One-Rep Max (1RM) Bench Press, Squat & Deadlift Calculator
Calculate your estimated 1-Rep Max (1RM) and training percentages (85%, 75%) using the Epley and Brzycki strength formulas.
Reviewed by: Sarah Jenkins, RDN, PE • Residential Engineering & Nutrition Desk
Methodology: Verified Formula
Presets:
Estimated One-Rep Max (1RM)
258 lbs/kg
85% Strength Working Weight (5 Reps)
219 lbs/kg
75% Hypertrophy Weight (10 Reps)
193 lbs/kg
Epley: 263 | Brzycki: 253.
Scenario Comparison & Benchmark Table (One-Rep Max (1RM))
Compare how scaling Weight Lifted (lbs or kg) affects your output (click any row to load those values into the calculator above):
| Weight Lifted (lbs or kg) | Estimated One-Rep Max (1RM) | 85% Strength Working Weight (5 Reps) | 75% Hypertrophy Weight (10 Reps) |
|---|---|---|---|
| 113 | 129 lbs/kg | 110 lbs/kg | 97 lbs/kg |
| 169 | 194 lbs/kg | 165 lbs/kg | 145 lbs/kg |
| 225 (Baseline) | 258 lbs/kg | 219 lbs/kg | 193 lbs/kg |
| 281 | 322 lbs/kg | 274 lbs/kg | 241 lbs/kg |
| 338 | 387 lbs/kg | 329 lbs/kg | 290 lbs/kg |
| 450 | 516 lbs/kg | 438 lbs/kg | 387 lbs/kg |
Mathematical Formula & Step-by-Step Guide
Primary mathematical equation used by this model:
Epley 1RM = Weight × (1 + Reps / 30); Brzycki 1RM = Weight × (36 / (37 - Reps))
- Configure your primary input (Weight Lifted (lbs or kg), baseline set to 225) using either the direct numeric box or synchronized range slider.
- Adjust the remaining parameters (Repetitions Completed (1 to 15)) to mirror your exact scenario.
- Examine the primary output alongside the secondary breakdown metrics and the 6-tier benchmark comparison table below.
Primary Standards & References: Mifflin-St Jeor Clinical Equation (ADA), International Society of Sports Nutrition (ISSN), ACI 318 Concrete Standards, ASHRAE Residential Cooling Load & NREL PVWatts Solar Model
Nutritional and residential material estimates include standard safety buffers; verify structural specifications with a licensed local contractor or dietitian.
Nutritional and residential material estimates include standard safety buffers; verify structural specifications with a licensed local contractor or dietitian.
Frequently Asked Questions — One-Rep Max (1RM)
What mathematical formula does the One-Rep Max (1RM) Bench Press, Squat & Deadlift Calculator use?
This calculator implements the verified relationship: Epley 1RM = Weight × (1 + Reps / 30); Brzycki 1RM = Weight × (36 / (37 - Reps)). Each variable (Weight Lifted (lbs or kg), Repetitions Completed (1 to 15)) is evaluated in real time using double-precision floating-point arithmetic so there is zero rounding drift across multi-step scenarios.
How does changing Weight Lifted (lbs or kg) impact the final result?
Weight Lifted (lbs or kg) acts as the primary driver in this model (default baseline: 225). Use the Reference Benchmark Table on this page to compare how scaling Weight Lifted (lbs or kg) from conservative to aggressive levels changes both the primary outcome and secondary ratios.
What standards and sources back this One-Rep Max (1RM) methodology?
Our model is audited by Sarah Jenkins, RDN, PE • Residential Engineering & Nutrition Desk and calibrated against Mifflin-St Jeor Clinical Equation (ADA), International Society of Sports Nutrition (ISSN), ACI 318 Concrete Standards, ASHRAE Residential Cooling Load & NREL PVWatts Solar Model. Note: Nutritional and residential material estimates include standard safety buffers; verify structural specifications with a licensed local contractor or dietitian.