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When a standard spring is too large, too stiff, or simply unavailable at your local hardware store, finding the right miniature compression spring becomes a real obstacle. Whether you are a hobbyist repairing a mechanical pen, an engineer prototyping a sensor assembly, or a technician servicing small appliances, these small-diameter coil springs give you the exact tension and travel you need without over-engineering the solution.
Each pack contains 10 pieces (5 pieces for lengths 60mm and above) of steel compression springs. Wire diameter options span 0.3 mm, 0.4 mm, and 0.5 mm. Outer diameter (OD) ranges from 2 mm to 10 mm (approximately 0.08 in to 0.39 in). Free length options run from 5 mm to 100 mm (approximately 0.20 in to 3.94 in), covering a wide range of travel requirements in a single product listing.
Typical use cases include spring-loaded button mechanisms in consumer electronics, return springs in miniature valves and actuators, compression elements in pen and stylus assemblies, and load-bearing spacers in precision jigs and fixtures. Long-tail applications such as "small OD compression spring for electronics repair" and "miniature steel coil spring for DIY projects" are well served by this range.
Wire diameters of 0.3 mm, 0.4 mm, and 0.5 mm combined with OD options from 2 mm to 10 mm and lengths from 5 mm to 100 mm give you precise control over spring rate and travel distance.
Made from steel wire, these springs deliver consistent elastic return force and resist permanent set under repeated compression cycles typical of light-duty mechanical applications.
Each order ships 10 pieces (5 pieces for 60 mm+ lengths), giving you spares for prototyping, testing, or replacing worn components without reordering immediately.
Small OD springs require consistent coil pitch and wire diameter to function correctly in confined bores. These springs are wound to maintain dimensional consistency across the pack.
From pen mechanisms and button returns to miniature actuators and sensor assemblies, the size range covers the most common small-spring applications encountered in electronics and mechanical DIY.
Steel coil construction maintains spring rate across repeated compression cycles, making these suitable for applications where reliable return force is critical to function.
| Spring Type | Compression (coil) |
|---|---|
| Material | Steel wire |
| Wire Diameter | 0.3 mm / 0.4 mm / 0.5 mm (see variant options) |
| Outer Diameter (OD) | 2 mm – 10 mm (approx. 0.08 in – 0.39 in) (see variant options) |
| Free Length | 5 mm – 100 mm (approx. 0.20 in – 3.94 in) (see variant options) |
| Quantity per Pack | 10 pcs (lengths ≤50 mm) / 5 pcs (lengths 60–100 mm) |
| Finish | See variant options |
| End Type | See variant options |
| Spring Rate | See variant options |
| Weight (per pack) | See variant options |
Wire diameter directly affects spring stiffness (spring rate). A thicker wire (0.5 mm) produces a stiffer spring with higher load capacity, while a thinner wire (0.3 mm) gives a softer, more compliant spring. For light-touch button returns or pen mechanisms, 0.3 mm is typically sufficient. For small actuators or valve returns under moderate load, 0.4 mm or 0.5 mm is more appropriate. Select the wire diameter first, then match OD and length to your bore and travel requirements.
The outer diameter (OD) listed in the variant options is the overall coil diameter measured from the outside of the wire on one side to the outside of the wire on the opposite side. The inner diameter (ID) is approximately OD minus twice the wire diameter. For example, a 0.5 mm wire / 5 mm OD spring has an ID of approximately 4 mm. Use the OD when sizing for a bore (the spring must fit inside a hole) and the ID when sizing for a post (the spring must slide over a shaft).
These springs are made from steel wire and are intended for dry or low-humidity indoor applications such as electronics, mechanical pens, and precision fixtures. They are not specifically treated for outdoor or high-humidity environments. If your application involves moisture exposure, consider applying a light coat of machine oil or selecting a stainless steel spring for that use case.
These steel compression springs are not rated for continuous outdoor or wet-environment use. Prolonged exposure to moisture may cause surface oxidation over time. For outdoor, marine, or food-contact applications, a stainless steel spring would be a more suitable choice. For occasional light moisture exposure, a protective coating such as light oil can extend service life.
Free length is the uncompressed length of the spring. Your required travel (stroke) must be less than the free length minus the solid height (the height when all coils are touching). As a conservative rule of thumb for small springs, plan for a maximum working compression of 30–50% of the free length to avoid coil bind and maintain consistent spring rate. For example, a 20 mm free-length spring can typically provide 6–10 mm of reliable working travel.
For lengths from 5 mm to 50 mm, each pack contains 10 pieces of the selected wire diameter, OD, and length combination. For longer springs (60 mm, 70 mm, 80 mm, 90 mm, and 100 mm), each pack contains 5 pieces. The quantity is shown in the "Length & Quantity (pcs)" variant selector so you always know exactly what you are ordering before adding to cart.
Yes. The small OD range (2 mm–10 mm) and fine wire diameters (0.3–0.5 mm) make these springs well suited for spring-loaded contacts, battery terminals, button return mechanisms, and sensor housings in electronic assemblies. Ensure the spring OD fits within your housing bore with adequate clearance (typically 0.1–0.3 mm) to prevent binding during compression.
