Cable Sag Calculator
Ideal small sag parabola uniform horizontal loadwL²/(8H), not catenary self weight, safe cable tension or support load. Actual independently established compatible SI units/model context; conditional arithmetic, not code compliance, engineering design or safe operation approval.
Description
A small-sag parabolic cable illustration assumes uniform load per horizontal span and established horizontal tension.
A small-sag parabolic cable illustration assumes uniform load per horizontal span and established horizontal tension.1
This tool calculates nominal sag under that model without substituting a self-weight catenary.
When to use Cable Sag Calculator
Use this tool to calculate nominal sag under that model without substituting a self-weight catenary.
How to use Cable Sag Calculator and how it works
- Prepare actualUniformLoadPerHorizontalMeter, actualSpanMeters, callerIndependentHorizontalTensionNewtons, with the units, conventions and assumptions below.
- Enter the required fields and run Cable Sag Calculator.
- Read result.value using the output definitions below.
- Correct any rejected inputs and rerun; interpret the result within the stated model and its assumptions.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| actualUniformLoadPerHorizontalMeter | Actual Uniform Load Per Horizontal Meter. Use the units and matching context stated in the calculation below. | number | Required; nonnegative; finite; other constraints below |
| actualSpanMeters | Actual Span Meters. Use the units and matching context stated in the calculation below. | number | Required; strictly positive; finite; other constraints below |
| callerIndependentHorizontalTensionNewtons | Caller Independent Horizontal Tension Newtons. Use the units and matching context stated in the calculation below. | number | Required; strictly positive; finite; other constraints below |
Supply nonnegative load per horizontal length in newtons per meter, positive horizontal span in meters and positive horizontal tension in newtons. Return w*L^2/(8*H) in meters under the symmetric parabolic approximation. This differs from an exact catenary model and does not solve tension from sag.
sagMeters=loadPerHorizontalLength*span^2/(8*horizontalTension) Apply the input ordering, units and branch conditions stated above.
| Output field | Meaning | Value type |
|---|---|---|
| result | Object containing the calculated or selected fields below. | object |
| result.value | Catenary parameter or parabolic sag in meters. | number |
{
"input": {
"actualUniformLoadPerHorizontalMeter": 1,
"actualSpanMeters": 4,
"callerIndependentHorizontalTensionNewtons": 1
},
"output": {
"result": {
"value": 2
}
}
}Limitations and assumptions
The calculation uses the supplied observations and model inputs. It does not collect measurements, select a reference population or coefficient, or establish that the model applies to the actual case. The stated branch conditions and output units remain part of the result.
All fields require explicit values. Unexpected fields, wrong types, nonfinite numbers and sparse arrays are rejected. Alignment, bounds and supported-token rules are explained above; extremely large inputs or nonfinite results can also fail. Input errors differ from successful false comparisons, unavailable-domain flags and empty match lists.
Alternative or Complementary methods
Use Holtrop Ship Resistance Approx Calculator for a complementary operation: Holtrop-Mennen resistance analysis requires a method edition, hull coefficients and a qualified flow regime.
Use Wave Force Cage Calculator for a complementary operation: A simplified wave-force model separates inertia and drag contributions along one direction.
References
-
Cable Sag Calculator — tool.io
Similar or alternative tools
- Holtrop Ship Resistance Approx Calculator
Holtrop-Mennen resistance analysis requires a method edition, hull coefficients and a qualified flow regime.
- Wave Force Cage Calculator
A simplified wave-force model separates inertia and drag contributions along one direction.