Calculators › Slope

Slope Calculator

Convert between slope percentage, ratio, degrees, and rise/run. Enter any one value.

Enter One Value

For estimation purposes only. Terms of Use

Conversions

percent (%)
Degrees
Ratio (1:X)
Rise per 10m run
Classification

Formula Used

Slope % = (Rise ÷ Run) × 100
Degrees = arctan(Rise ÷ Run)
Ratio = 100 ÷ Slope %

Worked Example

A rise of 0.5m over a 20m run:

Slope % = (0.5 ÷ 20) × 100 = 2.5%
Degrees = arctan(0.025) = 1.43°
Ratio = 1:40

When to Use This Calculator

Use this when checking drainage slopes, setting grades, verifying drawing specifications, or converting between the different ways slope is expressed across various drawings and standards.

When Not to Use This Calculator

This does not replace a survey or formal grading plan. For final grade certification, use surveyed elevations and proper engineering review.

Frequently Asked Questions

What's the minimum slope for drainage?

Typically 0.5-1% minimum for positive drainage on paved surfaces, though this varies by local standards and the type of surface.

What does a 1:40 ratio mean?

It means for every 40 units of horizontal distance (run), there is 1 unit of vertical rise. This equals a 2.5% slope.

How steep is too steep for a cut slope?

Depends entirely on soil type. Common earth is often cut at 1:1 (45°), while rock can be much steeper. Always follow a geotechnical recommendation for cut slopes.