Sports

One Rep Max (1RM) Calculator

Q: Which of the 3 formulas is most accurate?

**None wins across all ranges**. **Brzycki** is more accurate at 1-5 reps (heavy sets near failure). **Epley** is better at 5-10 reps (hypertrophy range). **Lombardi** tends to overestimate at 10+ reps. The **average of all 3** is the most robust strategy because it smooths individual errors -- that's what this calculator gives as the primary result.

Q: Does the formula work for any exercise?

It works well for **compound movements**: squat, deadlift, bench press, overhead press, barbell row. It's **less accurate for isolation exercises** and highly technical movements: bicep curls, lateral raises, leg press, Olympic lifts. Reason: **local fatigue** and **technique** distort results more in smaller movements.

Q: What is the ideal rep range for estimating 1RM?

**Between 3 and 8 reps to failure**. Fewer than 3 reps: it's nearly an actual 1RM, making the estimate pointless. More than 10 reps: the formula loses precision because other factors (muscular endurance, aerobic system) come into play. **Sweet spot**: test with **5 reps to failure** -- heavy enough to be accurate, light enough to be safe.

Q: What is 'training max' and why use 90% of 1RM?

The **Training Max (TM)** is the 1RM you use for programming daily training, typically **90% of actual 1RM**. Popularized by **Jim Wendler in 5/3/1**. **Why not use actual 1RM**: your 1RM varies day to day by +/-5-10% due to sleep, nutrition, and stress. If you program at 100%, you'll fail prescribed reps frequently. Using TM at 90%, your '85% set' is really 76.5% of true 1RM -- totally executable.

Q: Can I estimate 1RM from a set with reps in reserve (RIR)?

**Yes, by adjusting the reps**. If you did **100 kg x 6 reps with RIR 2** (you had 2 reps left), add 2 to the reported reps: treat it as **100 kg x 8 reps to failure**. Apply the standard formula. **Advantage**: test 1RM without actually going to failure (less risk, better recovery). **Caveat**: estimating RIR is a skill -- novices tend to overestimate their proximity to failure.

Q: Do women need different formulas?

**No, the same formulas are valid for both sexes** -- they work on the muscular system, which responds the same way. What changes are the **absolute values** (women typically have 60-70% of men's upper body strength at the same weight, 80-85% for lower body). This calculator works identically for men and women.

Q: How do I break through a strength plateau?

**Five proven tactics**: **1) Deload** (a week at 60% of TM) every 4-6 weeks. **2) Change rep ranges** (if doing 5x5, try 10x3 or 3x10 for 4 weeks). **3) Exercise variations** (front squat instead of back squat, incline press vs flat). **4) Accessory work** on weak links (triceps, upper back, core). **5) Sleep more and eat in a surplus** -- 70% of 'plateaus' are insufficient recovery, not insufficient training.

Q: How often should I update my 1RM in my program?

Depends on your level: **Beginners** (0-6 months): every **3-4 weeks** (rapid progress). **Intermediates** (6 months-2 years): every **6-8 weeks**. **Advanced** (2+ years): every **10-16 weeks** or end of each cycle. **Signs to retest**: you're doing **2-3 more reps** than the program prescribes, or you have 3+ RIR on heavy sets.

Estimate your 1RM without risk: enter weight and reps, get estimates from 3 validated formulas plus a percentage table for periodization.

Data verified · July 2026
Edited by Martín Rodríguez
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Edited by: Martín Rodríguez (editorial policy )

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Jul 2, 2026 — Rewrote the summary comparing Epley, Brzycki and Lombardi with a worked example.

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1RM Back Squat Calculator — Estimate Your Max (Epley Formula)Enter weight and reps to instantly estimate your back squat 1-rep max using the Epley formula. Includes a %1RM table and strength standards for novice to elite lifters.1RM Calculator (One Rep Max)Free 1RM calculator using the Epley formula. Enter any weight and reps and get your estimated one rep max plus 3RM, 5RM, 8RM, 10RM and 12RM for programming.Bench Press 1RM EstimatorCalculate your bench press one-rep max using the Brzycki formula. Free strength training calculator.Rest Time Between Sets by Training IntensityCalculate optimal rest periods between sets based on intensity (% 1RM) and training goal. Free, fast, science-based.

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If you did 8 reps of 80 kg (176 lbs) on squat, what's your max for a single rep? The 1RM (One Repetition Maximum) is the heaviest weight you can lift once with correct form, and it's the key variable for periodizing any strength program: all serious programs (5x5, Wendler 5/3/1, Westside, Sheiko) prescribe loads as % of 1RM. But testing your actual 1RM is risky (tears, hernias, drops) and exhausting (requires 3-5 days recovery). This calculator applies 3 validated formulas: Epley (1985), Brzycki (1993), and Lombardi (1989) -- the three scientific references from the NSCA (National Strength and Conditioning Association) and Jim Wendler. Enter the weight and reps performed to failure (ideally 2-10 reps), and get the estimated 1RM from each formula + the average + a percentage table for training programming.

When to use this calculator

You want to periodize training by % of 1RM without risking an actual max test.
You're coming back from injury and want to use controlled loads based on your estimated 1RM.
You run 5/3/1 Wendler or 5x5 Stronglifts and need your 'training max' (90% of 1RM).
You want to compare your 1RM with powerlifting standards (Wilks, IPF, DOTS).
You're a coach calculating 1RM from training logs to adjust loads for athletes.

Reps-to-1RM Percentage Table (NSCA standard)

Reps to Failure	% of 1RM	Training Goal	Typical Sets
1	100%	Max strength test	1
2	95%	Near-max / peaking	1–2
3	93%	Maximal strength	2–3
4	90%	Strength	3–4
5	87%	Strength / power	3–5
6	85%	Strength–hypertrophy	3–5
8	80%	Hypertrophy	3–4
10	75%	Hypertrophy / endurance	3–4
12	70%	Hypertrophy / metabolic	3–4
15	65%	Muscular endurance	2–3

Source: NSCA – Essentials of Strength Training and Conditioning; Epley (1985), Brzycki (1993) formulas. Percentages are approximations; individual variation ±3–5%.

How it works

The 3 Formulas

Epley (1985)

1RM = weight x (1 + reps / 30)

Origin: Boyd Epley, founder of the Nebraska strength program. The most widely used by coaches and apps (Strong, Hevy, FitNotes). Accuracy: excellent in 3-10 rep ranges.

Brzycki (1993)

1RM = weight x 36 / (37 - reps)

Origin: Matt Brzycki, Princeton. More conservative at high reps. Accuracy: better than Epley in 1-6 reps, worse in 10+.

Lombardi (1989)

1RM = weight x reps^0.10

Origin: V. Patteson Lombardi, physiologist. Used in powerlifting and weightlifting. Accuracy: tends to overestimate at 10+ reps.

Practical advice: the average of all 3 is more robust than any single formula -- it smooths out individual errors.

Rep-to-1RM Reference Table

Approximate 1RM percentage based on reps to failure:

Reps to Failure	% of 1RM
1	100%
2	95%
3	93%
4	90%
5	87%
6	85%
7	83%
8	80%
9	77%
10	75%
12	70%
15	65%

Reverse use: if you did 100 kg x 5 reps, your 1RM = 100 / 0.87 = 115 kg.

Prilepin's Table (Optimal Volume by % 1RM)

Soviet scientist A. S. Prilepin analyzed thousands of Olympic weightlifting sessions:

% 1RM	Rep Range/Set	Optimal Total Reps	Goal
55-65%	3-6	18-30	Warm-up, technique, endurance
70-80%	3-6	12-24	Hypertrophy
80-90%	2-4	10-20	Strength / myofibrillar hypertrophy
90-95%	1-3	4-10	Maximal strength
95-100%	1-2	1-4	Peaking / competition

The 5/3/1 Method (Jim Wendler)

Uses Training Max = 90% of actual 1RM for 4-week periodization:

Week	Sets x Reps	% TM
1	5/5/5+	65/75/85%
2	3/3/3+	70/80/90%
3	5/3/1+	75/85/95%
4 (deload)	5/5/5	40/50/60%

1RM Standards by Level (Men, 176 lbs / 80 kg)

Reference from Strength Level based on 100,000+ users:

Exercise	Beginner	Intermediate	Advanced	Elite
Squat	132 lbs	253 lbs	375 lbs	507 lbs
Deadlift	165 lbs	308 lbs	441 lbs	595 lbs
Bench Press	99 lbs	198 lbs	297 lbs	397 lbs
Overhead Press	66 lbs	132 lbs	198 lbs	275 lbs

When to Retest

Beginner (< 6 months): every 4-6 weeks (rapid gains).

Intermediate (1-3 years): every 8-12 weeks.

Advanced (3+ years): every 12-16 weeks or at the end of each periodization cycle.

Common Mistakes

1. Testing with more than 10 reps: the formula breaks down. Stick to 2-10 reps for accuracy.
2. Not going to failure: if you held back 2 reps, the estimated 1RM will be 10-15% too low.
3. Form breakdown on final reps: reps with compromised technique shouldn't count.
4. Applying to isolation exercises: works well for squat, deadlift, bench press, overhead press. Less accurate for curls, lateral raises, leg press.
5. Treating estimated 1RM as actual 1RM: it's an estimate. For competition 1RM, test for real.

Example: Squat, 80 kg (176 lbs) for 8 reps to failure

Weight: 80 kg.

Reps to failure: 8.

Epley: 80 x (1 + 8/30) = 80 x 1.267 = 101.3 kg.

Brzycki: 80 x 36 / (37 - 8) = 80 x 36 / 29 = 99.3 kg.

Lombardi: 80 x 8^0.10 = 80 x 1.232 = 98.6 kg.

Average: (101.3 + 99.3 + 98.6) / 3 = 99.7 kg.

Training max (90%): 99.7 x 0.90 = 89.7 kg.

Estimated 1RM: ~100 kg on squat. For training, use 90% as your training max (89.7 kg). With that, your 5-rep set at 80%: ~72 kg x 5. Your AMRAP at 85%: ~76 kg to failure (target: 8+ reps). Retest 1RM every 8-12 weeks.

Frequently asked questions

Which of the 3 formulas is most accurate?

None wins across all ranges. Brzycki is more accurate at 1-5 reps (heavy sets near failure). Epley is better at 5-10 reps (hypertrophy range). Lombardi tends to overestimate at 10+ reps. The average of all 3 is the most robust strategy because it smooths individual errors -- that's what this calculator gives as the primary result.

Does the formula work for any exercise?

It works well for compound movements: squat, deadlift, bench press, overhead press, barbell row. It's less accurate for isolation exercises and highly technical movements: bicep curls, lateral raises, leg press, Olympic lifts. Reason: local fatigue and technique distort results more in smaller movements.

What is the ideal rep range for estimating 1RM?

Between 3 and 8 reps to failure. Fewer than 3 reps: it's nearly an actual 1RM, making the estimate pointless. More than 10 reps: the formula loses precision because other factors (muscular endurance, aerobic system) come into play. Sweet spot: test with 5 reps to failure -- heavy enough to be accurate, light enough to be safe.

What is 'training max' and why use 90% of 1RM?

The Training Max (TM) is the 1RM you use for programming daily training, typically 90% of actual 1RM. Popularized by Jim Wendler in 5/3/1. Why not use actual 1RM: your 1RM varies day to day by +/-5-10% due to sleep, nutrition, and stress. If you program at 100%, you'll fail prescribed reps frequently. Using TM at 90%, your '85% set' is really 76.5% of true 1RM -- totally executable.

Can I estimate 1RM from a set with reps in reserve (RIR)?

Yes, by adjusting the reps. If you did 100 kg x 6 reps with RIR 2 (you had 2 reps left), add 2 to the reported reps: treat it as 100 kg x 8 reps to failure. Apply the standard formula. Advantage: test 1RM without actually going to failure (less risk, better recovery). Caveat: estimating RIR is a skill -- novices tend to overestimate their proximity to failure.

Do women need different formulas?

No, the same formulas are valid for both sexes -- they work on the muscular system, which responds the same way. What changes are the absolute values (women typically have 60-70% of men's upper body strength at the same weight, 80-85% for lower body). This calculator works identically for men and women.

How do I break through a strength plateau?

Five proven tactics: 1) Deload (a week at 60% of TM) every 4-6 weeks. 2) Change rep ranges (if doing 5x5, try 10x3 or 3x10 for 4 weeks). 3) Exercise variations (front squat instead of back squat, incline press vs flat). 4) Accessory work on weak links (triceps, upper back, core). 5) Sleep more and eat in a surplus -- 70% of 'plateaus' are insufficient recovery, not insufficient training.

How often should I update my 1RM in my program?

Depends on your level: Beginners (0-6 months): every 3-4 weeks (rapid progress). Intermediates (6 months-2 years): every 6-8 weeks. Advanced (2+ years): every 10-16 weeks or end of each cycle. Signs to retest: you're doing 2-3 more reps than the program prescribes, or you have 3+ RIR on heavy sets.

Sources & references

Update history

Log of data, formula and content changes for this calculator.

Jul 02, 2026Rewrote the summary comparing Epley, Brzycki and Lombardi with a worked example.

Methodology & trust

Editorial

Sports calculator with its formula verified automatically against Epley B. - Poundage Chart (1985), per our editorial policy and methodology.

Updates

Updated: July 2026. Parameters are verified periodically against the cited sources.

Privacy

Calculations run 100% in your browser. We do not store or transmit your data.

Limitations

Indicative results. For critical decisions, consult a professional.

📌 How to cite this calculator

Rodríguez, M. (2026). One Rep Max (1RM) Calculator. Hacé Cuentas. https://hacecuentas.com/en/one-rep-max-calculator

Content licensed under CC-BY 4.0 — reuse it citing the source with a link to Hacé Cuentas.

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