Question 1

Is the 1RM estimate accurate?

Accepted Answer

1RM estimates are generally accurate within 5-10% when using reps in the 3-10 range with proper form. Accuracy decreases for very high reps (15+) or when fatigue affects the lift. For the most accurate estimate, use a weight you can lift for 3-6 reps with good form.

Question 2

Which formula is best?

Accepted Answer

There's no single 'best' formula — each has strengths. Epley is most common and works well for moderate reps (4-10). Brzycki is conservative and better for lower reps (1-6). Lombardi handles higher reps better. The Auto mode averages all three for the most balanced estimate.

Question 3

Should beginners use 1RM?

Accepted Answer

Beginners can use 1RM estimates for programming, but shouldn't attempt actual 1RM lifts. Focus on learning proper form first. After 2-3 months of consistent training, you can use this calculator to estimate your 1RM from your working sets.

Question 4

How often should I recalculate my 1RM?

Accepted Answer

Recalculate every 4-6 weeks, or whenever you complete a training block. Your 1RM should increase over time as you get stronger. If it's not increasing, review your training program, nutrition, and recovery.

Question 5

Is this for bodybuilding or powerlifting?

Accepted Answer

Both! Bodybuilders use 1RM to program hypertrophy training (typically 70-85% of 1RM). Powerlifters use it to peak for competitions (heavier percentages). The training percentage table helps both approaches.

Question 6

Does it matter if I use kg or lb?

Accepted Answer

Not at all. The formulas work with any weight unit — just be consistent. Enter your weight in whichever unit you prefer, and the results will be in the same unit.

Question 7

Why are my results different with different formulas?

Accepted Answer

Each formula was developed from different research data and athletic populations. Variations of 5-10% between formulas are normal. If you're unsure which is most accurate for you, use Auto mode for a balanced average.

Question 8

Can I use this for isolation exercises?

Accepted Answer

These formulas were designed for compound barbell exercises (bench, squat, deadlift, press). They may be less accurate for isolation exercises, machines, or cable work where movement patterns are different.

Question 9

What if I did more than 15 reps?

Accepted Answer

Estimates become unreliable above 15 reps. If you can do 15+ reps, the weight is too light for accurate 1RM estimation. Test with a heavier weight in the 3-10 rep range for better accuracy.

Question 10

How do the strength levels work?

Accepted Answer

Strength levels (Beginner to Elite) are based on commonly accepted strength standards for each lift. These are general guidelines for a typical adult lifter. Individual factors like bodyweight, training age, and genetics affect where you fall on the scale.

% of 1RM	Weight	Typical Reps	Training Goal
100%	115.5 kg	1	Max Strength
95%	109.7 kg	2	Peak Strength
90%	104 kg	3-4	Strength
85%	98.2 kg	5-6	Strength/Power
80%	92.4 kg	6-8	Hypertrophy
75%	86.6 kg	8-10	Hypertrophy
70%	80.9 kg	10-12	Muscle Endurance
65%	75.1 kg	12-15	Endurance
60%	69.3 kg	15-20	Conditioning
50%	57.8 kg	20+	Warm-up/Recovery

Formula	Equation	Best For
Epley	Weight × (1 + Reps/30)	4-10 reps
Brzycki	Weight × 36/(37 - Reps)	1-10 reps
Lombardi	Weight × Reps^0.10	10-15 reps

One Rep Max Calculator

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