Calculator
Use clean curl form. Momentum, shoulder swing, and partial range can overstate your estimated max.
Example data table
| Weight | Reps | Bodyweight | Formula | Estimated 1RM |
|---|---|---|---|---|
| 20 kg | 8 | 75 kg | Average of all | 25.37 kg |
| 25 kg | 5 | 82 kg | Epley | 29.17 kg |
| 30 lb | 10 | 170 lb | Brzycki | 40.00 lb |
| 17.5 kg | 12 | 68 kg | Lander | 24.29 kg |
Formula used
The calculator supports several common one-rep-max equations. The main estimate uses your selected formula, then applies optional adjustments for RPE, training experience, and single-arm conditions.
Epley: 1RM = Weight × (1 + Reps ÷ 30)
Brzycki: 1RM = Weight × 36 ÷ (37 − Reps)
Lander: 1RM = Weight × 100 ÷ (101.3 − 2.67123 × Reps)
Lombardi: 1RM = Weight × Reps0.10
Average mode: Uses the mean result from all included formulas to reduce single-formula bias.
These equations are estimations. Strict curl execution usually gives better predictions than loose technique or swinging reps.
How to use this calculator
- Enter the heaviest curl weight you completed with solid form.
- Select the exact number of full repetitions performed.
- Choose kilograms or pounds for all entries.
- Add your bodyweight to assess relative arm strength.
- Select a formula, arm mode, experience level, and session RPE.
- Press the calculate button to view your 1RM estimate above the form.
- Review the load table and charts for planning sets.
- Download your result as CSV or PDF when needed.
Frequently asked questions
1. Is a bicep curl 1RM estimate accurate?
It is a practical estimate, not a guaranteed true max. Accuracy improves when reps are strict, range is full, and you stop shoulder swing or body English.
2. Which formula should I choose?
Average mode is a balanced default. Epley is popular for moderate reps, while Brzycki often works well in lower rep ranges. Compare results when unsure.
3. Why does bodyweight matter here?
Bodyweight lets the calculator show relative strength. This helps compare arm strength across different lifter sizes instead of only using absolute load numbers.
4. Can I use this for dumbbell curls?
Yes. Enter the actual load used for the curl style you performed. For single-arm dumbbell curls, select single-arm mode for a slightly more conservative estimate.
5. What rep range works best for estimating 1RM?
Most formulas work best from about 1 to 10 reps. This calculator accepts up to 15, but lower rep sets usually give stronger predictions.
6. Why does RPE change the result?
A set at RPE 8 usually leaves more reps in reserve than a set at RPE 9 or 10. The adjustment helps reflect that effort difference.
7. Should I test an actual curl max?
Most lifters do not need to. Estimated maxes are safer for elbows and wrists, especially during arm isolation work where form can break quickly.
8. How often should I recalculate?
Recalculate when your working weights, rep quality, or bodyweight change meaningfully. Many lifters update every few weeks during a focused training block.