Squat 1RM
Calculator
Calculate your back squat one-rep maximum from a working set weight and rep count. Seven validated prediction formulas compared side by side — Epley, Brzycki, Lombardi, Mayhew, O’Conner, Wathen, and Lander — with an averaged estimate for reliable programming.
Estimate your squat one-rep max from a set you’ve hit, then read off training loads for every intensity. Averaged over seven validated formulas. Drag the sliders to update live.
Weight you squatted (kg)
Reps to failure (1–15)
Enter a weight and rep count to estimate your 1RM and training loads.
Averages Epley, Brzycki, Lander, Lombardi, Mayhew, O’Conner and Wathan. A 1RM estimate is only as honest as the set behind it — a hard set of 3–8 reps predicts best. Warm up and use a spotter before testing near-maximal loads.
What This Squat 1RM Calculator Does
This squat 1RM calculator estimates your back squat one-rep maximum from a submaximal working set — the weight you lifted and the number of reps completed. It applies seven independently derived prediction formulas and displays each result, alongside a seven-formula average and ready-to-use training load percentages.
1RM prediction from submaximal sets is standard practice in strength programming. It eliminates the need for maximal singles in training — which carry injury risk and require significant recovery — while still providing the reference point needed to set loading zones. For training principles: Progressive Overload Explained and Training Volume Explained. For bench press 1RM: Bench Press 1RM Calculator.
Seven 1RM Prediction Formulas — How They Differ
All seven formulas accept the same inputs — lifted weight (W) and rep count (R) — but were derived from different populations and use different mathematical structures. This is why they produce slightly different results. No single formula is superior across all individuals and loading conditions. Using the seven-formula average reduces the impact of any one formula’s systematic bias.
| Formula | Equation | Characteristic |
|---|---|---|
| Epley (1985) | W × (1 + R/30) | Most widely used. Linear rep-to-strength relationship. |
| Brzycki (1993) | W × 36/(37−R) | Performs well at low rep ranges (1–6). Less accurate above 10 reps. |
| Lombardi (1989) | W × R0.10 | Power function. More conservative estimates at high reps. |
| Mayhew (1992) | 100×W / (52.2 + 41.9×e−0.055R) | Exponential decay. Derived from football players. Suitable for athletic populations. |
| O’Conner (1989) | W × (1 + 0.025×R) | Linear, conservative. Slightly lower estimates than Epley. |
| Wathen (1994) | 100×W / (48.8 + 53.8×e−0.075R) | Exponential. Common in sports conditioning. Similar to Mayhew. |
| Lander (1985) | 100×W / (101.3 − 2.67×R) | Linear denominator. Performs well across moderate rep ranges. |
Which Formula to Use for Squat Programming
The Epley formula is the default recommendation for most lifters — it is the most widely validated, performs reliably across typical training rep ranges (3–8 reps), and is used as the primary estimate in this calculator. The seven-formula average reduces outlier influence and is the most robust single figure when formulas diverge by more than 5 kg. For low-rep working sets (1–3 reps), Brzycki is often more accurate than Epley. For high-rep sets (8–12), all formulas become less reliable — treat the result as a rough reference only.
Using Squat 1RM for Training Load and Periodisation
Percentage-Based Loading
Once 1RM is estimated, training loads are expressed as percentages of that maximum. Standard loading zones for squat training: 90–95% (heavy singles, peaking), 80–87% (strength sets, 3–5 reps), 70–79% (hypertrophy range, 6–10 reps), 60–69% (technique, volume, deload). The calculator outputs ready-to-use percentages at 70%, 80%, 85%, and 90% automatically — round to the nearest available plate combination on your bar.
When to Retest
Retest 1RM — either through a true maximum attempt or a new submaximal estimate — every 4–8 weeks during a training block, or whenever training weights have increased significantly. A 1RM estimated six months ago is not reliable for current programming. Update the reference point regularly to keep percentages accurate. If working weights are consistently feeling easier than the target RPE, your actual 1RM has increased and the estimate is stale.
Squat vs Bench vs Deadlift Ratio
In powerlifting, the conventional Big Three ratio for an intermediate lifter is approximately: Deadlift 100% : Squat 75–85% : Bench Press 55–65% of deadlift. A lifter deadlifting 200kg would typically squat 150–170kg and bench 110–130kg. Large deviations from this ratio indicate a lagging lift that warrants priority programming. See Bench Press 1RM Calculator for comparison.
Squat Technique Variables That Affect 1RM
Unlike the bench press, squat 1RM is highly sensitive to stance width, bar position, and depth standard — all of which affect leverages and the muscles primarily recruited. A lifter who tests 1RM with a high-bar close-stance squat will produce a different number than the same lifter using a low-bar wide-stance setup, even on the same day. For consistent 1RM tracking, always use the same squat variation. Do not compare high-bar estimates to low-bar estimates without adjustment.
Depth Standard
In powerlifting competition, a squat is valid when hip crease passes below the top of the knee — a standard that is strictly judged. Training 1RMs performed to this depth will be lower than estimates from partial-range squats. If your working sets are performed to competition depth and your 1RM test is not, the estimate will be inflated. Standardise depth in all sets used for 1RM estimation.
Belt and Equipment
A lifting belt increases intra-abdominal pressure and allows most lifters to squat 5–10% more than beltless. Raw knee sleeves add 1–3%. Squat suits (single-ply, multi-ply) add significantly more — 20–50% depending on equipment type. Never compare 1RMs across equipment categories. Estimate and track within a consistent equipment setup.
References
- Brzycki M. (1993). Strength Testing—Predicting a One-Rep Max from Reps-to-Fatigue. Journal of Physical Education, Recreation & Dance.
- LeSuer DA, McCormick JH, Mayhew JL, Wasserstein RL, Arnold MD. (1997). The Accuracy of Prediction Equations for Estimating 1-RM Performance in the Bench Press, Squat, and Deadlift. Journal of Strength and Conditioning Research.
- Macarilla CT, et al. (2022). Accuracy of Predicting One-Repetition Maximum from Submaximal Velocity in the Barbell Back Squat. Journal of Human Kinetics.
- Banyard HG, Nosaka K, Haff GG. (2017). Reliability and Validity of the Load-Velocity Relationship to Predict the 1RM Back Squat. Journal of Strength and Conditioning Research. PMID: 27669192.
- Marston KJ, Banyard HG, et al. (2022). Load-Velocity Relationships and Predicted Maximal Strength: A Systematic Review. PLOS ONE.
Squat 1RM Calculator — Key Takeaways
Use a 3–8 rep working set at RPE 8–9 for the most accurate 1RM estimate. Apply the Epley result for programming, cross-reference with the seven-formula average when formulas diverge. Retest every 4–8 weeks. Standardise squat variation, depth, and equipment across all estimates for valid comparison over time.
Final Educational Note
1RM estimates are mathematical predictions, not guaranteed maximum lifts. Actual performance on a given day is affected by sleep, nutrition, hydration, fatigue, warm-up quality, and psychological readiness. Treat the estimate as a programming reference, not a performance target to hit on any given session.
Nothing on this page constitutes coaching, medical, or training advice. MuscleScience.org does not provide coaching services. See our Disclaimer.
