Solow–Swan Growth Model

Long-run dynamics of income per worker. Move the controls: the initial situation is dashed, the current one is solid, the arrows show what changed, and the charts below show the transition over time. Hover over the charts (or drag a finger across them) to read the values.

Solow diagram

f(k) = A·kα (output) s·f(k) (investment) (n+g+δ)·k (break-even investment) initial situation E* steady state Golden Rule

Transition over time

Golden Rule

Equations: y = A·kα · Δk = s·f(k) − (n+g+δ)·k · k* = (s·A/(n+g+δ))1/(1−α) · c* = (1−s)·y* · Golden Rule: f'(k) = n+g+δ, i.e., s = α · speed of convergence λ = (1−α)(n+g+δ). With g > 0, k, y, and c are measured per effective worker (K/EL), and output per worker Y/L grows at rate g in the long run. The time path uses the exact solution of the Solow equation.