Bass strings use much larger wound constructions than guitar strings, so exact manufacturer unit weights are especially valuable. This calculator provides a consistent comparison model for standard, short, long, and custom-scale bass setups.
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Key takeaways
- Use the calculator to compare setups; use manufacturer unit weights when exact product tension is available.
- The same bass string has about 22% less theoretical tension at 30 inches than at 34 inches.
- Build a set string by string instead of assuming one gauge label creates an even profile.
- Check winding length, taper position, relief, action, and intonation after a major change.
How to use this: Use these recommendations to compare options, then check the final set against the string maker's specifications and confirm that it suits your instrument.
Quick answer
Compare bass strings by unit weight and scale, not gauge alone
Bass strings with the same outside diameter can have different cores, wraps, tapers, and unit weights. Use the calculator to compare a known set with a proposed scale or tuning, then prefer manufacturer tension data when a final product decision depends on exact construction.
Record all gauges, scale, and tuning before changing anything.
Short, long, extra-long, and multiscale basses differ materially.
Outside gauge cannot reveal proprietary unit weight.
How to use the bass string tension calculator
Model the bass exactly as played, including the low-B or high-C string when present. Save the per-string profile before comparing another tuning, scale, or set.
- Choose four, five, or six strings and enter the exact open-note octaves.
- Enter the speaking scale or the per-string multiscale lengths.
- Record every gauge and construction note available from the package.
- Change one variable and compare per-string tension rather than total pull alone.
- Verify the final set’s winding length, taper, and manufacturer data.
Worked example: taking a .105 low E down to D
E1 to D1 is a whole step, and the ratio is the same one that governs any whole-step drop on a fretted string: about 79.4% of the former tension survives. What changes on a bass is the raw diameter involved — restoring that pull on a .105 takes roughly .013 inch of added gauge, more total wire than a guitar's .046 low string moves through the same percentage.
| Low string | Pitch | Purpose |
|---|---|---|
| .105 | E1 | Original reference |
| .105 | D1 | About 20.6% less pull |
| .115 or .120 | D1 | Sold sizes to compare against the target |
Bass construction differences can outweigh a small gauge difference, so use product unit weight when available.
Read tension alongside stiffness and fit
A numerically matched bass string can still bend, speak, or intonate differently because stiffness is not the same as static tension. Treat the result as one setup measurement rather than a complete tone prediction.
- Inspect the low B or dropped string separately from the upper set.
- Check taper location and winding length before choosing extra-long strings.
- Verify bridge and tuner clearance for large gauges.
- Recheck relief, action, pickup height, and intonation after installation.
Interpreting bass tension targets
A standard 45–105 four-string set at 34 inches works out to roughly 39 to 48 pounds-force per string — a reasonable reference range, though the useful target still depends on scale, construction, action, technique, and pickup response. Treat the numerical profile as a way to compare two setups rather than a universal definition of light or heavy.
The current balance labels are guitar-oriented and should not override the individual bass values shown in each row. Focus on relative changes and total pull.
| Comparison question | Keep fixed | Change |
|---|---|---|
| Match feel after tuning down | Scale and target tension | Gauge / unit weight |
| Compare short and long scale | Pitch and string construction | Scale length |
| Build an even set | Desired response range | Each string independently |
| Estimate neck-load change | Instrument and tuning | Sum of all string tensions |
Short, long, and extra-long scale bass
A 30-inch short-scale bass has about 22% less theoretical tension than a 34-inch bass with the same string and pitch. A 35-inch scale has about 6% more than a 34-inch scale. Those differences help explain why identical printed gauges can respond differently across instruments.
Why bass construction data matters
A .105 roundwound, flatwound, pressurewound, and taperwound string can have a different core-to-wrap ratio and therefore a different unit weight. Outside diameter alone cannot identify exact tension.
Use manufacturer tension or unit-weight tables when selecting a specific set. Use Guitar String Tension Calculator to explore relative changes when consistent product data is not available.
Applying a new bass set safely
Large changes in total pull can alter relief and action. Taper length must also place the full-diameter portion correctly across the nut and speaking length. Confirm bridge, nut, and tuner compatibility before installing unusually large strings.
- Measure scale length at the speaking length, not total string length.
- Check winding length before buying for through-body or extra-long bridges.
- Adding a low B to a neck built for four strings can need more truss-rod correction than the upper strings alone would suggest.
- A heavier low string can shift where it sits over the pickup poles — recheck alignment, not just clearance.
Reference material
Technical references
Use these manufacturer references when you need product-specific tension or setup information. They were last reviewed on ; the gauge suggestions on this page remain starting points because strings and instruments vary.
Before you change strings
Save your current setup, change one variable at a time, and recheck tuning, neck relief, action, and intonation after the new strings settle. If a result looks inconsistent with your instrument or a manufacturer's data, send the setup details through the contact page.