Radar Range Calculator
Maximum detection range for FMCW and pulse-Doppler radar, from the radar range equation with coherent integration gain. Works for 24 GHz, 60 GHz, 77 GHz and 79 GHz mmWave sensors as well as lower-frequency modules.
Inputs
SNR vs range
Green rows meet your required SNR.
| Range | SNR |
|---|
How the range is calculated
The calculator solves the standard radar range equation for a point target, modified with coherent integration gain:
R_max = [ (P_t · G² · λ² · σ · N) / ((4π)³ · k · T₀ · B · F · SNR · L) ]^(1/4)| Symbol | Meaning | Unit |
|---|---|---|
| P_t | Transmit power | W |
| G | Antenna gain, linear (Tx = Rx) | — |
| λ | Wavelength, c / f | m |
| σ | Target radar cross section | m² |
| N | Coherently integrated pulses | — |
| k | Boltzmann constant, 1.380649 × 10⁻²³ | J/K |
| T₀ | Standard noise temperature, 290 | K |
| B | Receiver noise bandwidth | Hz |
| F | Noise figure, linear | — |
| SNR | Required signal-to-noise ratio at the detector, linear | — |
| L | Total system loss, linear | — |
Receiver sensitivity
The minimum detectable signal is the thermal noise floor scaled by noise figure and the required SNR:
P_min = k · T₀ · B · F · SNR
Range resolution follows from the swept bandwidth, not from the centre frequency:
ΔR = c / (2B). A 100 MHz sweep gives 1.5 m; a 1 GHz sweep gives 15 cm.
Reading the output honestly
Noise bandwidth is the most abused number in radar datasheets. A 24 GHz front end at 10 dBm with 12 dBi antennas has a sensitivity of about −71 dBm across a 100 MHz receiver bandwidth, which puts a 1 m² target at only 5 m. Narrow the post-FFT bandwidth to 1 MHz and the same hardware, at the same power, reaches roughly 45 m in free space.
Neither number is wrong. They describe different processing. That is also why two vendors can quote 8 m and 40 m for electrically similar modules: before you compare, ask what bandwidth, what integration count and what target RCS the figure assumes. A datasheet that does not state all three is not a specification, it is a hope.
Common questions
Which noise bandwidth should I enter?
Use the bandwidth of one range bin after the range FFT — roughly the ADC sampling rate divided by the FFT length, or 1/T for a single chirp. Do not enter the RF sweep bandwidth. A sensor sweeping 1 GHz with a 10 MSPS ADC and a 1024-point FFT has a noise bandwidth near 10 kHz, not 1 GHz, and using the wrong one changes the answer by a factor of five.
What SNR do I need?
13 dB per pulse is a reasonable starting point for a single-pulse detector (Swerling 1 target, 90 % detection probability, 10⁻⁶ false alarm rate). If your processor integrates before thresholding, put the per-pulse requirement here and let N do the rest.
Why does doubling transmit power only add 19 % range?
Because range goes as the fourth root of the energy budget. A 6 dB power increase — four times the power — buys about 41 % more range. This is why antenna gain and integration time matter far more than raw output power in mmWave design.
Does this work for 60 GHz and 79 GHz?
Yes. Enter the centre frequency and the result scales with λ². Higher frequency means a shorter wavelength and more path loss for the same antenna aperture, which is why 79 GHz automotive radar compensates with much higher antenna gain and wider bandwidth. Note that allowed bands and power limits differ by country — check local regulation before you specify a frequency.
What about laser radar (LiDAR)?
No. LiDAR range follows the optical radar equation with a 1/R⁴ or 1/R² dependence depending on target type, and atmospheric extinction dominates. A separate calculator is on the roadmap.
Sourcing mmWave radar modules or finished sensors?
I work directly with Chinese radar manufacturers — modules and turnkey units for perimeter security, presence detection, traffic and parking. Tell me the application and the range you need, and I will tell you which architecture actually fits instead of quoting the first datasheet.