Tools

Cellular signal quality interpreter

Paste the radio values your modem reports — CSQ, RSSI, RSRP, RSRQ, SINR — and get a plain verdict per metric plus the exact CSQ↔dBm conversion. The CSQ↔dBm math follows 3GPP TS 27.007 §8.5; the quality thresholds are based on the 3GPP TS 36.133 measurement ranges. Everything is computed in your browser.

Fill in at least one metric. Leave blank whatever your modem doesn't report.

Enter a CSQ, RSSI, RSRP, RSRQ or SINR value to see the verdict.

What each metric measures

CSQ is the most common reading on 2G/3G and the one AT+CSQ returns: an index from 0 to 31 that maps to received power via RSSI = -113 + 2·CSQ dBm, plus the value 99 meaning "not measurable". RSSI is that same wideband received power, noise included. On LTE and NB-IoT/LTE-M the metrics that matter are different: RSRP measures the per-resource reference-signal power (the real coverage), RSRQ measures relative quality (wanted power against interference and cell load), and SINR summarizes the signal-to-noise ratio that sets the achievable throughput. A device can show a high RSRP and still connect poorly if RSRQ or SINR are low from congestion or interference — which is why it pays to read all three, not just the coverage bar.

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Frequently asked questions

How do you convert CSQ to dBm?
With the 3GPP TS 27.007 formula: RSSI in dBm = -113 + 2 × CSQ, valid for the CSQ range 0 to 31. So CSQ 0 is -113 dBm or less, CSQ 31 is -51 dBm or more, and each CSQ point equals 2 dB. The value 99 is a separate case: it means the modem cannot detect or measure the signal, not that the signal is very low.
What RSRP value is good for an IoT device?
As a guide: above -80 dBm is excellent, -80 to -90 dBm is good, -90 to -100 dBm is fair, -100 to -110 dBm is weak, and below -110 dBm the connection is usually unstable. NB-IoT devices tolerate lower RSRP thanks to repetition gain, but below -115 dBm it's worth improving the antenna or the site.
How do RSRP, RSRQ and SINR differ?
RSRP is the absolute reference-signal power (how much signal arrives). RSRQ is a quality ratio combining power and cell load (how clean that signal is). SINR compares the wanted signal against noise plus interference and is the best predictor of throughput. Good RSRP coverage with poor RSRQ or SINR points to interference or congestion, not to a lack of signal.
Does it work for NB-IoT and LTE-M?
Yes. RSRP, RSRQ and SINR are the reference metrics on LTE and its IoT variants NB-IoT and LTE-M; the ranges we apply come from 3GPP TS 36.133. CSQ is still available via AT+CSQ on most modules as a quick read, although on LTE looking at RSRP is more informative.

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