Free Tool
Lombardi 1RM Calculator
Calculate your one rep max using the Lombardi formula. Enter weight and reps for a conservative 1RM estimate.
1RM formulas are most accurate for 1–10 reps. Results above 15 reps become less reliable.
The Lombardi formula
The Lombardi formula, introduced by V.H. Lombardi in 1989, uses an exponential relationship between reps and 1RM:
1RM = weight × reps^0.10
Example: 225 lbs × 5 reps → 1RM = 225 × 5^0.10 = 225 × 1.174 = 264.2 lbs
The exponent of 0.10 means that each doubling of reps increases the implied 1RM by roughly 7%. Compared to Epley and Brzycki, Lombardi tends to produce the most conservative estimates at moderate to high rep ranges, making it a useful sanity check against the other formulas. Some research suggests it performs particularly well for intermediate lifters performing 4–8 rep sets on compound barbell movements.
One practical advantage of the Lombardi formula is its mathematical simplicity for mental estimates — a set of 10 reps implies a 1RM of roughly 1.26× the training weight (10^0.10 ≈ 1.259), which is easy to approximate in your head.
Compare other methods
The Epley formula is the most widely cited 1RM equation. The Brzycki formula is favored by strength coaches for its conservative estimates at low rep ranges. To see all three formulas side by side and get an averaged estimate, use the main 1RM calculator.
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