FIR Filter Frequency Response Calculator
Evaluate the magnitude and wrapped phase of an entered real FIR filter at a query frequency and plot its DC-to-Nyquist response.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Sum the delayed complex tap contributions at the query and on a DC-to-Nyquist plotting grid.
H(f)=Σh[n] exp(−i2πfn/fs); gain dB=20log10|H|
Worked example
Taps [0.25,0.5,0.25] at sample rate 1000 Hz give magnitude 0.5 and phase −90° at 250 Hz. DC gain is 1 and Nyquist gain is zero.
Assumptions and input details
1–128 finite real causal taps and query between 0 and fs/2. Values at numerical nulls within 1e−12 of the tap absolute-sum scale show zero magnitude and undefined phase/dB. Phase is wrapped, not unwrapped; group delay is not supplied. This analyzes entered taps without designing or validating a filter, inferring stopband guarantees or processing uploaded audio.
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
SI prefixes are explicit: for example, milli means one thousandth, micro one millionth and kilo one thousand. Changing a unit changes the interpretation of the entered number.
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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