Dynamic Strength Index (DSI) Calculator

What Is the Dynamic Strength Index?

The Dynamic Strength Index (DSI), also called the Dynamic Strength Deficit or Explosive Strength Deficit, is a ratio comparing an athlete's ballistic peak force to their maximal isometric peak force. It quantifies how much of an individual's total force capacity is being utilized during high-speed dynamic movements.

Commonly, ballistic peak force is measured during a Countermovement Jump (CMJ) and isometric peak force during an Isometric Mid-Thigh Pull (IMTP), both using force plate technology.

Interpreting DSI Values

• DSI < 0.60 — Ballistic emphasis: The individual may benefit from more explosive/ballistic training, as they are only expressing less than 60% of their maximal force capacity during dynamic movements.
• DSI 0.60–0.80 — Concurrent: A balanced training approach blending strength and explosive work is suggested.
• DSI > 0.80 — Strength emphasis: The individual may benefit from increasing their maximal strength ceiling, as they are already expressing a large proportion of their force capacity dynamically.

These thresholds originate from Sheppard et al. (2011) and have been widely adopted in strength and conditioning practice (Suchomel et al. 2020).

Testing Methodology

For the most valid DSI assessment, use one ballistic test and one isometric test measured on a force plate. Common pairings include CMJ + IMTP, Squat Jump + IMTP, or CMJ + Isometric Squat. Ensure consistent warm-up protocols and at least 3 trials per test, using the best trial for each.

For related strength assessments, see our One Rep Max Calculator and Two Rep Max Calculator.

How to Use This Calculator

1. Enter your ballistic peak force in Newtons (from a CMJ or similar test)
2. Enter your isometric peak force in Newtons (from an IMTP or similar test)
3. Optionally enter body weight for normalized force values (N/kg)
4. Click "Calculate DSI" to see your ratio, classification, and training emphasis
5. Compare against the sport benchmark table for context

Related tools: Vertical Jump Calculator, Relative Strength Calculator