Turn Any Set Into Your Max and Plan Your Weights
Enter one set and get your estimated one-rep max, a likely range, and a table of training loads for every goal.
This tool was built by Serge (MSc) using established strength-training formulas. My background is a lifelong natural lifter with over a decade of drug-free training and a science background (MSc).
My tools are for educational purposes and give practical guidance, not professional advice.
Testing a true one-rep max is risky, especially without a spotter, so I prefer to estimate it from a set I can already do safely. That is what this tool is for.
Enter the weight and the reps you managed, and you will get an estimated max, a likely range, and a percentage table for planning your working sets. It is an estimate, not an exact figure.
| Percent of 1RM | Weight | Good for |
|---|---|---|
| 90% | Heavy strength, low reps | |
| 85% | Strength work | |
| 80% | Strength and size | |
| 75% | Muscle building | |
| 70% | Higher-rep sets |
Why I Estimate Instead of Testing
When I want a quick read on my strength, I take a hard set of a few reps and work out my max from it. That carries far less risk than grinding out a true max, and it is easy to repeat from one month to the next.
I recommend this approach to almost everyone, beginners especially. You learn what you can do without putting your joints, or your confidence, on the line.
The Two Formulas Behind It
The tool uses two well-known strength formulas, Epley and Brzycki, and averages them for a balanced estimate. Both take the weight you lifted and your reps and project what you could manage for a single rep.
The fewer reps you enter, the more accurate the estimate, because the projection is smaller. Sets of 3 to 6 reps give the most reliable result.
Choosing Weights From the Table
The percentage table turns your estimate into training loads. Lower reps at higher percentages build strength, while higher reps at lower percentages build size and endurance, so pick the row that matches your goal.
Treat each number as a starting point and adjust to how the weight feels on the day. If you train in the other unit, the kg to lbs converter will switch the numbers for you, and the plate loading calculator shows which plates make each weight.
Where This Falls Short
This is an estimate, not a measured max. Your true one-rep max depends on the exercise, your technique, your fatigue, and how you respond to heavier loads.
It is least accurate at high rep counts, so keep your reps low for the best guide. Always warm up properly and use a spotter or safety bars near your limit.
What to Use Next
Once you have your max, the warm-up set calculator builds the ramp-up sets that lead to your working weight, and the strength standards calculator shows how that number compares for your bodyweight.
To keep it climbing, the progressive overload calculator tells you when to add weight, and my Natural Beginner's Muscle Blueprint turns it all into a 12-week plan.