Guitar Intonation Always Sharp or Flat [Solved]

The beauty of a well-played guitar lies not only in the skill of the guitarist but also in the precise tuning & intonation of the instrument. However, many players encounter the frustrating issue of their guitar’s intonation consistently being sharp or flat. In this guide, we will explore the reasons behind this problem, delve into the intricacies of guitar intonation, and provide effective solutions to help you achieve perfect pitch.

Guitar Intonation Always Sharp or Flat

Why Does Guitar Intonation Go Sharp or Flat?

1. Temperature & Humidity Changes:

Guitars are sensitive to environmental factors such as temperature & humidity. As these variables fluctuate, they can cause the wood to expand or contract. Which is affecting the tension on the strings and, consequently, the intonation.

Solution: Store your guitar in a controlled environment, using a humidifier during dry seasons & dehumidifier when it’s too humid. This helps maintain a stable environment for your instrument.

2. String Quality and Age:

Strings, especially older ones, can lose their elasticity and develop uneven tension. This results in poor intonation, making the guitar sound sharp or flat across different frets.

Solution: Regularly change your guitar strings, and ensure that you use high-quality strings suitable for your playing style and genre.

3. Incorrect Bridge Placement:

In some cases, the bridge may not be properly aligned, that is causing the scale length to be inaccurate. This misalignment can lead to sharp or flat intonation.

Solution: Consult a professional luthier to ensure that your guitar’s bridge is correctly placed. Adjustments may be necessary to achieve the optimal scale length.

4. Neck Relief Issues:

A guitar’s neck should have a slight curve, known as relief. Too much or too little relief can impact intonation. Changes in humidity and temperature can affect the neck’s curvature, leading to intonation problems.

Solution: Regularly check and adjust the neck relief using the truss rod. Seek professional assistance if you are unfamiliar with truss rod adjustments.

How to Check Your Guitar’s Intonation –

Before delving into solutions, it’s crucial to accurately diagnose whether your guitar’s intonation is indeed sharp or flat. Follow these steps to check your guitar’s intonation:

1. Tune Your Guitar:

Ensure your guitar is perfectly tuned using an electronic tuner or a tuning app.

2. Play the 12th Fret Harmonic:

Gently touch the string above the 12th fret without pressing it down. Pluck the string, producing a harmonic tone.

3. Compare with the 12th Fret Note:

Now, press down the string on the 12th fret and play the note. Compare it with the harmonic tone. If the fretted note is sharp or flat compared to the harmonic, your guitar’s intonation needs adjustment.

4. Repeat for Other Frets:

Perform the same process on other frets to identify specific areas where the intonation is off.

When to Adjust Guitar Intonation?

Regularly checking and adjusting your guitar’s intonation is essential for maintaining optimal playability. However, there are specific instances when adjustments are particularly crucial:

1. Changing String Gauge:

Switching to a different string gauge can impact the tension on the neck and, consequently, the intonation. Always check and adjust intonation after changing string gauges.

2. Seasonal Changes:

As mentioned earlier, temperature and humidity variations can affect your guitar. Check the intonation whenever you notice significant environmental changes.

3. After Neck Adjustments:

If you’ve recently adjusted the neck relief, it’s vital to check and readjust the intonation as well.

How to Fix Sharp or Flat Intonation?

Now that we’ve identified potential causes let’s explore effective solutions to fix sharp or flat intonation:

1. Adjusting Saddle Position:

The saddle is a critical component affecting intonation. Use a screwdriver to adjust the saddle position. If the 12th fret note is sharp, move the saddle backward; if it’s flat, move it forward.

2. Checking Nut Slot Heights:

Inaccurate nut slot heights can also contribute to intonation issues. Ensure that the slots are appropriately sized and filed for each string.

3. Examining Fret Wear:

Worn-out frets can cause intonation problems. If you observe significant fret wear, consider a fret dressing or a complete fret job.

4. Professional Setup:

For complex intonation issues or if you’re unsure about DIY adjustments, seeking the expertise of a professional guitar technician or luthier is advisable. They can perform a comprehensive setup, addressing various factors affecting intonation.


Achieving perfect guitar intonation is a journey that requires diligence, attention to detail, and a fundamental understanding of the instrument’s mechanics. By identifying the reasons behind sharp or flat intonation and applying the appropriate solutions, you can enhance the overall playability and tonal quality of your guitar.

Regular maintenance, coupled with professional assistance when needed, ensures that your guitar remains in optimal condition for years to come. Keep your instrument finely tuned, and let your music resonate with precision and clarity.

Last Updated on December 5, 2023 by Perry Garner

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