ONE FORMULA, ONE ANSWER
Sampling Alias Frequency Calculator
Fold a uniformly sampled real sinusoid into the frequency interval from zero to half the sampling rate. Choose input units and calculate one value within the stated conditions.
Inputs
Calculations run in this browser. Scientific notation such as 1.2e-3 is supported. Do not group thousands.
Result
Frequency in the first Nyquist zone f_alias
Enter values and select Calculate.
r = f mod f_s; f_alias = min(r, f_s−r)
Assumptions
Required: ideal uniform sampling of a single real sinusoid. The result is its unsigned folded frequency; phase, amplitude and recoverability are outside this model. At DC or the Nyquist boundary, observed amplitude also depends on phase. This tool limits f/f_s to 2³² to protect numerical precision. The actual analog input bandwidth and filters require separate checks.
Displayed values are floating-point approximations. Design safety factors and unprovided error contributions are not calculated.
Formula references and credits
NaNa Lab created the code, descriptions, icons and preview images. Text, figures and code from the linked references have not been reproduced.
Physical constants: NIST / CODATA 2022. The values of μ₀ and ε₀ are measured recommendations, not exact defining constants. Values and precision notes are in the source record.
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