How to Find the Scale Length of a Prefab Guitar Neck

Byadmin October 27, 2025

Table of Contents

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Got a guitar neck, but no idea what the scale length is?
If the neck already has frets, figuring it out is simple – and essential for proper bridge placement, especially in DIY builds.
Recently, I published the Fret Calculator tool to get the fret positions on the neck depending on the planned scale length. But when you have the fretted neck, the task is opposite: to figure out the scale length.
It’s especially important to the CBG builders because the cigar boxes have a pretty small size. And not every box will be long enough to accomodate the desired scale length

🎯 Why You Need to Know the Scale Length

Scale length determines how far apart your frets are and where your bridge should go. If you get it wrong, your guitar won’t intonate properly – and won’t sound right.

📏 How to Measure Scale Length

You only need a ruler or tape measure.

Measure from the nut (where the string first touches the neck)
To the center of the 12th fret
Double that number

👉 That’s your guitar’s scale length.

✅ Example: If the nut-to-12th fret distance is 12.75″,
Then the scale length is 25.5 inches

⚠️ Important Note

This method only works if your neck already has frets installed. If the neck is blank or unmarked, you’ll need to follow a different process: welcome to my Fret Calculator. There, you can get your fret positions depending the scale length you choose.

🎸 What’s Next?

Now that you know the scale length, use it to:

Position your bridge correctly
Match the neck with a fretboard extension
Ensure your intonation is accurate

If you’re working on a blank fretboard or making your own, plug your scale length into the DIY Guitar Fret Calculator to get accurate fret positions.