What this calculator does
It turns one number, the weight of your first working set, into the sets that get you there. Light enough to groove the movement, heavy enough that the first working set is not a shock, few enough that you arrive fresh. The loads are rounded to plates you can put on the bar, which is what most warm-up calculators skip and why their numbers end in .3.
It is for barbell and dumbbell lifts where the working weight is meaningfully heavier than the bar. For a 20 kg overhead press the ramp is one set with the bar, and the calculator says so by returning fewer rows.
A worked example
Back squat, first working set at 100 kg (220 lb), a 20 kg bar.
| Set | Load | Reps | Why |
|---|---|---|---|
| 1 | 20 kg, the bar | 10 | Pattern and range, no load |
| 2 | 40 kg | 6 | 40%: still light, speed up |
| 3 | 60 kg | 4 | 60%: the bar starts to feel like something |
| 4 | 80 kg | 2 | 80%: rehearsal of the working weight |
| 5 | 90 kg | 1 | 90%: one heavy single, so 100 feels normal |
| Work | 100 kg | as planned |
At 60 kg the same lift gets three warm-up sets, not five: the bar, 35 kg and 47.5 kg. The 90% single appears only above 100 kg, where the gap between the last warm-up and the working set is wide enough to matter.
Why reps fall as the weight rises
Early warm-up sets are about the movement: ten easy reps with the bar wake up the pattern and the range of motion. Later sets are about the nervous system: a double at 80% and a single at 90% prime the muscle for the load without spending the energy you need for the working sets. Doing eight reps at 80% is not a warm-up; it is a working set you did not plan.
The evidence agrees with coaching habit here. A 2024 trial that compared a heavy conditioning set (three reps at 90% of 1RM) with light warm-ups before squats to failure found more volume on the first working set after the heavy set, and no difference across the whole session (Souza et al., PeerJ). The heavy single buys you a better first set, which is the set that counts most for progression; it costs nothing later if it stays a single.
Rounding to real plates
A bar loads in 2.5 kg steps with 1.25 kg plates, or 5 lb steps with 2.5 lb plates. Most dumbbell racks go up in 2 kg or 5 lb. Machine stacks move in 5 kg or 10 lb pins. The calculator rounds every set to the nearest step the equipment can make and never rounds below the bar. When two steps round onto the same weight, one is dropped, which is why a light working weight produces a short ramp.
Limits of this tool
- It knows the working weight, not how you feel. A cold gym or a long day earns one extra light set; add it.
- It is one ramp per exercise. The second exercise of a session that uses the same muscles needs less: usually one set at 60% and one at 80%.
- Isolation lifts and most machines need a single warm-up set. The calculator returns a ramp anyway; use the last row.
- It does not program the general warm-up: five minutes of easy movement before the first bar set still belongs to you.
What BurnX does with this
In the app the session screen shows your working weight for the day, decided the Monday before from what you lifted. The warm-up ramp is yours to run; this calculator is the same arithmetic on a page, so you can use it for any program.