Calculators
Series and Parallel Spring Calculator
Calculate equivalent spring stiffness for ideal linear springs in series or parallel, with N/m, N/mm, and kN/m units.
Enter 1–1000 positive spring constants in one unit, separated by commas, semicolons, spaces, or newlines. Use values from 1e-12 to 1e12. Changing the unit reinterprets the numbers.
Assumes ideal linear springs within their elastic limits. Series springs carry the same force; parallel springs share the same displacement. Excludes preload, damping, and mixed networks.
Combine spring constants in series or parallel.
For ideal linear springs, series stiffness follows 1/k = 1/k₁ + 1/k₂ + … + 1/kₙ, because each spring carries the same force and displacements add. Parallel stiffness is k = k₁ + k₂ + … + kₙ, because each spring undergoes the same displacement and forces add. For 10, 20, and 30 N/m, series stiffness is approximately 5.45454545455 N/m and parallel stiffness is 60 N/m. Series stiffness is at most the smallest input; parallel stiffness is at least the largest. A single spring returns its own stiffness. Enter 1–1000 positive spring constants between 1e-12 and 1e12 in one selected unit. Changing the unit reinterprets the values rather than converting them. This model assumes ideal linear axial springs within their elastic limits and excludes preload, damping, nonlinear behavior, and mixed networks. Results display up to 12 significant digits locally in your browser.
Frequently Asked Questions
Everything you need to know about this tool, how it works, and privacy.
How do springs combine in series and parallel?
Series springs carry the same force: 1/k = Σ(1/kᵢ). Parallel springs share the same displacement: k = Σkᵢ. Two 100 N/m springs give 50 N/m in series or 200 N/m in parallel.
Which units can I use?
Use one unit for all inputs: N/m, N/mm, or kN/m. One N/mm or kN/m equals 1000 N/m. Changing the selection reinterprets your numbers; convert mixed inputs to a common unit first.
Which inputs are supported?
Enter 1–1000 positive spring constants from 1e-12 to 1e12 in the selected unit, separated by commas, spaces, semicolons, or newlines. Scientific notation is accepted. Zero and negative stiffness values are excluded.
When is this model appropriate?
Use ideal linear axial springs within their elastic limits, with the same force in series or the same displacement in parallel. Preload, damping, nonlinear springs, and mixed networks require additional modeling. Inputs and calculations remain in your browser.