e1RM — what an estimated max is
The weight a formula says you could lift once, worked out from a set of several reps.
e1RM is your estimated one-rep max. You did 100 kg for 5 — the Epley formula says you could lift about 117 kg once. You don't need to test it with a real max: an estimate is easier to compare from workout to workout, even if you always train for 5–8 reps.
There are several formulas. Epley: weight × (1 + reps ÷ 30). Brzycki: weight × 36 ÷ (37 − reps). They nearly agree on short sets and drift apart on long ones — which is why I leave sets longer than 12 reps out. If you give an RPE, the reps in reserve get added: 100 kg for 5 at RPE 8 counts like 7 reps to failure.
The diary works out e1RM for every set; the best one in a workout goes to the chart and to your records. That's how I see whether you're growing or stuck — and it's the base of the goal forecast.
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In the diary I work out all of these numbers myself — you just log the set.