String Finder
Confirm the note, measure the vibrating length, and get a replacement recommendation.
Confirm the note
Measure vibrating length
Get a replacement recommendation
Advanced options (material, tension, comparison tools)
Advanced tool: back-calculate tension from known gauge
Chart Library
Community-maintained string charts. Each entry shows provenance and verification status. The library is in its early stages. More charts will be added as the community contributes data.
Available OpenHarp Charts
Select a chart to view the string table and provenance details.
Chart Builder
Build a working chart when an official chart is missing. The more measured vibrating lengths you enter, the more reliable the result.
Step 1:Define your harp
About & Method
The Mersenne-Taylor Law
Every vibrating string obeys the same fundamental physics:
Where:
- f = fundamental frequency (Hz), fixed by musical note
- L = vibrating string length (m), measurable with a ruler
- T = tension (N), target design parameter
- μ = linear mass density (kg/m) = ρ × π × (d/2)²
- ρ = material density (kg/m³), known for each material
- d = string diameter, what we solve for
Solving for d:
How to Measure Your Harp
You need one measurement per string: the vibrating length, from bridge pin to the lever blade (or nut on a stringed instrument without levers).
- Start from string #1 (highest/shortest)
- Hold a ruler parallel to the string
- Measure from bridge pin to the lever blade contact point
- Record in millimeters
- Repeat down to the lowest string
Tip: C strings are red, F strings are dark/black. Use a tuner to confirm notes.
Material Reference
| Material | Density (kg/m³) | Common use | Notes |
|---|---|---|---|
| Nylon monofilament | 1,140 | Folk / lever harps, treble + mid | Durable, affordable, widely available |
| Natural gut | 1,300 | Pedal harps throughout; some lever | Warm tone; humidity-sensitive |
| Fluorocarbon (KF) | 1,780 | Alternative to gut; all harp types | Stable in humidity; similar to gut in feel |
| Steel wire | 7,800 | Wire-strung / Celtic harps | Bright, metallic tone; high tension |
| Bronze / Brass wire | 8,600 | Wire-strung harps | Warmer than steel |
| Wound:copper on nylon | ~2,200 | Bass on folk harps (~G3 and below) | Custom-made; simple gauge formula doesn't apply |
| Wound:silver on gut | ~2,800 | Bass on pedal harps (~E3 and below) | Custom-made; contact a specialist supplier |
Public String Chart Links
Check whether a public chart already exists for your harp before building your own.
- Sylvia Woods Harp Center Printable String Lists - public chart hub with many maker/model links.
- Harp.com String Information - model guidance and replacement resources.
- Markwood Heavenly Strings - chart lookup and custom matching support.
Contribute
Help build an open string chart commons. Your measured data helps every other owner of the same model.
How to contribute
- Measure your strings (see About & Method → How to Measure Your Harp)
- Use the String Finder to verify the gauges make sense
- Email your measurements to us or submit them through our GitHub page
For technical contributors: Charts are stored as JSON files. See data/harps/lever/rees-harpsicle-26.json for an example format. Unknown fields go in as null. Partial data is always welcome.
String Suppliers
- Markwood Heavenly Strings - chart catalog and custom stringing analysis.
- Harp.com (Vanderbilt Music) - string selector and replacement resources.
- Vanderbilt Music Company - strings and gauges (pedal/lever).
- Bow Brand - gut, bass wire, and more.
- Musicmakers - lever harp replacement strings.
- Sylvia Woods Harp Center - replacement strings, sets, and supplies.
Harp Profiler
Use this when you want better-than-default accuracy. Measure a few existing strings with a caliper, and OpenHarp estimates your harp's working tension so Finder/Builder match your instrument more closely.