Build an Estimated 1RM Trend from WHOOP Logs
WHOOP Strength Trainer records your sets. It does not calculate an estimated one-rep max, which means the single most useful number for tracking progress is one multiplication away from what you already have — and you have to do that multiplication yourself.
The short answer
Take your best set per lift per session and apply 1RM = weight × (1 + reps ÷ 30). Plot that number against date and you have a progression line instead of a list of weights. The whole process is a formula and a spreadsheet, and it's the difference between a session logger and a progress tracker.
Why you need a derived number at all
Logged weight on its own is a poor progression measure, and it fails in a specific, predictable way. Look at these three sessions of the same lift:
Session B 90 kg × 4
Session C 85 kg × 8
By weight, Session B looks like the best session — 90 kg is the heaviest number on the page. By capacity, it is very nearly the worst. The problem is that comparing loads across different rep counts is meaningless: 90 kg for 4 is a fundamentally different achievement from 85 kg for 8, and neither can be compared to the other without normalising.
The estimated one-rep max does that normalisation by projecting every set to an equivalent single. Once applied, the ordering changes completely — and Session C turns out to be the best of the three despite never touching 90 kg. That reordering is invisible if you only ever look at the weight you lifted.
The method, step by step
- Pick one main lift to start with. Bench press, squat or deadlift. Don't try to build trends for every movement in your programme on day one — you will not maintain it.
- For each session, find your best set for that lift. Best means highest estimated 1RM, not heaviest. A moderate set of 10 can beat a heavy set of 3.
- Apply the formula.
weight × (1 + reps ÷ 30). The 1RM calculator does this for you with six formulas if you want to compare. - Record the result against the date. Date, exercise, weight, reps, estimated max. One row per session.
- Plot it and stop looking at daily values. Single sessions are mostly noise. Read the line, not the points.
- Compare in blocks of three. Mean estimated max over your last three sessions against the three before that. A single session tells you almost nothing; three is the smallest unit that means something.
Worked example, to show the arithmetic rather than to present a result:
- Week 1, best set 80 kg × 8 → 80 × (1 + 8/30) = 101 kg
- Week 2, best set 80 kg × 8 → 101 kg
- Week 3, best set 85 kg × 6 → 85 × (1 + 6/30) = 102 kg
- Week 4, best set 85 kg × 8 → 85 × (1 + 8/30) = 108 kg
Those are four made-up numbers to demonstrate the calculation. Your own figures will be different, and they are the only ones that matter. What the example shows is the shape of the signal: weeks one and two are indistinguishable, week three is barely a change, and week four is a real move that a weight-only view would have shown as "85 kg, same as last week".
Choosing a formula, and why it matters less than you think
Several one-rep max formulas are in use. They agree closely at low rep counts and diverge as reps climb:
| Formula | Shape | Behaviour at high reps |
|---|---|---|
| Epley | w × (1 + r/30) | Least conservative of the common ones |
| Brzycki | w × 36 / (37 − r) | More conservative than Epley |
| Lombardi | w × r^0.10 | More conservative still |
| O'Conner | w × (1 + 0.025r) | Comparatively flat across rep range |
Pick one and stay with it. Switching formulas mid-series invalidates your trend, because the apparent jump will be the formula change rather than your training. This matters more than which formula you choose — a consistent O'Conner series is far more useful than a series that alternates between Epley and Brzycki.
Where estimates stop being reliable
Estimated 1RM is trustworthy in roughly the 2–10 rep range and progressively less so beyond it, because the relationship between load and fatigue stops being linear at higher rep counts. A 20-rep estimate is not comparable to a 3-rep estimate even though the arithmetic produces both. For trend purposes, prefer your mid-range sets and ignore the outliers at either end.
How much history you actually need
Four to six weeks of consistent logging on a lift is usually enough to see a direction rather than noise. To be explicit about provenance: that is a practical convention, not a published threshold. It reflects roughly when session-to-session variability stops dominating the trend — not a statistical guarantee, and not a finding we can cite to a study.
The limiting factor is logging consistency, not sample size. Six weeks of complete logs is more useful than six months of partial ones, because a gap in the series makes the trend harder to read than a shorter clean one. Do not abandon the habit because you missed a week — just continue.
Once you have the line, the next question is whether it's moving. A trend that holds the same weight for weeks looks identical whether you are improving or stalling. How to spot a lifting plateau covers how to tell the difference.
Frequently asked
How do I calculate an estimated 1RM from WHOOP Strength Trainer logs?
Take your best set per lift per session and apply a formula. The common one is Epley: 1RM = weight × (1 + reps / 30). So 80 kg for 8 reps gives about 101 kg estimated. Plot that per session and you have a trend line rather than a list of weights.
Which one-rep max formula should I use?
They agree closely in the 1–6 rep range and diverge as reps climb. Epley is the most commonly cited and the easiest to remember; Brzycki is more conservative, Lombardi less so. The choice matters far less than consistency — switching formulas mid-series invalidates your trend.
Is an estimated 1RM accurate?
Reasonably so in roughly the 2–10 rep range, and progressively less so beyond it, because the relationship between load and fatigue stops being linear at higher rep counts. Treat a 20-rep estimate as a rough indicator rather than a comparable number.
How many sessions do I need before a 1RM trend is meaningful?
Four to six weeks of consistent logging on a given lift is usually enough to see a direction rather than noise. This is a practical convention rather than a published threshold — it reflects when session-to-session variability stops dominating the trend.
Should I use my heaviest set or my best set for estimated 1RM?
Your best estimated figure, not necessarily your heaviest set. A heavy set of 3 and a moderate set of 10 can produce different estimated maxes, and the higher estimate better reflects capacity. This is why raw logged weight alone is a poor progression measure.
Related
- Estimated 1RM calculator — six formulas, free
- Tracking strength progression on WHOOP — what the app records and what it leaves to you
- Peak Load vs estimated 1RM vs Top Set Output
- How to spot a lifting plateau in your data
Sources
- WHOOP Strength Trainer support documentation — support.whoop.com
- Epley, B. (1990). Weightlifting predictors of one-rep max performance: a review. Journal of Strength and Conditioning Research.
- Brzycki, Z. (1990). Accuracy of predicted and measured maximal one-rep lift. Journal of Strength and Conditioning Research.