# Elevation Grade Calculator

URL: https://speedycalculator.com/calculators/construction/elevation-grade/
Last updated: 2026-10-25

> The elevation grade calculator finds the grade (slope) between two points as a percentage, angle and ratio from the change in elevation and horizontal distance, and the length along the slope.

## Inputs

- Elevation change (ft, m, in, yd, cm)
- Horizontal distance (ft, m, in, yd, cm)

## Results

- Grade
- Angle
- Ratio 1 :
- Fall per foot
- Slope length

## Formula

```
Grade = rise ÷ run × 100%
Angle = atan(rise ÷ run)
Ratio = 1 : run ÷ rise; slope length = √(rise² + run²)
```

## Explanation

Grade describes how steep a driveway, path, road, ramp or drain is. Driveways should usually stay below 12–15%, accessible walks below 5%, and drains and gutters need at least 1–2% fall. Surveyors and civil plans express grade as a percentage; landscapers often use a ratio like 1:20.

### How to use the Elevation Grade Calculator

- **Elevation change**
- **Horizontal distance**
- Every result field is editable: type into **Grade** and **Elevation change** plus every other field update to match.

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter the elevation change (rise or fall) and the horizontal distance. Type a grade into the result to find the elevation change it needs.

### Tips for an accurate estimate

- Measure angles with a digital angle finder or sliding bevel, not by eye.
- Make a test cut in scrap before cutting expensive stock.
- Small angle errors add up over many joints – check the first assembly before cutting the rest.
- Keep a written list of the dimensions and angles you set on the saw or machine.

### Common mistakes to avoid

- Reading the saw scale as the angle from the edge rather than from square.
- Rounding intermediate results too early.
- Mixing degrees and percent grade.

### Inputs explained

FieldWhat to enterElevation changeUnits: ft, m, in, yd, cmHorizontal distanceUnits: ft, m, in, yd, cm

### What each result means

- **Grade** = [Elevation change]÷[Horizontal distance]×100
- **Angle** = deg(atan([Elevation change]÷[Horizontal distance]))
- **Ratio 1 :** = [Horizontal distance]÷[Elevation change]
- **Fall per foot** = [Elevation change]÷[Horizontal distance]×12
- **Slope length** = sqrt([Elevation change]^2 + [Horizontal distance]^2)

### Example values

How the main result changes when **Elevation change** changes and everything else stays at the example values above:

Elevation change (ft)Grade (%)121.53242.553648

## Worked example

Inputs — Elevation change: 2 ft; Horizontal distance: 50 ft.

Results — **Grade = 4 %**; Angle = 2.291 °; Ratio 1 : = 25; Fall per foot = 0.48 in/ft; Slope length = 50.04 ft.

## FAQ

**What is a 2% grade?**
A fall of 2 ft over 100 ft, or about ¼ in per foot – a common minimum for drainage.

**How steep can a driveway be?**
Up to about 12–15% for most cars; steeper drives need special design for traction and scraping.

**Is grade the same as angle?**
No: 100% grade is 45°; 10% grade is 5.7°.

**What formula does the Elevation Grade Calculator use?**
Grade = rise ÷ run × 100%.