Hamstring/Quadriceps Ratio Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/9/2026
The hamstring/quadriceps ratio is calculated by dividing hamstring strength by quadriceps strength, expressed as a percentage. For 40 kg tested on the hamstrings and 65 kg on the quadriceps, the ratio is about 61.5%, within the usual 50-80% range.
Explanation
The hamstring/quadriceps ratio (H:Q ratio) compares the strength of the muscles at the back of the thigh to that of the quadriceps at the front. These two muscle groups often act in opposition around the knee, and a pronounced imbalance between them is studied in sports medicine as a potential injury risk factor, notably to the hamstrings or the anterior cruciate ligament (ACL), particularly in sports with sudden changes of direction. The so-called "conventional" ratio (concentric hamstring strength divided by quadriceps strength, measured at a comparable test speed) generally falls between 50% and 80% in an active person, with a value around 60% being the most commonly cited benchmark for balance; below 50%, this is sometimes called "quadriceps dominance." **However, there is no precise, universally validated threshold**: scientific reviews on the topic themselves point out the lack of consensus on a threshold value that would reliably predict injury, with the functional ratio (eccentric/concentric) and other individual factors also playing a role. Like the push/pull ratio for the upper body, this ratio remains a directional indicator to interpret with caution, not a diagnosis.
Example for a strength test at the gym
Inputs
Hamstring strength: 40 kg. Quadriceps strength: 65 kg.
Calculation
Ratio = (40 ÷ 65) × 100 ≈ 61.5%.
Result
The ratio is about 61.5%, within the usual 50-80% range considered balanced.
Frequently asked questions
What does a ratio below 50% mean?
A ratio below 50% is sometimes called "quadriceps dominance": the hamstrings appear relatively weak compared with the quadriceps. This can justify targeted hamstring strengthening work, particularly in sports involving sprints or changes of direction.
How do you measure hamstring and quadriceps strength?
In common practice, a maximum load tested on guided machines (leg curl for the hamstrings, leg extension for the quadriceps) gives a usable estimate for this ratio, on the same principle as our strength-to-weight ratio calculator. A professional setting (isokinetic dynamometer) offers a more precise measurement, especially in a rehabilitation context.
Does a ratio within the usual range guarantee no injury risk?
No. This ratio is one indicator among others, with no threshold universally validated by research to reliably predict injury. Technique, injury history, flexibility, and overall training load also play an important role.