How to measure any spring

Below is a guide on how to measure common types of springs, suitable for engineering, purchasing, or replacement purposes.

Before measuring any spring:

• Measure in a relaxed state
• Use callipers, rulers alone are not accurate enough
• Record measurements in millimetres (mm)
• Avoid stretching or compressing the spring during measurement
• Count active coils only (Count the number of 360 revolutions that are separated by a space and not touching)

Compression Springs

How to Measure

1. Free Length / Overall Length

   • Measure overall length from end to end with no load applied.

2. Outside Diameter (OD)

   • Measure across the widest point of the coils.

3. Wire Diameter 

   • Measure wire thickness using callipers.

4. Inside Diameter (ID)

   • Calculate from OD and wire diameter.

5. Number of Active Coils

   • Count only coils that deflect under load. (Count the number of 360 revolutions that are separated by a space and not touching)

6. End Type

   • Note whether ends are:

     • Closed
     • Open
     • Ground
     • Closed and ground

Optional (if required):

• Spring rate (N/mm) measured using compression force testing equipment.

Tension / Extension Springs

How to Measure

1. Free Length

   • Measure from inside face of one hook to inside face of the other, with no load.

2. Body Length

   • Measure the coil-only section, excluding hooks.

3. Wire Diameter

   • Measure one coil with callipers.

4. Outside Diameter (OD)

   • Measure across coils along the main body, excluding hooks.

5. Hook Style and Orientation

   • Identify:

     • Machine hook
     • Crossover hook
     • Extended hook
     • Hook angle and direction

Optional:

• Initial tension (requires force test equipment)

Torsion Springs

Torsion springs store energy by twisting.

How to Measure

1. Inside Diameter (ID)

   • Measure the internal coil diameter directly.

2. Wire Diameter

   • Measure wire thickness with callipers.

3. Leg Lengths

   • Measure each leg from coil centreline to leg end.

4. Leg Orientation

   • Clockwise or counter‑clockwise
   • Measure the angle between legs (degrees)

5. Number of Coils

   • Count total coils (torsion springs typically use all coils).

Optional:

• Torque rate (Nm/degree) using a torsion test rig.

Measurement Tips 

• If tolerances are tight and / or copying an existing spring, feel free to send a sample to our listed address Contact Us
• Measure multiple points and average if tolerances are tight
• Take photos of springs with labels or orientation notes

•  record:

  • Application
  • Operating load
  • Travel distance

Direct sales email contact:
accounts@tensionworks.com.au