Evertune Calculator

What is an Evertune Bridge?

The Evertune bridge is a revolutionary, all-mechanical guitar bridge system that uses a patented spring and lever system to keep a guitar in tune indefinitely. Unlike traditional bridges or electronic tuners, the Evertune works by maintaining constant tension on each string. Each saddle is part of a module that floats, balancing the pull of the string against an internal spring. When string tension changes due to factors like temperature, humidity, aggressive playing, or string stretching, the saddle pivots to compensate, instantly correcting the pitch. This makes it a game-changer for touring musicians and recording artists who demand perfect tuning stability. An Evertune calculator is an essential tool for setting up this bridge correctly.

This system is for any guitarist who prioritizes perfect intonation and tuning stability above all else. Common misconceptions are that the Evertune feels unnatural or prevents string bending. In reality, the bridge can be set to allow for normal bending and vibrato techniques while still keeping the open note perfectly in tune. Using an Evertune calculator helps find the perfect balance for your playing style.

Evertune Calculator: Formula and Mathematical Explanation

The core of any string tension tool, including this Evertune calculator, is based on the physics of a vibrating string. The formula to calculate tension is derived from Taylor’s Law and is provided by string manufacturers like D’Addario. It allows us to predict the pull a string will exert when tuned to a specific pitch on a guitar with a specific scale length.

The formula is: T = (UW * (2 * L * F)²) / 386.4

This calculation is crucial for the Evertune system, as the bridge’s internal springs must counteract this tension. Our Evertune calculator automates this complex math for you. Here’s a step-by-step breakdown:

Scale Length (L) and Frequency (F) are determined from your input.
These are multiplied (2 * L * F) and then squared.
This result is multiplied by the Unit Weight (UW) of the selected string.
Finally, the total is divided by a gravitational constant (386.4) to yield the tension in pounds.

Understanding this formula is the first step to mastering your instrument’s setup. For more details on finding the right strings, see this guide on choosing the right guitar strings.

Variables in the String Tension Formula
Variable	Meaning	Unit	Typical Range
T	Tension	Pounds (lbs)	10 – 28 lbs per string
UW	Unit Weight	lbs/inch	0.000006 to 0.000200
L	Scale Length	Inches	24.75″ – 27″
F	Frequency	Hertz (Hz)	82 Hz (E2) – 330 Hz (E4)

Practical Examples (Real-World Use Cases)

Let’s explore how our Evertune calculator can be used in two common scenarios.

Example 1: Standard Tuning to Drop D

A player with a 25.5″ scale guitar wants to switch from E Standard (EADGBe) with a .046 gauge low E string to Drop D (DADGBe), but wants to maintain a similar feel.

Input:

Scale Length: 25.5″
String 6 Note: D2 (from E2)
String 6 Gauge: (to be determined)

Evertune Calculator Output: The calculator shows that the .046 string’s tension drops from ~17.5 lbs at E2 to ~13.8 lbs at D2, feeling very loose. To get back to a similar tension, the calculator suggests moving to a heavier gauge, like a .052, which would have around 17.7 lbs of tension in D2. This ensures the Evertune module operates in its ideal range.

Example 2: Setting up a 7-String for Low Tuning

A metal guitarist has a 26.5″ scale 7-string and wants to tune to Drop A (AEADGBe) using a .059 gauge for the low A.

Input:

Scale Length: 26.5″
String 7 Note: A1
String 7 Gauge: .059

Evertune Calculator Output: The Evertune calculator computes the tension for the low A string to be approximately 18.2 lbs. This is well within the ~10-28 lbs range of the standard Evertune saddle modules, confirming the player doesn’t need a special high-tension module for this setup. This is critical information to have before buying strings or parts.

How to Use This Evertune Calculator

This Evertune calculator is designed for ease of use while providing the detailed data needed for a professional setup. Follow these steps:

Enter Scale Length: Start by inputting your guitar’s scale length in inches. This is the most critical measurement for accurate tension calculation.
Select Tuning and Gauge for Each String: For each of the six strings, use the dropdown menus to select your desired note (frequency) and string gauge (which corresponds to a specific unit weight).
Analyze the Results in Real Time: As you make changes, the calculator will instantly update the Total Tension, individual string tensions in the table, and the visual tension curve in the chart.
Check Key Metrics: The primary result shows the total pull on your guitar’s neck. The intermediate values provide the average tension, highest tension string, and a recommendation for the Evertune module type. Standard modules work for most setups (10-28 lbs), but very high tension might require a high-tension module.
Use the Table and Chart: The table gives you a precise pound-for-pound breakdown, perfect for fine-tuning your setup. The chart provides a quick visual reference to ensure a smooth and balanced tension curve across the strings. An uneven curve can lead to an inconsistent playing feel. For further reading, an intonation adjustment guide can be very helpful.

Key Factors That Affect Evertune Calculator Results

The output of this Evertune calculator is influenced by several interconnected factors. Understanding them will help you achieve the perfect setup.

String Gauge: This is the thickness of the string and directly impacts its mass (Unit Weight). Heavier gauges produce more tension at the same pitch, resulting in a tighter feel and often a fuller tone, but are harder to bend.
Tuning (Pitch): Higher pitches require more tension for the same string, while lower pitches require less. This is why a dedicated Evertune calculator is vital when exploring alternate tunings.
Scale Length: A longer scale length increases the distance the string must stretch, resulting in higher tension for the same pitch and gauge. This explains why baritone guitars have such high tension. You can learn more about the scale length impact on tone.
String Material: Different materials (e.g., nickel-plated steel, pure nickel, stainless steel) have different densities. Our calculator uses standard D’Addario nickel-wound unit weights, but be aware that other brands or materials may vary slightly.
Core-to-Wrap Ratio: On wound strings, the ratio of the inner core wire to the outer wrap wire affects the string’s flexibility and unit weight. This is a subtle but important factor in how a string feels.
Player Preference: Ultimately, the ideal tension is subjective. Some players prefer a “slinky” feel with lower tension, while others want the resistance of a high-tension setup for aggressive rhythm playing. This Evertune calculator gives you the objective data to achieve your desired subjective feel.

Frequently Asked Questions (FAQ)

1. What is “Zone 2” on an Evertune bridge?

Zone 2 is the active range where the Evertune system maintains constant tension. When you turn the tuning peg at the headstock in Zone 2, the pitch doesn’t change because the saddle moves to compensate. This is the state your guitar must be in for the Evertune to work correctly. Our Evertune calculator helps ensure your chosen strings can operate effectively in this zone.

2. Can I still bend strings with an Evertune?

Yes. You can set the bridge to allow for string bending. This is typically done by setting the saddle to the very “edge” of Zone 2, where a small amount of extra pull from a bend will cause the pitch to go sharp, just like a normal bridge.

3. Do I need special strings for an Evertune?

No, you can use any standard electric guitar strings. However, because tuning is so stable, you may find that strings last longer. Using an Evertune calculator helps you select the right gauges from any brand.

4. Why does my total tension matter?

Total tension is the combined force all strings exert on your guitar’s neck. A significant change in total tension (e.g., switching from 9s to 12s) can affect the neck’s relief (bow) and may require a truss rod adjustment. This is a key metric our Evertune calculator provides.

5. What if my calculated tension is too high or low?

Evertune saddles have an optimal tension range (typically 10-28 lbs for standard modules). If the Evertune calculator shows your desired tuning and gauge results in tension outside this range, you may need a different saddle module (e.g., Low or High Tension) or you should adjust your string gauge.

6. How does scale length affect my choice?

A longer scale length requires more tension to reach the same pitch. If you switch from a 24.75″ scale guitar to a 25.5″ scale guitar, you might need to use slightly lighter strings to achieve the same playing feel, a fact our Evertune calculator can help you quantify.

7. Is installation of an Evertune bridge reversible?

Installation requires routing a significant cavity in the guitar’s body, so it is a permanent modification and not easily reversible. It’s a serious upgrade and using an Evertune calculator beforehand is part of the essential planning process.

8. How accurate is this Evertune calculator?

This calculator is highly accurate as it’s based on the industry-standard string tension formula and D’Addario’s unit weight specifications. However, slight variations can exist between string brands. It should be used as a powerful guide for making informed decisions.

Related Tools and Internal Resources

Guitar String Tension Calculator

A more general tool for calculating tension on any type of bridge, not just an Evertune.
Intonation Adjustment Guide

Learn the principles of setting your guitar’s intonation for perfect tuning up the neck.
How to Set Up a Floating Bridge

A guide for traditional floating tremolo systems, a useful comparison to the Evertune’s concepts.
Guitar Maintenance Tips

Discover essential tips for keeping your instrument in top playing condition.
Choosing the Right Guitar Strings

An in-depth look at how materials, gauges, and windings affect your tone and feel.
Scale Length Impact on Tone

Explore how scale length influences string tension, feel, and the overall voice of your guitar.