A fretboard radius gauge helps you check the curve of a guitar’s fingerboard and match the strings or bridge saddles to it. The right style depends on whether you’re measuring a bare board, checking a strung guitar, or doing a broader setup.
These 10 picks range from focused gauge sets to multi-tool kits. Use the guide below to choose the shapes, radius markings, and extras you’ll actually use.
Best 10 Guitar Fretboard Radius Gauges Picks for 2026
Best for Visibility
MusicNomad MN603 Two-Piece Radius Gauge Set
- Eight radius measurements
- Black finish highlights string contact
- Stainless steel with etched markings
Best For: Clear visual checks of fretboard and string radius
Best for Standard Setups
StewMac Four-Piece Understring Gauges
- Four common radius sizes
- Slim understring design
- Fits spreads up to 2-5/8 inches
Best For: Standard-width guitar and four-string bass setups
Best Simple Two-Piece Set
Alnicov Stainless Steel Radius Gauges
- Eight radii on two gauges
- Checks fingerboard or bridge curvature
- Stainless steel construction
Best For: Compact fretboard and bridge curvature checks
Best with Action Ruler
10-Piece Luthier Radius Gauge Kit
- Nine understring radius sizes
- Includes metric/imperial action ruler
- Stainless steel tools
Best For: Combined radius and string-action measurements
Best Notched Set
KAISH Stainless Steel Radius Gauges
- Four notched stainless steel gauges
- Eight radii from 7.25 to 20 inches
- Narrow and wide profiles for different neck positions
Best For: Checking radius with strings installed
Best Setup Kit
Mudder 15-Piece Guitar Gauge Kit
- Nine understring radius sizes
- Eight radii on the notched gauges
- Includes action ruler and foldable feeler gauge
Best For: Radius checks plus broader setup measurements
Best Understring Set
- Nine sizes from 7.25 to 20 inches
- Made for bridge-saddle radius setup
- Includes action ruler and pin puller
Best For: Matching bridge saddles to fingerboard radius
Most Complete Setup Kit
TIMESETL 17-Piece Luthier Tool Set
- Four notched and nine understring gauges
- 32-blade feeler gauge and action ruler
- Includes two fingerboard guards
Best For: Combined radius, clearance, and action measurements
Radius-Only Pick
Dreamtop 9-Piece Understring Gauge Set
- Nine radii from 7.25 to 20 inches
- Checks from above or below strings
- No action ruler or feeler gauge
Best For: Adding understring gauges to an existing tool kit
Balanced Radius Kit
TIMESETL 14-Piece Gauge and Action Set
- Four notched and nine understring gauges
- Includes a string-action ruler
- No feeler gauge listed
Best For: Radius and action checks in one kit
Best for Visibility – MusicNomad MN603 Two-Piece Radius Gauge Set
These guitar fretboard radius gauges pair eight common measurements with a black finish that makes it easier to see when strings touch the gauge. The two-piece stainless steel set measures both fretboard and string radius on electric, acoustic, and bass guitars.
Best For: Players who want clear visual feedback when checking string radius.
Pros:
- Covers 7.25, 9.5, 10, 12, 14, 15, 16, and 20 inches.
- Black finish helps reveal string contact.
- Polished edges and laser-etched measurements support repeated use.
Cons:
- Does not include a string-action ruler.
- No 17-inch radius measurement is listed.
The etched instructions are a useful touch if you want a compact set without relying on a separate reference sheet.
Best for Standard Setups – StewMac Four-Piece Understring Gauges
If your guitar fretboard radius gauges need to fit beneath installed strings, this four-piece StewMac set is made for that job. Its slim profile fits tight clearances, while the lower edge checks fretboard radius and the upper arc guides saddle-height adjustments.
Best For: Common six-string guitar and four-string bass setups that need understring access.
Pros:
- Includes 7.25-, 9.5-, 12-, and 16-inch gauges.
- Works with string spreads up to 2-5/8 inches.
- Backed by StewMac’s Lifetime Promise and expert support.
Cons:
- Four included radii offer fewer choices than broader sets.
- Standard width may not suit string spreads beyond 2-5/8 inches.
This is a focused choice when understring clearance and the four supplied radii match your instruments.
Best Simple Two-Piece Set – Alnicov Stainless Steel Radius Gauges
Alnicov 2PCS Guitar Fingerboard Fretboard Saddle Nut Radius Gauges Measuring Tool
Check Price On AmazonThese guitar fretboard radius gauges put eight measurements across just two stainless steel pieces. They are intended for finding the curvature of a fingerboard or bridge without carrying a larger collection of individual gauges.
Best For: Players who want a compact set covering common fretboard and bridge radii.
Pros:
- Covers 7.25, 9.5, 10, 12, 14, 15, 16, and 20 inches.
- Two-piece format is convenient to carry.
- Stainless steel construction supports durability.
Cons:
- No 17-inch radius measurement is listed.
- No string-action ruler is included.
Choose this set if the listed radii match your instruments and you mainly need straightforward curvature checks.
Best with Action Ruler – 10-Piece Luthier Radius Gauge Kit
This kit expands beyond guitar fretboard radius gauges with nine understring gauges and a double-sided string-action ruler. It covers nine radii, including 17 inches, while the ruler adds metric and imperial markings for setup measurements.
Best For: Players who want radius checks and string-height measurements in one kit.
Pros:
- Includes 7.25, 9.5, 10, 12, 14, 15, 16, 17, and 20-inch gauges.
- Ruler measures string height, bridge height, nut and bridge slot depth, and pickup height.
- Stainless steel tools have etched ruler markings.
Cons:
- Ten separate pieces require more tracking than a two-piece gauge set.
- Product notes advise care around the edges and recommend gloves.
The added ruler makes this the most versatile option here for the stated measurements, but handle the tools with the caution noted by the seller.
Best Notched Set – KAISH Stainless Steel Radius Gauges
For checking fingerboard curvature without removing the strings, these guitar fretboard radius gauges keep the job focused. The four stainless steel gauges provide narrow profiles for use near the nut and wider profiles for use near the body.
Best For: Players and repairers who want a dedicated notched gauge set for checking fingerboard or bridge radius.
Pros:
- Covers eight common radii from 7.25 to 20 inches.
- Notches allow measurements with the strings on.
- Stainless steel construction suits regular shop use.
Cons:
- No string-action ruler or feeler gauge is listed.
Choose this set when radius measurement is the priority; its narrow and wide gauges give you options at different points along the neck.
Best Setup Kit – Mudder 15-Piece Guitar Gauge Kit
If you need guitar fretboard radius gauges alongside other setup measurements, this Mudder kit combines notched and understring gauges with a string-action ruler and foldable feeler gauge. Its stainless steel gauges cover common fingerboard and saddle radii.
Best For: Guitar owners assembling a multi-tool kit for radius, action, and spacing checks.
Pros:
- Nine understring radius sizes, including 17 inches.
- Notched gauges cover eight radii and work without removing the strings.
- Dual-scale action ruler and feeler gauge expand the kit’s measuring uses.
Cons:
- The notched gauges do not list a 17-inch radius, even though the understring gauges do.
This is the more versatile choice if you also plan to measure string height or small gaps, rather than buying radius gauges alone.
Best Understring Set – Alnicov 9-Piece Radius Gauges
These guitar fretboard radius gauges are designed to help match bridge saddles to fingerboard curvature. Alnicov lists nine stainless steel understring gauges, a string-action ruler, and a pin puller in this portable set.
Best For: Players setting saddle radius who also want an action ruler and pin puller.
Pros:
- Nine radius sizes span 7.25 to 20 inches, including 17 inches.
- Understring design supports bridge-saddle radius adjustments.
- Action ruler measures string height and other setup dimensions.
Cons:
- No notched fingerboard gauges are listed.
Pick this set primarily for understring saddle work; if you specifically need notched gauges to check the fingerboard with strings in place, consider a different set.
Most Complete Setup Kit – TIMESETL 17-Piece Luthier Tool Set
If you want guitar fretboard radius gauges alongside other setup measurements, this TIMESETL kit combines four notched gauges, nine understring gauges, a 32-blade feeler gauge, a string-action ruler, and two fingerboard guards.
Best For: Players who want radius, clearance, and action tools in one kit.
Pros:
- Notched gauges help check fingerboard curvature without removing the strings.
- Nine understring gauges cover radii from 7.25 to 20 inches, including 17 inches.
- Feeler blades span 0.0015 to 0.035 inch; the ruler also measures nut height and fret-slot depth.
Cons:
- More tools to store and sort than a radius-gauge-only set.
- Its listed notched-gauge radii do not include 17 inches.
Choose this set when radius checking is only one part of the setup work you plan to do.
Radius-Only Pick – Dreamtop 9-Piece Understring Gauge Set
For shoppers who need guitar fretboard radius gauges rather than a broader tool kit, this Dreamtop set supplies nine stainless steel understring gauges covering 7.25, 9.5, 10, 12, 14, 15, 16, 17, and 20 inches.
Best For: Guitar or bass owners who already have other setup tools and need understring radius gauges.
Pros:
- Measures radius from above or below the strings for fretboard and saddle checks.
- Includes a 17-inch gauge alongside eight other listed radii.
- Stainless steel construction in a compact, gauge-only set.
Cons:
- No notched radius gauges are listed.
- No feeler gauge or string-action ruler is included.
This is the focused choice for checking radius and adjusting bridge saddles, but other setup measurements require separate tools.
Balanced Radius Kit – TIMESETL 14-Piece Gauge and Action Set
This TIMESETL option pairs guitar fretboard radius gauges with a string-action ruler: four notched gauges and nine understring gauges provide two approaches to checking curvature, while the ruler handles action and other height measurements.
Best For: Players who want both styles of radius gauge plus an action ruler, without a feeler gauge.
Pros:
- Notched gauges can check fingerboard curvature without removing the strings.
- Understring gauges cover nine radii from 7.25 to 20 inches, including 17 inches.
- Stainless steel gauges have rounded edges; the ruler includes decimal and metric conversion markings.
Cons:
- No feeler gauge is listed for measuring small clearances.
- The listed notched-gauge radii omit 17 inches, although the understring set includes it.
It fills the gap between a radius-only set and a broader setup kit if action measurements are on your checklist.
How We Picked These Guitar Fretboard Radius Gauges
We considered the gauge styles and tool combinations represented in the selected products: understring gauges, notched gauges, compact two-piece sets, and larger setup kits. The most useful choice is the one that fits the measurement you need to make. A larger piece count is not automatically better if it adds tools you already own or leaves out a radius you need.
Before buying, confirm the listed radius sizes and included pieces on the current product page. Names such as “setup kit” do not tell you whether a set has the specific understring or notched gauge you want.
Quick Comparison: Which Gauge Style Fits the Job?
Understring gauges slip beneath the strings so you can compare their arc at the bridge without removing them. Sets from StewMac, Dreamtop, and Alnicov offer this style; several larger kits include it too. Notched gauges are shaped to clear frets and contact the fingerboard, making them useful when you need to check the board rather than the fret tops. The KAISH set and some TIMESETL kits emphasize notched gauges. Compact sets, such as the MusicNomad and two-piece Alnicov options, suit buyers who want fewer tools to store. Multi-tool kits from Mudder, TIMESETL, and others add setup aids such as action rulers or feeler gauges.
Key Buying Factors
Match the Gauge to the Surface
To check a fretted fingerboard, choose a notched gauge that clears the frets and reaches the wood. For a string-radius adjustment, an understring gauge is the more convenient tool. A standard gauge can help with an unfretted board or other accessible curved surfaces, but check the product’s intended use before relying on it for every task.
Check the Radius Sizes and Markings
Look for clearly marked sizes that cover your instrument’s specified radius, including any sizes you expect to encounter on other guitars. Do not assume a set covers every common radius because it contains several pieces. For a compound-radius neck, one reading will not describe the entire fingerboard; check the appropriate positions and follow the instrument’s setup specifications.
Consider Handling and Kit Value
Readable markings and edges that sit cleanly against the measured surface matter more than the number of accessories. Metal gauges can be a durable workshop choice, but inspect any gauge for burrs before placing it near a finished instrument. If you also need to measure action or relief, a kit with a ruler and feeler gauges may be more economical than separate purchases. Those tools measure different things; they do not replace a radius gauge.
Who Should Buy Which Guitar Fretboard Radius Gauges?
Choose an understring set if your main goal is setting bridge-saddle height on assembled guitars. Choose notched gauges if you regularly assess fretted fingerboards. A compact set makes sense for occasional work when its listed sizes match your guitar. Choose a broader setup kit if you’re building a tool collection from scratch and will use its action ruler and feeler gauges. Whichever route you take, verify the radius against your instrument’s specifications rather than treating a gauge as a substitute for a complete setup.