Stock and Flow Equilibrium Calculator
Calculate the equilibrium stock level where inflow equals outflow, time to reach equilibrium, and analyze stock dynamics using system dynamics principles.
units
units/period
fraction/period (0–1)
periods
Formulas
Equilibrium Stock: S* = I / f
Analytical Stock Path: S(t) = S* + (S₀ − S*) · e−f·t
Discrete Recursion: S(t+1) = S(t) · (1 − f) + I
Time Constant (Avg Residence Time): τ = 1 / f
Half-life to Equilibrium: t½ = ln(2) / f ≈ 0.693 / f
Gap Closed after T periods: (S(T) − S₀) / (S* − S₀) × 100%
Assumptions & References
- References: Forrester, J.W. (1961) Industrial Dynamics; Sterman, J.D. (2000) Business Dynamics, MIT Press.