Banjo action height
Deering, the banjo maker, measures action at the 22nd fret, where the neck meets the rim: 1/8″ (3.17 mm) from the top of the fret to the underside of the strings, the same on the bass and treble sides, with 0.015–0.020″ (0.38–0.51 mm) of neck relief.
Banjo action, Deering
String height at the 22nd fret and neck relief, from Deering's neck adjustment guide.
| Instrument | Low (mm) | High (mm) | Relief (mm) | Fret |
|---|---|---|---|---|
| Banjo | 3.2 | 3.2 | 0.4–0.5 | 22 |
How to use it
- Tune to pitch (open G: g D G B D) with the bridge in the spot where intonation is right.
- Measure at the 22nd fret, from the top of the fret to the underside of the 4th and 1st strings, and enter both. The 26.25″ scale is already filled in.
- Read how much the bridge has to change, swap to a bridge of that height or adjust the neck angle, then retune and measure.
Help and explanations
A banjo has no saddle to sand. Action depends on the height of the bridge, the angle of the neck against the rim and the relief. The calculator converts your reading into how much lower or taller the bridge needs to be.
The 22nd fret and the bridge
On a 26.25″ (666.75 mm) scale the 22nd fret is 480 mm from the nut, so the bridge has to move 1.39 times the change you want there. A banjo measuring 4.0 mm at the 22nd needs a bridge about 1.15 mm (0.045″) lower to reach Deering's 1/8″.
Bridges are sold in several heights, so the usual fix is the next size down rather than sanding the feet. If you do sand, keep both feet flat on the head. Check head tension first: a loose head lets the bridge sink and the action drift as you play.
Relief and neck angle
Deering's 0.015–0.020″ of relief is more than most electric guitar specs. Deering checks it with a capo at the 1st fret and the string held at the 22nd, reading the gap at the 7th fret; two business cards stacked are about right. On a Deering the truss rod nut sits under a small cover at the front of the peghead: clockwise reduces relief, counterclockwise adds it, 1/8 to 1/4 turn at a time.
On banjos with coordinator rods inside the pot, the rods also adjust the action and anchor the neck to the rim. Deering urges caution: hold the rod still, turn the nuts a quarter turn at a time and leave bigger changes to a repairer, because overturning them can crack the rim or pull out the hanger bolt.
Tips
- A banjo bridge is held in place only by string pressure: after swapping it, slide it until the 12th-fret notes match, using the intonation checker.
- Lighter or heavier strings change the pull on the head and neck: compare sets in the string tension calculator.
- Tuning the 5th string to g4 is quick with the banjo tuner.
Frequently asked questions
What is the standard action on a banjo?
Deering sets 1/8″ (3.17 mm) at the 22nd fret, measured from the top of the fret to the underside of the strings.
Where do you measure banjo action?
Deering measures at the 22nd fret, where the neck meets the rim. If you measure at the 12th, the reading is lower; use the 22nd to compare with Deering's figure.
How much relief should a banjo neck have?
Deering gives 0.015–0.020″ (0.38–0.51 mm), read at the 7th fret with a capo at the 1st and the string held at the 22nd.
How do I lower the action on a banjo?
Check relief, then use a lower bridge or adjust the neck angle. At the 22nd fret the bridge must change 1.39 times the action change: 1.15 mm lower to go from 4.0 mm to 1/8″.
Does bridge height affect banjo tone?
Yes. A taller bridge increases the string angle and pressure on the head; a lower one softens it. That's why changing the neck angle is sometimes preferred to a much lower bridge.