The 10RM (Ten Rep Max or Ten Repetition Maximum) is the weight you can do exactly 10 reps with. For example, if you did a set of 100 kg for 8 reps, you can use a 10RM calculator to work out that your 10RM was 95 kg. That means you could have done 95 kg for 10 reps.
Since your 10RM strength is normalized to 10 reps, sets with different reps are comparable. For example, if you do a set with 105 kg for 8 reps and another with 95 kg for 12 reps, the 10RM is 100 kg in both cases. This way, you can immediately see that your performance was the same in both sets.
Also, the 10RM can be used to evaluate your progress very well: If the 10RM increases (in the long term), you will become stronger—no matter what the weight and reps look like.
To find out what your 10RM is for a particular exercise, check out our Rep Max calculator.
Since this is a lot of math in training, the Alpha Progression app will automatically calculate the 10RM for each set. You can also see the development of the 10RM of an exercise in the graphs. You can immediately see from the graph if you are progressing.
In addition to the 10RM, there is the 1RM, which follows the same principle but, as the name implies, calculates how much weight you can move for 1 rep.
An often-used alternative to the 10RM is training volume. However, this is inferior because it "rewards" high reps far too much. By only considering the training volume, you could have a "fake progression" by doing more reps and using far less weight.