Wireless Interference Calculator
Turn signal, co-channel, adjacent-channel and noise-floor levels into SNR, SINR and the modulation the link can actually hold.
About Wireless Interference Calculator
Decibel values cannot be added, so each level is converted to linear power, the interference and noise terms are summed, and the ratio is converted back to dB. Adjacent-channel energy is attenuated by the receiver filter, which is why co-channel interference hurts far more. Survey tools report signal strength, but clients choose their modulation from SINR, which is why a strong -62 dBm signal can still deliver BPSK throughput on a contended channel.
Formula
Wireless Interference
SINR = 10·log10(S ÷ (I_co + I_adj + N)) with every level converted from dBm to milliwatts first; adjacent-channel power is reduced by the receiver's rejection figure.
- S
- Wanted signal power in mW
- I_adj
- Adjacent-channel power after rejection
- N
- Thermal and ambient noise power
Worked example
With the default values below, Wireless Interference Calculator returns SINR of 13.82. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Wanted signal levelaccepts -100–-20 dBm
- -62 dBm
- Strongest co-channel interfereraccepts -110–-20 dBm
- -78 dBm
- Strongest adjacent-channel interfereraccepts -110–-20 dBm
- -70 dBm
- Adjacent-channel rejectionaccepts 0–50 dB
- 10 dB
- Noise flooraccepts -110–-60 dBm
- -95 dBm
Results
- SINR
- 13.82 dB
- SNR (Interference Ignored)
- 33.0 dB
- Loss Caused by Interference
- 19.18 dB
- Highest Sustainable Modulation
- MCS 1 — QPSK 1/2
Step by step
- 1Values used
- 2Wireless Interference
- 3SINR= 13.82 dB
- 4SNR (Interference Ignored)= 33.0 dB
- 5Loss Caused by Interference= 19.18 dB
- 6Highest Sustainable Modulation= MCS 1 — QPSK 1/2
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Wireless Interference calculated?
SINR = 10·log10(S ÷ (I_co + I_adj + N)) with every level converted from dBm to milliwatts first; adjacent-channel power is reduced by the receiver's rejection figure. Decibel values cannot be added, so each level is converted to linear power, the interference and noise terms are summed, and the ratio is converted back to dB. Adjacent-channel energy is attenuated by the receiver filter, which is why co-channel interference hurts far more.
Why does Wireless Interference matter?
Survey tools report signal strength, but clients choose their modulation from SINR, which is why a strong -62 dBm signal can still deliver BPSK throughput on a contended channel.
What values do I need to enter?
This calculator takes 5 inputs: Wanted signal level, Strongest co-channel interferer, Strongest adjacent-channel interferer, Adjacent-channel rejection, Noise floor. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.