Calculator Input
Slope Chart
The chart shows the horizontal run, vertical rise, and sloped surface line.
Example Data Table
| Use Case | Rise | Run | Percent Slope | Angle |
|---|---|---|---|---|
| Drainage line | 2 ft | 100 ft | 2% | 1.146° |
| Gentle ramp | 5 in | 100 in | 5% | 2.862° |
| Roof pitch | 6 in | 12 in | 50% | 26.565° |
| Road grade | 8 m | 200 m | 4% | 2.291° |
Formula Used
Percent slope: Percent slope = (Rise ÷ Run) × 100
Slope decimal: Slope = Rise ÷ Run
Angle: Angle = arctan(Rise ÷ Run)
Rise from percent: Rise = Run × Percent ÷ 100
Run from percent: Run = Rise ÷ (Percent ÷ 100)
Sloped length: Length = √(Rise² + Run²)
How to Use This Calculator
- Select a calculation method.
- Enter rise and run, coordinates, angle, or known grade values.
- Choose the correct units for each distance.
- Set the decimal precision.
- Press the calculate button.
- Review percent slope, angle, ratio, pitch, and converted units.
- Use the CSV or PDF button to save the result.
Understanding Percent Slope
What Percent Slope Means
Percent slope shows vertical change compared with horizontal distance. It is common in maths, construction, surveying, road design, drainage, roof layout, and ramp planning. A 5 percent slope means the surface rises 5 units for every 100 units of horizontal run. The units can be inches, feet, meters, or another length unit. The main rule is simple. Rise and run must be compared in the same base unit.
Why It Is Useful
Percent slope gives a fast way to compare different inclines. It is easier to read than a decimal slope in many field tasks. A decimal slope of 0.08 becomes 8 percent. That value is easy to discuss with builders, engineers, landscapers, and students. The value also helps estimate drainage direction. It can show whether a surface is too flat or too steep for a planned use.
Angle and Ratio View
This calculator also converts the slope into degrees and ratio form. The angle is measured from the horizontal line. The ratio shows one unit of rise against a matching run distance. For example, a 1 to 20 ratio means one unit rises over twenty horizontal units. Roof work may also use pitch per 12 units. A 6 in 12 pitch equals a 50 percent slope.
Practical Accuracy Tips
Measure horizontal run, not the sloped surface length. This is a common mistake. Use a level, tape, laser, or survey reading where possible. Convert units before comparing values. Small measurement errors can change the final percent on short runs. For long site work, collect several readings and compare the average. Always confirm local design rules before using slope values for safety-related work.
Reading the Result
Positive results mean the surface rises from start to end. Negative results mean the surface falls. A near zero value is almost level. Larger absolute values mean a steeper grade. Use the chart to view the rise and run visually. Use the table to compare the same result in percent, degrees, ratio, pitch, and distance units.
FAQs
1. What is percent slope?
Percent slope is rise divided by horizontal run, then multiplied by 100. It shows vertical change for each 100 units of run.
2. Is percent slope the same as angle?
No. Percent slope is a grade value. Angle is measured in degrees. The calculator converts between them using tangent and arctangent.
3. Can I use different units?
Yes. The calculator converts supported units before calculating. This helps when rise is in inches and run is in feet.
4. What does a negative slope mean?
A negative slope means the end point is lower than the start point. It shows a downward grade in the chosen direction.
5. How do I calculate slope from coordinates?
Use the coordinate method. The calculator subtracts start values from end values to find rise and run, then calculates grade.
6. What is a 5 percent slope?
A 5 percent slope rises 5 units for every 100 horizontal units. It is often considered a gentle to moderate grade.
7. Should I use sloped length as run?
No. Run means horizontal distance. Sloped length is the diagonal surface distance and is calculated separately from rise and run.
8. Can I download the results?
Yes. Use the CSV button for spreadsheet data. Use the PDF button for a simple printable result summary.