TaskJunction

Tension Spring Calculator

Tension spring rate, initial tension, stress, and extension under load.

Calculate spring rate, deflection beyond initial tension, and shear stress for a helical extension spring.

Tension (Extension) Spring Calculator

Inputs

Results

Spring Index (C)
8.00
Wahl Correction Factor
1.184
Max Shear Stress
385.9MPa
Spring Rate (k)
4.03N/mm
Deflection Beyond Preload
19.83mm
Factor of Safety
1.30
Body Length (approx, excl. hooks)
32.5mm

Formula Used

Same as compression spring, but deflection δ = (P - Pi)/k for P > Pi
Hook/loop end stress concentration is often the actual failure point in extension springs — this calculator covers body coil stress only. Verify hook design separately for critical applications.

⚠ For preliminary design and educational use only. Verify all results against applicable codes and standards before use in production or safety-critical applications.

About this calculator

Part of our Mechanical Calculators collection. Beams, bolts, springs, gears, bearings, and core ME calculations.

How it works

Calculates helical tension spring stiffness, initial tension, corrected shear stress, and total extension under applied load.

Enter your values in the inputs above and click CALCULATE. Results appear on the right without a page reload. No login and no server upload.

Privacy and accuracy

Every calculation runs locally in your browser. Your design data never leaves your device. Results are intended for preliminary engineering work. Always verify critical designs with qualified review and applicable standards before production use.

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