This calculator is scenario-based. Better input quality leads to better decision quality.
Quick Reference
| Input | Example Value |
|---|---|
| Weight Lifted | 225 |
| Repetitions Completed | 5 |
When To Use This
- Use this tool when you need a fast decision during active planning or execution.
- Use this before committing money, time, or tradeoffs that are hard to reverse.
- Use this to compare options using the same assumptions across scenarios.
Edge Cases To Watch
- Results can be misleading if key inputs are missing, stale, or unrealistic.
- Very small or very large values may amplify rounding effects and interpretation risk.
- If assumptions change mid-decision, recalculate before acting.
Practical Tips
💡 Most accurate for rep ranges of 2–10. Accuracy decreases significantly above 10 reps.
💡 Use this to set training zones: strength (85–100% 1RM), hypertrophy (65–85%), and endurance (<65%).
💡 Always use an experienced spotter when attempting a true physical maximum lift.
Frequently Asked Questions
❓ Which 1RM formula is most accurate?
Epley and Brzycki are both widely used. Epley tends to predict slightly higher and is common in powerlifting contexts.
❓ Should I attempt my estimated 1RM?
Use the estimate for planning training loads, not as a regular lifting target, as maximal attempts carry injury risk.