Wavelength Calculator
Wavelength is the spatial period of a wave — the distance between two successive peaks. In a dielectric medium the wavelength shortens by √εᵣ compared to free space. This affects antenna sizing, transmission line lengths, and when something is "electrically small".
Equations & Parameters ▸
\(\lambda = \dfrac{c}{f\sqrt{\varepsilon_r}}\)
| f | Operating frequency. |
| εᵣ | Relative dielectric constant of the medium. Free space = 1, FR4 ≈ 4.4, PTFE ≈ 2.1. |
| λ | Wavelength = c/(f√εᵣ). |
| λ/2 | Dipole resonant length. |
| λ/4 | Quarter-wave transformer / monopole length. |
Physical constants used
| c | Speed of light = 2.998×10⁸ m/s |
| µ₀ | Permeability of free space = 4π×10⁻⁷ H/m ≈ 1.2566×10⁻⁶ H/m |
| ε₀ | Permittivity of free space = 8.854×10⁻¹² F/m |
Inputs
Carrier or signal frequency
1 for air, ≈4.4 for FR4, ≈2.1 for PTFE
Results
Wavelengths
λ (full wave)—
λ/2 (dipole)—
λ/4 (quarter-wave)—
Diagram