Helical Coil Calculator
Calculate inductance, dimensions, and resonant frequency for helical coils and springs
Calculate Helical Coil Parameters
Diameter measured from center of coil (Radius: 0.00 mm)
Thickness of the wire used for winding
Total number of wire windings around the helix
Distance between consecutive turns (0 for tightly wound)
For resonant frequency calculation
Example Calculation
Spring Coil Design
Coil diameter: 10 mm
Wire diameter: 0.5 mm
Number of turns: 15
Coil spacing: 0.3 mm
Capacitance: 0.46 pF
Results
Wire length: Lw = 15 × √((π×10)² + 0.3²) ≈ 471.3 mm
Coil height: H = 15 × (0.3 + 0.5) = 12 mm
Inductance: L = (10×15)² / (18×10 + 40×471.3) ≈ 1.342 μH
Wire volume: V = π × 0.5² × 471.3 / 4 ≈ 92.53 mm³
Resonant frequency: f = 1/(2π√(1.342×10⁻⁶ × 0.46×10⁻¹²)) ≈ 202.6 MHz
Coil Applications
Inductors
RF circuits, filters
High Q factor designs
Springs
Mechanical energy storage
Shock absorption
Heat Exchangers
Increased surface area
Thermal applications
Design Tips
Tight Winding
Zero spacing maximizes inductance per unit length
Aspect Ratio
D/H = 1-2 gives good balance of L and Q
Wire Selection
Thicker wire reduces resistance but increases size
Core Material
Ferrite cores can increase inductance 10-100x
Understanding Helical Coils
What is a Helical Coil?
A helical coil is formed when wire or tubing is wound in a helical (corkscrew) pattern around a cylindrical axis. This versatile geometry is used in inductors, springs, antennas, and heat exchangers, with each application optimized for different properties.
Key Parameters
Coil Diameter (Dc) is measured to the center of the wire.Wire Diameter (Dw) affects both mechanical strength and electrical properties. Pitch/Spacing (S) controls the density of windings, while Number of Turns (N) primarily determines inductance.
Applications
- •RF inductors in radio and wireless circuits
- •Mechanical springs for shock absorption
- •Heat exchanger coils for thermal transfer
- •Helical antennas for satellite communication
Key Formulas
Inductance (Wheeler's Formula)
L = (Dc × N)² / (18 × Dc + 40 × Lw)
Result in microhenries (μH)
Wire Length
Lw = N × √((π × Dc)² + S²)
Total length of wire used
Coil Height
H = N × (S + Dw)
Overall coil height
Wire Volume
V = π × Dw² × Lw / 4
Material volume calculation
Note: Wheeler's formula is accurate for air-core coils with diameter-to-length ratios between 0.2 and 5. For ferrite cores, multiply inductance by the relative permeability.