A woman at the bottom of a sumo deadlift, gripping the bar in a dark gym

Free tool by Coach.AI

Deadlift 1RM calculator

1RM = weight × (1 + reps / 30)

Enter a recent set of deadlifts and this deadlift 1RM calculator estimates what you could pull for one rep, without the risk of a max attempt on a tired back.

In the app: a test day. The weight to try is already in the field, worked out from your own sets.

Estimated deadlift 1RM

Enter a weight and reps to see your number.

On the deadlift the formula runs a little optimistic, so take 2.5-5 kg less for your first heavy attempt.

Percentages of your max

Handy when a program is written in percentages. Weights are rounded to what you can actually load, in steps of 2.5 kg or 5 lb, and the 100% row is rounded down, so it never asks for more than your estimate.

Weight at each percentage of your estimated one rep max
% of 1RM	Weight	Reps, about
100%	·	1
95%	·	2
90%	·	3
85%	·	5
80%	·	8
75%	·	10
70%	·	13
65%	·	16
60%	·	20

Heavy sets need longer breaks. How long to rest between sets.

Warm-up to your working weight

Before the first two lifts of a workout, Coach.AI puts two warm-up sets: half your working weight for 10 reps, then 70% for 5. Here are the same numbers for your weight.

Working weight

Warm-up50% × 10·
Warm-up70% × 5·
Working sets100%·

From the third lift of the day, one set of 8 at 60% is usually enough.

Want the reasoning behind those numbers? How many warm-up sets, and how heavy.

1RM = weight × (1 + reps / 30)

1RM formula: Epley and Brzycki

Pick a recent set that was hard but clean, ideally 3-8 reps. Type in the weight and the reps and the calculator does the rest. It uses the Epley formula: weight × (1 + reps / 30). For 80 kg × 8 that's 80 × (1 + 8/30), about 101.3 kg.

It's the same formula Coach.AI uses on every set you log, so the number here and the number in the app agree. A single rep is taken at face value: if 100 kg went up once, your 1RM is 100 kg.

Brzycki is the other formula you'll see: weight × 36 / (37 − reps). The two agree at 10 reps. Below that Brzycki comes out a little lower, about 4% at 5 reps (80 kg × 5 is 93.3 kg by Epley and 90 kg by Brzycki), and above 10 it climbs faster. Neither one is the true one. What matters is sticking with the same formula from week to week, so a change in the number means a change in you, not in the maths.

A few deadlift notes

Use reps where every pull started from the floor. Touch-and-go reps borrow a little bounce, so they make the estimate slightly optimistic. Setting the bar down each rep keeps the number honest.

Grip often gives out before your back and legs do. If the bar slipped out of your hands, the set measured your grip, not your deadlift.

When the number is off

Epley is at its best between 2 and 10 reps. Past that, how long you can keep going depends more on endurance than on strength, and the estimate drifts. Someone who loves sets of 15 looks stronger on paper than on the platform, and the heavy-triples crowd the other way round.

It also assumes the set ended close to failure. Eight reps with four more in the tank say little about your max, which is what the effort field is for. And a set on a tired Thursday reads lighter than you really are. That's fine: it's an estimate, not a verdict.

Questions people ask

How accurate is a 1 rep max calculator?

From a hard set of 3-8 reps it usually lands within a few percent of a tested max. The further you get from that range, the wider the miss. Use it as the starting point for your training weights, not as a number to brag with.

Do I need to test my real 1RM?

Not to train well. Most programs need your working weights, and the estimate gives you those just fine. If you do want to test, warm up properly, have a spotter or set the safety arms, and stop at the first rep that slows to a grind.

What percentage of my max should I train with?

Roughly 85% and up for heavy sets of 1-5, 70-85% for 6-12 reps aimed at muscle, and lighter for long sets. The table above turns each percentage into weight for you.

What are RPE and RIR?

Two ways of saying how hard a set was. RIR, reps in reserve, is how many more you could have done. RPE counts down from 10, so RPE 9 means one rep left and RPE 8 means two.

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Coach.AI

Let the app do this after every set

Coach.AI records your sets as you train and estimates your max from every one of them. When you open the next workout, the weight is already in the field, so you don't stand at the rack trying to remember what you lifted last week.

The first week of your .AI plan is free.