Training load calculator
Enter up to five of your lifts. You'll get the weight to use in every muscle-building rep range at 1 rep in reserve — plus a double progression plan built for how long you've been training.
Your lifts
Unit
For each lift, use a set you took to roughly one rep short of failure, 15 reps or fewer. The closer to failure it was, the closer these numbers land.
What you get — an example
Hack squat
example
Estimated 1RM
0kg
Estimates — adjust to how the set actually feels.
What the science actually says
- Mechanical tension is the driver
- Muscle growth is primarily caused by high mechanical tension on the muscle fibres — not by reps, sets, or the exact load on the bar.
- Proximity to failure beats rep range
- Training close to failure (0–3 RIR) recruits high-threshold motor units and matters more than whether you do 6 or 16 reps.
- Any sensible rep range works
- Roughly 5–30 reps per set builds muscle when taken close to failure. However lower rep ranges will give you the most stimulus without accumulating too much fatigue. Ultimately use the range that fits the exercise and your recovery.
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