Evertune Tension Calculator

Your expert tool for calculating the perfect string tension for any guitar with an Evertune bridge.

Calculated Tension

16.20 lbs

Unit Weight
0.00000785 lb/in

Frequency
329.63 Hz

Evertune Module
Standard

What is an Evertune Tension Calculator?

An Evertune Tension Calculator is a specialized tool designed for guitarists who use the Evertune bridge system. It precisely calculates the pulling force (tension) of a guitar string based on its physical characteristics and tuning. This calculation is crucial because the Evertune bridge relies on a delicate balance of spring tension and string tension to maintain perfect tuning, regardless of playing style or environmental changes. By knowing the exact tension, you can ensure you have the correct Evertune saddle module installed for your preferred string gauge and tuning, guaranteeing flawless performance.

Evertune Tension Formula and Explanation

The calculation for string tension is based on principles of physics, specifically Taylor’s Law. The formula used by this calculator is a standard in string instrument engineering.

T = (UW * (2 * L * F)²) / g

This formula precisely determines the force required to bring a string to its target pitch. Understanding each component is key to mastering your guitar’s setup.

Variables Table

Variable	Meaning	Unit (Auto-Inferred)	Typical Range
T	Tension	Pounds (lbs) or Kilograms (kg)	10 – 28 lbs (for standard modules)
UW	Unit Weight	Pounds per linear inch (lb/in)	0.000005 – 0.000150 lb/in
L	Scale Length	Inches (in)	24.75″ – 30.0″
F	Frequency	Hertz (Hz)	60 Hz – 1300 Hz
g	Gravitational Constant	in/s²	386.09 in/s²

Practical Examples

Example 1: Standard Tuning Setup

A player wants to set up their Fender Stratocaster for standard E tuning with a regular set of ‘.010’ gauge strings. How much tension will be on the high E string?

• Inputs:
  • Scale Length: 25.5″
  • String Gauge: .010″
  • Tuning: E4 (329.63 Hz)
• Results:
  • Tension: Approximately 16.20 lbs
  • Evertune Module: Standard Tension (since 16.20 lbs is well within the 11-26 lbs range).

Example 2: Drop C on a Baritone Guitar

Another player is setting up their 7-string baritone guitar for a heavy Drop C tuning, using a .059 gauge string for the low C note.

• Inputs:
  • Scale Length: 27.0″
  • String Gauge: .059″
  • Tuning: C2 (65.41 Hz)
• Results:
  • Tension: Approximately 20.5 lbs
  • Evertune Module: Standard Tension. This is a perfect example where a heavy string on a long scale neck still falls within the standard module’s range due to the low tuning.

How to Use This Evertune Tension Calculator

1. Select Scale Length: Choose your guitar’s scale length from the dropdown. This is a critical measurement for tension.
2. Choose String Gauge: Select the specific gauge of the string you’re calculating for.
3. Set the Tuning: Pick the target note and octave for the string.
4. Choose Output Unit: Decide if you want to see the result in Pounds (lbs) or Kilograms (kg).
5. Review the Results: The calculator instantly provides the total tension. More importantly, it tells you the recommended Evertune module (Low, Standard, or High). Use this to confirm your setup is correct.
6. Analyze the Chart: The dynamic chart shows how tension would change if you chose a different gauge, helping you make informed decisions about your string sets.

Key Factors That Affect String Tension

• Scale Length: A longer scale length increases tension, assuming all other factors are equal. This is why baritone guitars feel “tighter.”
• String Gauge (Unit Weight): A thicker string has more mass (higher unit weight) and requires more tension to reach the same pitch.
• Tuning (Frequency): Tuning a string to a higher pitch (higher frequency) increases its tension significantly.
• String Core: The shape and material of the string’s core (e.g., round vs. hex core) can slightly alter its unit weight and flexibility, affecting final tension.
• Winding Material: For wound strings, materials like nickel-plated steel, pure nickel, or stainless steel have different densities, which changes the unit weight and therefore the tension.
• String Construction: The ratio of core-to-wrap wire on wound strings affects the final unit weight, making some brands feel stiffer or looser than others at the same gauge.

FAQ

What is “Zone 2” on an Evertune bridge?

Zone 2 is the ‘active’ or ‘sweet spot’ of the Evertune bridge where it maintains constant tension, keeping the string perfectly in tune. When you bend a string, you are temporarily pulling it out of Zone 2. Our calculator helps ensure your string tension keeps you firmly within the operating range of your module’s Zone 2.

Why do I need a specific Evertune module?

Evertune saddles contain springs designed to work within a specific tension range. A standard module works for ~11-26 lbs. If your tension is too low (e.g., light strings in a low tuning), you’ll need a Low Tension module. If it’s too high (heavy baritone strings), you’ll need a High Tension module. Using the wrong one can prevent the bridge from functioning correctly.

Can I use this calculator for bass guitars?

Yes, absolutely. As long as you know the scale length, string gauge, and target note, the physics are the same. Simply select the appropriate values. For example, choose a 34″ scale length and a .105 gauge string for a standard bass E string.

How accurate are the Unit Weight values?

The unit weight values in this calculator are based on industry-standard data from major string manufacturers like D’Addario. While there can be minor variations between brands, these values are highly accurate for general setup and module selection.

What happens if my tension is right on the edge of a module’s range?

Evertune recommends moving to the next module if you are within 2 lbs of a tension limit. For example, if your calculated tension is 11.5 lbs, which is technically in the standard range, it’s safer to use a Low Tension module for more reliable performance.

Does string ‘feel’ only come from tension?

No. While tension is the primary factor, string flexibility also plays a role. Strings with a smaller core relative to their wrap wire can feel more flexible even at the same tension as a string with a thicker core. However, tension is the metric the Evertune bridge operates on.

How do I find my guitar’s scale length?

Measure the distance from the front edge of the nut (where the string leaves the headstock) to the 12th fret. Multiply that number by two. This will give you your precise scale length.

Will this work for multi-scale (fanned-fret) guitars?

Yes, but you must perform a separate calculation for each string, entering the specific scale length for that individual string. For example, your low string might have a 27″ scale while your high string has a 25.5″ scale.