This tool allows you to calculate the Root mean square value of Error Vector Magnitude (EVM) to its deciBel (dB) equivalent. It also computes the dB value from RMS.

**Formula**

**EVM _{RMS} = 100 * 10^(EVM_{dB}/20)**

**EVM _{dB} = 20 * LOG_{10}^(EVM_{RMS}/100)**

**How to use the calculator**

EVM is a measure of modulation quality of a communication system. Enter a number in **either** field of the tool. The dB value should be a negative number lower than zero. The percent value should be a number between 0 and 100.

ðŸ”Ž The lower the value of EVM either in percentage or dB, the lower the error. This translates directly to lower Bit error rate and higher quality signals.

**Example calculations**

A value of -40 dB translates to 1% EVM.

**What is a good value of EVM?**

The answer depends on the modulation format and target performance levels. For 802.11 Wi-Fi systems, the IEEE for instance requires -30 dB EVM for 256 QAM modulation and coding rate of 3/4. As the modulation constellation size increases from 256 to higher, the target EVM becomes lower.

**Related calculators**

- EVM dB to Percentage Calculator