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Lift Forecast: how much stronger will you be in 12 weeks?
A strength progression calculator. Enter one set you have done and how long you have been training. You get a realistic range for the same set in 6, 12 or 24 weeks, with the date it lands, from published rates of strength gain rather than a guess.
The same set, week by week
Two of Mesolab's 6-week blocks: volume climbs for five weeks, then a deload in weeks 6 and 12. The range for each week is the same set at the end of that week; strength gains slow as the weeks go on, so the early weeks move more than the late ones.
| Week | Ends | 5 reps at 2 RIR | What the week is |
|---|---|---|---|
| Week 1 | Tue, Oct 20 | 185–187.5 lb | Starting volume |
| Week 2 | Tue, Oct 27 | 187.5–190 lb | Up to one more set per exercise |
| Week 3 | Tue, Nov 3 | 187.5–190 lb | Up to one more set per exercise |
| Week 4 | Tue, Nov 10 | 187.5–192.5 lb | Up to one more set per exercise |
| Week 5 | Tue, Nov 17 | 187.5–195 lb | Up to one more set per exercise |
| Week 6 | Tue, Nov 24 | 190–195 lb | Deload: fewer sets, lighter weights |
| Week 7 | Tue, Dec 1 | 190–197.5 lb | Up to one more set per exercise |
| Week 8 | Tue, Dec 8 | 190–197.5 lb | Up to one more set per exercise |
| Week 9 | Tue, Dec 15 | 190–200 lb | Up to one more set per exercise |
| Week 10 | Tue, Dec 22 | 192.5–200 lb | Up to one more set per exercise |
| Week 11 | Tue, Dec 29 | 192.5–202.5 lb | Up to one more set per exercise |
| Week 12 | Tue, Jan 5 | 192.5–202.5 lb | Deload: fewer sets, lighter weights |
Want the block itself, with exercises, sets and RIR for every week? The free mesocycle generator builds it from the same planner as the app.
Hit the number: train the 12 weeks in Mesolab
The iPhone app plans the block, suggests a weight for every set from your own logged sets and reps in reserve, and shows week by week whether you are on the line. Free to download; your first completed workout is free.
How fast can you get stronger? Realistic gains by training age
Strength goes up fast at first and then slows, and it keeps slowing for as long as you train. Across every large dataset that has been fitted, the curve is the same shape: gains are roughly linear in the logarithm of time. Each equal step up takes about twice as long as the one before. That is why the first question the forecast asks is how long you have trained, and why its answer is a range.
| Training this lift for | 6 weeks | 12 weeks | 24 weeks | Where it comes from |
|---|---|---|---|---|
| Under a year | +7 to +19% | +12 to +33% | +19 to +52% | Untrained men benching three days a week went from 51 kg to 77 kg in 24 weeks (Ogasawara 2013); 14,690 gym members on one session a week gained 30–50% in year one (Steele 2022) |
| 1 to 3 years | +2 to +6% | +4 to +10% | +6 to +16% | Interpolated between the other two bands; no controlled study of this group reports 12-week 1RM change, so the band is wide on purpose |
| Over 3 years | +1 to +2% | +1.5 to +4% | +2 to +6% | 1,897 powerlifters added about 0.15 kg a day to their totals over 15 years, roughly 4 kg per lift per 12 weeks (Latella 2020); first-year competitors gain 7.5–12.5% (Latella & Steele); experienced lifters call +2% per lift in six weeks a meaningful gain (Androulakis-Korakakis 2021) |
The squat tends to move faster than the bench press for the same lifter, and the deadlift sits between. The ranges above are not adjusted for the lift, so read a squat forecast toward its top and a bench forecast toward its middle.
How the strength progression calculator works
- Your set becomes an estimated 1RM. Weight × (1 + (reps + RIR) ÷ 30): the Epley formula over effective reps, the same formula the Mesolab app and the RIR calculator use. 185 lb × 5 at 2 RIR is about 228 lb.
- The published range for your training age is applied to that 1RM. 12 weeks is the band's full range; 6 weeks gets 58% of it and 24 weeks 158%, following the log curve above.
- The future 1RM converts back to your set. The same reps and RIR, so the number on the card is a weight you can test on the day, rounded to 2.5 lb or 1.25 kg.
- The date is today plus the weeks. Put it in your calendar. The week-by-week table shows what the same set looks like along the way, with the app's deload in weeks 6 and 12.
Common questions
How much should my bench press go up in 12 weeks?
For a lifter one to three years in, the published band is 4–10% on estimated 1RM. On a 225 lb bench that is 9–22 lb; on a 100 kg bench, 4–10 kg. In the first year it is far more (12–33%), and after three years far less (1.5–4%). Enter your own set above for the number in your units.
Is 5 lb a week a realistic strength gain?
Only early on. 5 lb a week is 60 lb in 12 weeks, which is a 27% gain on a 225 lb lift: inside the first-year band, above the top of every later band. Beginners can add weight almost every session; after a year, most lifters add a few pounds a month to their best sets and do it in blocks, with deloads.
Why a range and not one number?
Because the studies report one. The spread between lifters on the same program is larger than the average gain. The low end is what a planned block tends to deliver; the top needs food, sleep and no missed weeks.
What counts as "under a year" of training?
Time spent training this lift on a program, not time since you first walked into a gym. If you benched now and then for five years and started a real program in March, you are under a year.
Does the forecast change by lift?
Not yet. The bands apply to any lift. Squats tend to progress faster than bench presses for the same person, so read a squat forecast toward its top.
How do I actually hit the number?
Train the lift two or three times a week in a block that adds sets week to week and deloads, keep reps in reserve honest, and test the same set on the date. The mesocycle generator plans the block; the suggested weight guide explains how the app picks each session's weight.
Is this calculator free?
Yes. No account and nothing is stored. The link copies your inputs so you can share the forecast or come back to it on the date.