Signal-to-Noise Ratio Calculator

Created by Komal Rafay
Reviewed by Dominik Czernia, PhD candidate and Jack Bowater
Last updated: Aug 01, 2022

Our signal-to-noise ratio calculator is a tool that will help you find the ratio of the desired signal to the background noise. You might wonder: "Why is calculating this ratio so important?" You will get your answer in a while, but before that, you need to know what SNR is and what a good signal-to-noise ratio is.

Continue reading to learn some significant signal-to-noise ratio requirements and the difference between low and high signal-to-noise ratios.

What is SNR?

SNR stands for signal-to-noise ratio. This ratio is a measure of the strength of the desired signal to the current level of background noise. Below are some signal-to-noise ratio examples we use in the real world:

  • Finding isotope levels in ice cores;
  • Measuring the efficiency of a cell's biochemical signaling;
  • Determining a car amplifier's sound clarity; and
  • Computing a communication channel's bandwidth and capacity 📡.

Signal-to-noise ratio calculator

Our signal-to-noise ratio calculator is a convenient tool that calculates the ratio between the desired signal level and the acceptable background noise.

Now, let's come back to our original question, "Why is calculating this ratio so important?"

Imagine you are having a conversation with your friend, and it's going swimmingly. Now, imagine you a lot more people arrive and everyone is talking to someone while you are trying to have a conversation with your friend. It's still lovely but your friend gets cut off more and more. Now, imagine you are at a concert, and you want to chat with your friend. It seems tedious and exhausting trying to repeat what you're saying because of the loud music, which for you is the background noise.

Your voice here is the signal, and the concert music is the noise.

Our calculator lets you calculate the signal-to-noise ratio using five various methods.
In the tool, you have the option to select the type of SNR; whichever type you choose, you need to input:

  • The magnitude of the signal; and
  • The magnitude of the noise.

Each type has various unit associated with it. Also, some of them may appear unitless, but it is good to remember that they can be of any appropriate unit as long as both signal and noise are in the same units.

Signal-to-noise ratio calculation is an essential concept in science and engineering, and we can use it to measure any form of signal or transmission. So, after learning what the signal-to-noise ratio is, let's find out what a good SNR is.

What is a good signal-to-noise ratio?

The signal-to-noise ratio is expressed as a single numerical value, in decibels (dB).
The ratio can either be zero, positive or negative. An SNR ratio greater than zero indicates that the signal strength is higher than the noise level. When the value from the SNR formula is zero, then the signal has the same strength as the noise. Finally, a negative SNR means that the signal is weaker than the noise.

So, what is the signal-to-noise ratio value that we should aim for?

  • High signal-to-noise ratio 👍
    A high signal-to-noise ratio means anything greater than zero. But the greater the SNR value, the greater the signal is in comparison to the noise. This means that, no matter which type of transmission has to take place, it will be efficient and accurate.

  • Low signal-to-noise ratio 👎
    If the SNR value is low, it means that the noise is greater than the acceptable value and this will disrupt any form of data transfer. For example, this can occur during the transfer of text, image, audio & video streams, and telemetry.

How to calculate signal-to-noise ratio? SNR formula

The signal-to-noise ratio calculator has five different SNR formulae within it. This allows you to calculate various types of SNR based on what your input signal is or which unit you measure the data in:

  1. Signals ratio;
  2. SNR from decibels;
  3. Power SNR;
  4. Voltage SNR; and
  5. SNR from the coefficient of variation.

All five types of SNR require you to input:

  • The strength of the signal; and
  • The level of noise.

As a result, you will obtain the signal-to-noise ratio based on the type you have selected.

For instance, if your signal is 6 volts and the noise is 4 volts, you need to select Voltage SNR. Then, the result is 3.522 dB.

The variation in the type of signal-to-noise ratio lies in the formula. As we mentioned above, there are five ways to calculate the SNR:

  1. SNR as signal ratio in absolute units:

    SNR=signal/noiseSNR = \text{signal} / \text{noise}

  2. SNR as signal difference in decibels:

    SNR(dB)=signal (dB)noise (dB)SNR \text{(dB)} = \text{signal (dB)} - \text{noise (dB)}

  3. Power SNR:

    pSNR=10×log(signal / noise)pSNR = 10 \times \log{(\text{signal / noise})}

  4. Voltage SNR:

    vSNR=20×log(signal / noise)vSNR = 20 \times \log{(\text{signal / noise})}

  5. SNR from the coefficient of variation.

    a. SNR=μ/σSNR = \mu / \sigma

    b. SNR=μ2/σ2SNR = \mu ^2 / \sigma ^2

where:

  • SNR(dB)SNR(dB) - The signal-to-noise ratio in decibels;

  • pSNRpSNR - The power signal-to-noise ratio;

  • vSNRvSNR - The voltage signal-to-noise ratio;

  • μ\mu - The signal mean; and

  • σ\sigma - The standard deviation of the noise.

💡 Remember, the logarithmic base is always in 10 in the above equations.

Signal-to-noise ratio requirements and signal-to-noise ratio example

📶 Generally, the recommended SNR for wireless networks to use the internet is 20 dB. The table below shows some SNR values and what their requirements for connectivity are:

SNR values

Requirements

5 - 10 dB

Cannot establish a connection

10 - 15 dB

Can establish an unreliable connection

15 - 25 dB

Acceptable level to establish a poor connection

25 - 40 dB

Considered a good connection

41+ dB

Considered to be an excellent connection

These signal-to-noise ratio statistics play a significant role in the field of wireless communication. Another good thing to remember is that the increase in SNR may increase the wireless network's channel capacity. Check out our baud rate calculator and modulation calculator to understand how data is transmitted using signals.

FAQ

How do I calculate the signal-to-noise ratio?

To calculate the signal-to-noise ratio, you need the level of both the signal and the noise. Then:

  1. If you have the signals in decibels (dB), subtract noise from the signal.
  2. If your calculations are in watts, use the power signal-to-noise ratio formula SNR = 10 × log(signal / noise).
  3. If your calculations are in volts, use the voltage signal-to-noise ratio formula SNR = 20 × log(signal / noise).
  4. log denotes the common logarithm.

What is a good signal-to-noise ratio?

For instance, in terms of data network, a good SNR (signal-to-noise ratio) is 20 dB or above. And if the network is meant to use voice applications, then it needs to be 25 dB or above.

A good signal-to-noise ratio is one that has signal levels much higher than noise levels, as the greater the noise levels, the more disruption is caused. A low signal-to-noise ratio means that the level of background noise is more than it should be in comparison to the required signal.

What is the signal-to-noise ratio of a 450dB signal and a 350 dB noise?

The signal-to-noise ratio (SNR) for a signal of 450dB and noise of 350 dB is 100dB.

The signal and noise level values are already in decibels (dB), so the signal-to-noise ratio formula is:

SNR(dB) = signal - noise

What kind of noises can impact the signal-to-noise ratio?

Noise that impacts signal-to-noise ratio can be electronic, thermal, quantum, biological, or acoustic. Also, we can consider humidity as noise. Generally, you may treat any unwanted disturbance that impacts the quality of the signal as noise.

A significant amount of noise can cause disruption in text, graphics, audio, and video transfers.

Komal Rafay
Type of SNR
Power SNR
Signal
hp(E)
Noise
hp(E)
Signal-to-noise ratio
dB(s)
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