Deadlift 1RM math is identical to bench — variance isn't
The four prediction formulas don't care which lift you're doing. Epley, Brzycki, Lombardi, and O'Conner each fit a curve to load-vs-reps; a 140 kg × 5 deadlift and a 140 kg × 5 bench produce numerically identical 1RM estimates. The LeSuer 1997 reliability bands also apply identically (±2% at ≤5 reps, widening past that).
What changes is real-world variance. Deadlift is more condition-sensitive than bench: stance (conventional vs sumo), grip (double-overhand vs hook vs mixed vs strapped), bar height (deficit vs floor vs block), rep style (dead-stop vs touch-and-go), and equipment (belted vs raw) all materially shift what the same load actually means. The math returns one number; honest reporting needs the conditions attached.
A worked example — 180 kg × 3 deadlift
Run 180 kg × 3 reps on conventional deadlift, dead-stop, mixed grip. Same four-formula math:
- Epley: 180 × (1 + 3/30) = 198.0 kg
- Brzycki: 180 × 36 / (37 − 3) ≈ 190.6 kg
- Lombardi: 180 × 3^0.1 ≈ 200.9 kg
- O'Conner: 180 × (1 + 3 × 0.025) = 193.5 kg
Cross-formula average ≈ 195.8 kg deadlift 1RM with a HIGH reliability band of ±2% (~191.9–199.7 kg). The spread of ~10 kg across formulas at 3 reps is normal; the average is the honest take-home.
Cross-check against squat: if back-squat 1RM is ~155 kg, the deadlift:squat ratio is ~1.26 — squarely in the typical 1.0–1.3× range for intermediate and advanced lifters. A ratio under 1.0 usually points at a posterior-chain volume gap or a grip bottleneck; a ratio above 1.3 typically reflects long-armed anthropometry or extensive deadlift-focused programming. For programming weights off this number, the percentage-of-1RM calculator surfaces both NSCA traditional and ACSM 2026 bands.
Frequently asked
Is conventional deadlift 1RM the same as sumo 1RM?
No. The math is the same — formula × submax-rep input — but conventional and sumo are different lifts. Most lifters pull 5–15% more in their stronger style; which side that is depends on hip structure, anthropometry (limb length / torso ratio), and training history. Long-femured lifters tend to favor sumo; short-femured lifters tend to favor conventional. Estimate from whichever style you trained — don't try to predict your sumo pull from a conventional set, or vice versa.
How does grip affect the 1RM estimate?
It doesn't enter the math, but it caps the lift. Double-overhand grip typically tops out around 60–70% of mixed-grip or hook-grip max because the bar rolls out of the fingers before the legs and hips run out. If your submax set was double-overhand and you're estimating a max you'd attempt mixed-grip, the estimate will under-predict by 30–40%. The fix: use straps or hook for high-rep submax work to remove grip as the limiter, then estimate from that load. Or accept that the headline number is a 'double-overhand 1RM' specifically, which is a useful tracked metric in its own right.
What rep range gives the most reliable deadlift 1RM estimate?
≤5 reps is the HIGH reliability band (~±2%) per LeSuer 1997. 6–10 reps is MEDIUM (~±5%). Past 10 reps is genuinely noisy — and deadlift is more rep-noisy than bench or squat because back fatigue accumulates fast across high-rep sets and form degrades non-linearly. A 10-rep deadlift set ending with a rounded back is a different lift than a 10-rep set with neutral spine throughout, and the formulas can't see that. Most experienced lifters cap their 1RM-estimation work at 5 reps for this reason.
Should I estimate from a touch-and-go or dead-stop set?
Dead-stop is the more honest input. Touch-and-go reps reuse stretch reflex from the eccentric, which adds typically 5–10% to the load you can move per rep. A touch-and-go set of 5 estimates an inflated 1RM compared to what you'd actually pull off the floor cold. If you trained touch-and-go, label the resulting estimate as 'touch-and-go 1RM' — it's not the same metric as a true 1RM attempt where every rep starts from the floor with no rebound.
Why does my deadlift 1RM look so much higher than my squat 1RM?
Because for most lifters, it should. Deadlift typically lands at 1.0–1.3× back squat for intermediate and advanced lifters — the lever arms favor deadlift slightly (no eccentric pre-loaded), and the deadlift involves more total muscle mass through the posterior chain. Lifters with shorter arms and longer femurs sometimes anchor closer to 1.0×, while long-armed lifters often run 1.2× or higher. If your deadlift is below your squat, it's usually a programming-volume gap or a grip-strength bottleneck, not weak hips.
What I'd do next
- Estimate squat 1RM separately
Don't infer squat from deadlift. The 1.0–1.3× ratio is a population observation, not a conversion factor for any individual lifter.
- Build deadlift working weights
Same %1RM table, applied to your deadlift number. Surfaces both NSCA traditional and ACSM 2026 bands.
- Pick a grip for max attempts
Hook vs mixed vs strap — the tradeoffs that decide whether your max-attempt grip caps the lift.
By Jimmy L Wu. Engine shared with the general 1RM calculator — same four published formulas (Epley 1985, Brzycki 1993, Lombardi 1989, O'Conner et al. 1989), same LeSuer 1997-grounded reliability bands. Deadlift-variant ratios (sumo:conventional ±5–15%, touch-and-go:dead-stop +5–10%, double-overhand cap ~60–70% of mixed or hook, deadlift:squat 1.0–1.3× typical) are training-population observations, not conversion factors — track your own ratios over time rather than calculating off published averages. Engine logic in lib/strength/oneRepMax.ts. Not medical advice — for max attempts, work with a qualified strength coach.