How to estimate your one rep max

You squat 100kg for 5 reps. Someone asks: what’s your max? You don’t know, because you’ve never tried a single rep with the heaviest weight you can handle. But you can estimate it with surprising accuracy.

Your one rep max - the maximum weight you can lift for a single repetition with good form - is one of the most useful numbers in strength training. It benchmarks your strength, drives percentage-based programming, and tracks your progression over months and years.

Here’s how to calculate it without actually risking a max attempt.

What a one rep max is

Your 1RM is the heaviest weight you can lift for one complete rep with proper form. Not a half rep. Not a grinder with your back folded in half. One clean rep, full range of motion.

It represents your peak force production on a given lift at a given point in time. It’s affected by sleep, nutrition, stress, and even time of day. A true 1RM on a bad day can be 5-10% lower than on a good day.

For most lifters, knowing your estimated 1RM is more useful than knowing your actual tested 1RM. The estimate is close enough for practical purposes and doesn’t require the risk of a maximal attempt.

The main estimation formulas

Several formulas exist for estimating 1RM from submaximal data. They all work similarly for low rep ranges and diverge at higher rep ranges.

Epley formula

The most widely used formula:

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

Example: You squat 100kg for 5 reps. 1RM = 100 x (1 + 5/30) = 100 x 1.167 = 116.7kg

Simple, easy to calculate in your head, and reasonably accurate for 1-10 reps.

Brzycki formula

A slightly different approach that gives very similar results for low rep ranges:

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

Example: You squat 100kg for 5 reps. 1RM = 100 x (36 / (37 - 5)) = 100 x (36/32) = 100 x 1.125 = 112.5kg

The Brzycki formula tends to give slightly lower estimates than Epley, especially at higher rep ranges. For 5-rep sets, the difference is small.

Which one to use

For 5x5 purposes, either formula works. The Epley formula is simpler to calculate and is the one most commonly referenced. For a 5-rep set, the two formulas give estimates within about 4% of each other.

The real takeaway: your 5-rep max is approximately 85-87% of your 1RM. That’s the practical number to remember.

5RM to 1RM reference table

Here’s a quick reference based on the Epley formula. Find your 5-rep working weight and read across for your estimated 1RM.

5-rep weight	Estimated 1RM	5-rep weight	Estimated 1RM
20kg	23kg	80kg	93kg
30kg	35kg	90kg	105kg
40kg	47kg	100kg	117kg
50kg	58kg	110kg	128kg
60kg	70kg	120kg	140kg
70kg	82kg	140kg	163kg

These are estimates. Your actual 1RM could be 5-10% higher or lower depending on your individual strength profile.

Why your estimated 1RM matters

Tracking long-term progress

Your 5-rep max going from 60kg to 80kg is meaningful, but comparing across different rep ranges is harder. If you squat 60kg for 5 last month and 55kg for 8 this month, which is better? Converting both to estimated 1RM (70kg vs 69.7kg) makes the comparison straightforward.

Over months of training, your estimated 1RM should trend steadily upward even through deloads and program changes. It’s a more stable measure than your daily working weight.

Transitioning to percentage-based programs

When you move from 5x5 to a program like 5/3/1 or Madcow, you need a 1RM to calculate your working weights.

5/3/1 uses a “training max” set at 90% of your 1RM. If your estimated 1RM squat is 120kg, your training max is 108kg, and your working weights for the cycle are calculated from there.

Getting this number right matters. Set it too high and you’ll fail early. Set it too low and you’ll waste weeks on weights that are too light. Using your most recent 5-rep max with the Epley formula gives you a reliable starting point.

Pro tip: When setting up a new percentage-based program, use the lower of the two formula estimates (Brzycki) or take 90% of your Epley estimate. Starting slightly conservative is always better than starting too heavy. Jim Wendler himself advises starting 5/3/1 “too light.”

Comparing relative strength

Your absolute 1RM doesn’t tell the whole story. A 100kg squat means very different things for a 60kg lifter versus a 100kg lifter.

Relative strength (1RM divided by body weight) gives a fairer comparison:

Relative squat	Level
0.75x bodyweight	Untrained
1.0x bodyweight	Beginner
1.5x bodyweight	Intermediate
2.0x bodyweight	Advanced
2.5x+ bodyweight	Elite

These are rough benchmarks, not rigid standards. They vary by age, sex, and body weight class. But they give you context for where your strength sits relative to your size.

On 5x5, most lifters progress from the untrained to intermediate range within 6-12 months. Tracking your relative strength over time shows progress even when body weight changes.

Understanding your training zones

Once you know your estimated 1RM, you can understand what percentage of your max you’re working at:

Percentage of 1RM	Reps possible	Training effect
90-100%	1-3	Maximal strength, neural
80-90%	3-6	Strength (this is where 5x5 lives)
70-80%	6-12	Hypertrophy and strength
60-70%	12-20	Muscular endurance

Your 5x5 working weight falls in the 80-87% range of your 1RM. This is the sweet spot for strength development - heavy enough to build maximal strength, light enough to practice technique over multiple sets.

Why you probably shouldn’t test your 1RM

If you’re running 5x5, you almost certainly don’t need to test your actual 1RM. Here’s why.

Maximal singles are a skill

Grinding out a heavy single is a specific ability that requires practice. Your body needs to be trained for maximal effort - bracing harder than on a set of 5, moving more slowly, maintaining composure under a bar that feels impossibly heavy.

Without practice, your actual 1RM will likely be lower than your estimated 1RM. This doesn’t mean the estimate is wrong - it means you haven’t developed the skill of maxing out. That’s fine, because you don’t need that skill unless you’re competing.

Injury risk increases at maximal loads

The risk of injury scales with the percentage of your max. A set of 5 at 85% carries less injury risk than a single at 100%. Form breakdown is more likely, muscles and tendons are under greater absolute stress, and there’s less margin for error.

For a beginner who’s been lifting for a few months, the motor patterns aren’t deeply ingrained enough to maintain form under true maximal load. The technique that holds up at 85% may not survive at 100%.

Your 5x5 data is sufficient

You don’t need to know your exact 1RM for 5x5. The program doesn’t use percentages - it uses progressive overload. You add weight when you complete the reps. You deload when you fail. The 1RM is irrelevant to the day-to-day operation of the program.

When you eventually transition to a percentage-based program, your estimated 1RM from your last 5x5 weights is a perfectly good starting point.

Recovery cost

A true max attempt is fatiguing. Working up to a 1RM on squat can take 6-8 warm-up sets and leave you drained for 2-3 days. That’s training time and recovery capacity spent on a number you could have calculated from your existing data.

If you’re in the middle of a productive 5x5 run - adding weight every session, feeling good - interrupting that to max out is counterproductive. The data you get isn’t worth the disruption to your training.

How to test safely (if you really want to)

Sometimes you just want to know. Maybe you’re curious. Maybe you’re planning to compete. Maybe you’ve been training for a year and want to see how your estimated 1RM compares to reality. That’s valid.

Preparation

• Don’t test while fatigued. Skip the heavy training 2-3 days before. A light session the day before is fine.
• Pick one lift. Testing multiple 1RMs in one session adds fatigue that compromises later attempts. Test squat one day, bench another.
• Eat and sleep well. Maximal attempts on a calorie deficit or after 5 hours of sleep won’t represent your true capacity.

The warm-up protocol

A smart warm-up ramp for testing a 1RM (estimated at 120kg):

Set	Weight	Reps	Purpose
1	Bar (20kg)	10	General warm-up
2	50kg	5	Movement practice
3	70kg	3	Increasing load
4	90kg	2	Approach weight
5	105kg	1	Heavy single
6	115kg	1	Near-max single
7	120kg	1	1RM attempt

Key points:

• Reps decrease as weight increases to conserve energy
• Rest 3-5 minutes between the heavier sets
• If 115kg felt very heavy, skip the 120kg attempt. Your max is around 115kg today.
• If 120kg goes up, rest 5 minutes and try 125kg. Don’t take more than 3 total attempts at 95%+ or fatigue will skew results.

Safety requirements

• Power rack with safety bars. Non-negotiable for squat and bench.
• Spotter. Ideally someone experienced who knows when to help and when not to.
• Belt (optional). If you normally use one, use it for the max attempt. If you don’t, don’t start now.
• Clear head. If you’re distracted, stressed, or not feeling it, skip the test. There’s no urgency.

Tracking your estimated 1RM over time

Your estimated 1RM is one of the best metrics for long-term progress. Here’s a realistic timeline of estimated squat 1RM for a typical male beginner starting 5x5:

Month	Working 5x5 weight	Estimated 1RM
1	40kg	47kg
2	55kg	64kg
3	70kg	82kg
4	82.5kg	96kg
6	95kg	111kg
9	107.5kg	125kg
12	115kg	134kg

These numbers assume consistent training, adequate nutrition, and typical deload cycles. Your numbers will vary, but the trajectory matters more than the absolute values. A steadily rising estimated 1RM means the program is working.

If your estimated 1RM plateaus for more than a month despite deloads and recovery adjustments, that’s a strong signal that you’ve exhausted linear progression and need to consider a new approach.

The formulas in reverse: setting weights from a 1RM

When you transition to a percentage-based program, you’ll work backward from your 1RM to determine working weights.

Epley reversed: weight = 1RM / (1 + reps/30)

If your estimated 1RM squat is 120kg and your program calls for 5 reps at 80%:

• 80% of 120kg = 96kg
• Or: 120 / (1 + 5/30) = 120 / 1.167 = 102.8kg (this gives the weight you’d use for a 5-rep max)

For 5/3/1, remember to use 90% of your 1RM as your training max:

• 1RM = 120kg
• Training max = 108kg
• Week 1 working sets: 65% of 108 = 70kg, 75% of 108 = 81kg, 85% of 108 = 92kg

Starting with your last successful 5x5 weight, plugging it into the Epley formula, and using the result as your 1RM gives you a smooth, accurate starting point for any percentage-based program.

The bottom line

Your 5-rep weight multiplied by 1.167 gives you a solid 1RM estimate. That number is useful for tracking progress, comparing strength, and transitioning to new programs.

You don’t need to actually lift your 1RM to know it. The formulas are accurate enough for practical purposes, and the risk of a max attempt isn’t worth the marginal precision gain - especially while you’re still making linear progress on 5x5.

Lift, log, and let the math handle the rest. For a deeper understanding of how weight increases, deloads, and plateaus fit together, read the complete progression guide.

Every workout automatically updates your estimated 1RM:

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