Calculated Result
This section appears above the form after submission.
Summary
| Selected Formula | Average of all formulas |
|---|---|
| Lifted Set | 100.00 kg × 5 reps |
| Barbell + Collars | 20.00 kg |
| Per Side Plate Load | 31.25 kg |
| Plate Loading Status | Exact plate loading is available. |
Plate breakdown per side
1 × 25.00 kg 1 × 5.00 kg 1 × 1.25 kgFormula comparison
| Formula | Estimated 1RM |
|---|---|
| Epley | 116.67 kg |
| Brzycki | 112.50 kg |
| Lombardi | 117.46 kg |
| O'Conner | 112.50 kg |
| Wathan | 116.58 kg |
Warm-up ladder
| % of TM | Reps | Rounded Load |
|---|---|---|
| 40% | 8 | 42.50 kg |
| 55% | 5 | 57.50 kg |
| 70% | 3 | 72.50 kg |
| 80% | 2 | 82.50 kg |
| 90% | 1 | 92.50 kg |
Training load chart
Calculator Form
Example Data Table
| Example Input | Value | Example Output | Value |
|---|---|---|---|
| Lifted Weight | 140.00 kg | Estimated 1RM | 163.33 kg |
| Reps Completed | 5 | Training Max | 147.00 kg |
| Formula | Epley | Rounded Working Load | 117.50 kg |
| Bodyweight | 82.00 kg | Bodyweight Ratio | 1.99x |
| Bar + Collars | 25.00 kg | Per Side Plate Setup | 20 + 20 + 5 + 1.25 kg |
Formula Used
This calculator estimates one rep max from a completed squat set. It supports multiple formulas so you can compare conservative and aggressive estimates before choosing a training load.
Primary formulas
Epley: 1RM = Weight × (1 + Reps / 30)
Brzycki: 1RM = Weight × 36 / (37 - Reps)
Lombardi: 1RM = Weight × Reps^0.10
O'Conner: 1RM = Weight × (1 + 0.025 × Reps)
Wathan: 1RM = 100 × Weight / (48.8 + 53.8 × e^(-0.075 × Reps))
Load planning formulas
Training Max = Estimated 1RM × Training Max %
Target Working Load = Training Max × Target %
Rounded Load = Nearest chosen increment
Per Side Plate Load = (Rounded Load - Bar - Collars) ÷ 2
How to Use This Calculator
- Enter the heaviest completed back squat set and the reps you achieved.
- Choose kilograms or pounds, then pick one formula or the average option.
- Add bodyweight if you want a strength ratio and simple performance band.
- Set barbell weight, collar weight, smallest increment, and available plate sizes.
- Choose your training max percentage and the target percentage for the working set.
- Submit the form to see the result, warm-up ladder, plate loading, and chart.
- Use the CSV or PDF buttons to save the generated plan for coaching or training logs.
FAQs
1) Why does this calculator offer several formulas?
Different formulas model fatigue differently. Comparing them helps you avoid overestimating or underestimating your true back squat max from the same working set.
2) What rep range gives the best estimate?
Most lifters get the most useful predictions from sets of 1 to 10 reps. Higher reps can still work, but fatigue increases the estimation error.
3) Is training max the same as one rep max?
No. Training max is usually a reduced planning number, often 85% to 95% of estimated 1RM. It helps keep programming realistic and repeatable.
4) Why is the target load rounded?
Gyms use fixed plate jumps. Rounding makes the result practical so you can load the bar exactly or get as close as your equipment allows.
5) Why can plate loading fail to match exactly?
If the chosen increment or available plate sizes do not fit the rounded target, the calculator shows the leftover per-side load that cannot be matched.
6) Can I use this with pounds or kilograms?
Yes. The calculator accepts both systems, converts internally for accuracy, and also shows the estimated 1RM in the alternate unit.
7) Does squat depth or technique affect the estimate?
Yes. Consistent squat depth, bar position, bracing, and tempo matter. A formula cannot correct for changes in execution between sessions.
8) Is this useful for beginners?
Yes, especially when beginners use submaximal sets and conservative training max percentages. It can help structure progression without testing an all-out single often.