Calculate quarter-wave (λ/4) and half-wave (λ/2) transmission line lengths for any frequency and substrate. Includes FR4, Rogers RO4003C, RT/Duroid 5880, and free space values.
Interactive λ/4 Calculator
Quarter-Wave Length for Any Frequency and Substrate
Free-space wavelength λ₀
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Guided wavelength λg
—
Quarter-wave λg/4
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Half-wave λg/2
—
3λg/4 length
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Phase velocity
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Quarter-Wave Length Reference Table
Frequency
Free space λ/4
FR4 λ/4
RO4003C λ/4
Duroid 5880 λ/4
433 MHz
173.1 mm
93.5 mm
103 mm
126 mm
900 MHz
83.3 mm
45.0 mm
49.7 mm
60.6 mm
1.8 GHz
41.6 mm
22.5 mm
24.8 mm
30.3 mm
2.4 GHz
31.2 mm
16.9 mm
18.6 mm
22.7 mm
5 GHz
15.0 mm
8.1 mm
9.0 mm
10.9 mm
28 GHz
2.68 mm
1.44 mm
1.60 mm
1.95 mm
RF View Wavelength Calculator: RF View's Microstrip Calculator includes guided wavelength and λ/4 length in its output. Enter frequency, substrate εr, and height H for precise calculation. Free offline on Android.