KEVOS® MAKEOS · Geometry
Linear Interpolation
What value lies between these two table entries?
Straight-line interpolation (or extrapolation) between two known points, in either direction, for reading engineering tables and charts.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Find | choice | Interpolate forwards (y from x) or backwards (x from y). |
| First point x₁ | x value of the first table row. | |
| First point y₁ | Value at x₁. | |
| Second point x₂ | x value of the second table row. | |
| Second point y₂ | Value at x₂. | |
| Known x | The x value you need (forward mode). | |
| Known y | The y value you need (backward mode). |
Method and formulas
- y = y₁ + (x − x₁)(y₂ − y₁) ÷ (x₂ − x₁).
- x = x₁ + (y − y₁)(x₂ − x₁) ÷ (y₂ − y₁).
- Example: between (20, 4.18) and (40, 4.179), x = 25 gives y = 4.17975.
Limitations
- Assumes a straight line between the points; strongly curved data needs closer points or another method.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Read a value between two rows of a data table
- Find the input that gives a target output
- Check a chart reading
Who it is for
- Engineers
- Technicians
- Estimators
What you get
- Interpolated value
- Slope
- Whether the point lies inside the table range
Interpreting the result
- Avoid extrapolating far beyond the table; the relation may change.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 121. Topic reference; no source tables or recommended settings are reproduced.
WORKOS tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.
