Your Estimated Max
Training Loads By Percentage
| % of Max | Load | Typical Reps |
|---|---|---|
| Calculate your max to see loading targets | ||
How the Shrug Max Calculator Works
A one-rep max (1RM) is the heaviest weight you can lift for a single, complete repetition with proper form. Testing a true 1RM is fatiguing and carries injury risk, so most lifters and coaches estimate it instead, using the weight and reps from a submaximal set performed close to failure. This calculator runs your set through three of the most widely used estimation formulas and averages the results, since no single formula is perfectly accurate for every lifter, rep range, or lift.
The Epley Formula
Developed by Boyd Epley, this is the most commonly cited 1RM formula in strength and
conditioning: 1RM = weight × (1 + reps / 30). It assumes a roughly
linear relationship between reps and percentage of max, and tends to run slightly higher
than other formulas at higher rep counts.
The Brzycki Formula
Matt Brzycki's formula uses a different curve: 1RM = weight × 36 / (37 − reps).
It's generally considered more accurate at lower rep ranges (1–10) and is the formula
behind many printed gym percentage charts.
The Lombardi Formula
An older formula from exercise scientist Vittori Lombardi: 1RM = weight × reps^0.10.
It produces a more conservative estimate than Epley at high rep counts, which is useful as
a sanity check against the other two.
Why Shrug Maxes Are Rarely Calculated — And Why That's a Mistake
Shrugs are a grip-limited movement more than a true strength-limited one for most lifters, so your estimated max is often really a grip-endurance ceiling. Straps will meaningfully raise the weight you can move for the same rep count, so keep your grip method consistent between the set you enter here and the sets you plan around this number. Because range of motion is short, bar speed changes less with fatigue than in a squat or deadlift, so shrug estimates hold up reasonably well even at 10–12 reps.
Using the Percentage Table
Once you have an estimated max, the percentage table above gives you target loads for common training zones: heavy singles and doubles near 90–95%, strength work in the 80–85% range, and volume/hypertrophy work from 60–75%. These are starting points — adjust based on how the bar actually moves that day.
Limitations of Any 1RM Formula
- Accuracy drops as rep count increases past about 10–12 reps.
- Formulas assume the set was taken close to failure with consistent bar speed.
- Individual fatigue resistance, fiber type, and technique efficiency all shift the true number up or down.
- A calculated max is a planning estimate, not a guarantee of what you can lift on a given day.
Informational Use Only
This calculator provides estimates for training-planning purposes only. It is not a substitute for professional coaching, in-person technique assessment, or medical advice. Estimated one-rep max values can vary meaningfully from a lifter's actual performance. Always warm up progressively, use a spotter or safety bars when testing heavier loads, and stop immediately if you experience pain. GymMaxCalculators.com and its owners assume no liability for injury, loss, or damage arising from the use of this tool or reliance on its output. Consult a qualified coach, trainer, or physician before attempting a new maximal lift.