Calculator
Example data table
| Scenario | Point A | Point B | Run A→B | Grade (%) | Use case |
|---|---|---|---|---|---|
| Gentle path | 102.00 | 101.00 | 20.00 | -5.000 | Comfortable walking slope with light drainage. |
| Swale fall | 100.50 | 100.20 | 15.00 | -2.000 | Guides surface water toward a planting basin. |
| Terrace break | 103.00 | 101.50 | 10.00 | -15.000 | Often needs steps, edging, or terracing. |
Formula used
- Rise: rise = elevation₂ − elevation₁
- Grade (%): grade = (rise / run) × 100
- Angle (degrees): angle = arctan(rise / run) × (180/π)
- Slope ratio (1:n): n = run / |rise| (if rise is zero, ratio is infinite)
- Grade change (two segments): Δgrade = grade₂ − grade₁
How to use this calculator
- Select a unit system and keep all inputs consistent.
- Enter Point A elevation, Point B elevation, and the horizontal run A→B.
- Optional: enable Segment 2, then enter Point C elevation and run B→C.
- Press Calculate to show results above the form.
- Use the CSV or PDF buttons to save the latest report.
Grade and runoff direction in planting areas
Small grade changes steer water across soil surfaces and mulched corridors. A steady fall of about 1–2% can move water away from stems, prevent puddling, and protect structure after irrigation. When grade is near zero, fine particles settle, pores close, and infiltration slows. Use the calculator to confirm that a swale base, path edge, or bed shoulder keeps a clear flow direction. Mark control points with stakes onsite so future adjustments easily keep the same reference line across seasons yearly.
Erosion risk on steeper garden slopes
As percent grade increases, runoff velocity rises and soil shear increases. Slopes above roughly 8% often need groundcovers, jute mesh, stone, or check dams. Where grade changes abruptly, rills commonly form at the break point. Comparing Segment 1 and Segment 2 shows where a transition strip, landing, or rock apron will reduce scouring.
Path comfort, access, and maintenance
Path performance depends on grade and surface material. Gravel, bark, and compacted fines handle mild grades, but traction drops as slopes grow. A smoother grade change lowers slip risk and reduces material migration during rain. Angle output helps visualize steepness, while the 1:n ratio supports quick field checks using a level and tape. Steeper grades need more edging and more frequent resurfacing.
Terracing and retaining layout decisions
Terraces reduce slope by converting one long run into short rises with flat benches. Use rise and run outputs to estimate how many benches are needed to keep each segment within a target grade. Consistent segment grades simplify string lines and reduce cut-and-fill errors. Flatter benches improve root-zone moisture uniformity and nutrient retention.
Survey inputs and quality control
Reliable elevations are the foundation of useful grade calculations. Take readings from a laser level, water level, or calibrated inclinometer, then recheck at least one point for repeatability. Record horizontal run as plan distance, not sloped surface length. After construction, spot-check finished grades to verify drainage intent near hardscape, raised beds, and downspout outlets.
FAQs
1) What does percent grade represent?
Percent grade is rise divided by run, multiplied by 100. A negative value means the surface falls from the first point to the second.
2) Which distance should I use for run?
Use horizontal plan distance measured on the ground plan, not the sloped surface length. A tape plus level line, or a map measurement, works well.
3) Why enable a second segment?
Two segments capture a slope break, such as a path meeting a terrace. The calculator then reports the change in grade between segments to highlight abrupt transitions.
4) What grades suit typical garden paths?
Many walking paths feel comfortable around 0–5% when surfaced properly. Above that, traction and erosion control become more important, especially in loose gravel or mulch.
5) How does grade affect raised bed drainage?
Grade influences where water collects and how quickly it leaves the bed edges. A small fall away from the bed reduces pooling at the base and helps protect timber and soil structure.
6) When is the angle output useful?
Angle helps you visualize steepness and compare slopes quickly. It is also handy when matching a planned slope to tool readings from an inclinometer or angle finder.