Build cleaner borders with confident retaining edges. See exposed lip, buried depth, and material suggestions. Export results for crews, quotes, and quick site checks.
| Scenario | Grade change | Cover depth | Visible lip | Embedment |
|---|---|---|---|---|
| Raised bed border | 120 mm | 40 mm | 20 mm | 90 mm |
| Paver edge restraint | 60 mm | 10 mm | 15 mm | 75 mm |
| Mulched tree ring | 80 mm | 60 mm | 10 mm | 80 mm |
Use the table to sanity-check your inputs before calculating.
The calculator estimates an edging height that resists soil and mulch pressure while keeping a clean visible line.
Measure grade change as the vertical difference the edging must resist. Add cover depth for mulch or soil that presses against the border, then include a small visible lip so the top line stays clean after settlement. The calculator combines these to estimate exposed height, which drives both the total edge height and the material stiffness you should select for long, straight runs on slopes and paths.
Embedment is the buried portion that prevents tipping and creep. For typical garden borders, a practical rule is to bury at least about 35% of the exposed height, increasing in loose sand or when wheelbarrows, mowers, or foot traffic load the edge. If you enter a smaller embedment, the calculator recommends the higher value to maintain stability and reduce seasonal movement, especially along long curves.
Safety factor accounts for uncertainty in compaction, moisture, and freeze–thaw cycles. A modest allowance of 5–15% often covers light settling and minor regrading, while higher values suit newly placed soils or heavy rainfall zones. Apply the factor to the combined exposed height plus embedment, producing a total edge height that remains functional even when the soil profile changes during the year and during irrigation soak periods.
Stake spacing affects alignment and long-term performance. Taller edges and softer soils need closer stakes to resist bending and joint rotation; dense clay and short edges can tolerate wider spacing. The calculator converts your soil and load selections into a suggested spacing range, then estimates stake count from border length. Use this guidance to plan hardware, minimize visible waviness, and keep corners tight near gates and entrances.
Material estimation improves purchasing accuracy. Enter border length, piece length, and waste percentage to compute pieces required for straight segments, curves, and offcuts around beds. Combine this with the calculated edge height to choose a profile that matches the required depth and visible finish. Recording results and exporting CSV or PDF makes it easy to compare scenarios for different beds before ordering.
It is the exposed height needed at the surface plus the recommended embedment below grade, then adjusted by the safety factor. It helps you pick an edging profile that will still perform after settling.
Use a straight board and level, a laser level, or a string line. Measure the vertical difference between the high side grade and low side grade across the border line where the edge will sit.
Loose soils provide less lateral support, so the edge can lean or creep outward. More embedment improves resistance to overturning and keeps stakes and joints loaded more evenly over time.
For compacted, established beds, 5–10% is usually reasonable. For fresh backfill, high rainfall, or freeze–thaw areas, 10–20% gives extra tolerance for settlement and seasonal movement.
Expect more waste on tight curves and many corners. Increase the waste percentage, use shorter piece lengths where possible, and place stakes closer at direction changes to prevent joints opening.
If the retained height is large, the edge supports hardscape loads, or you have poor drainage and saturated soils, treat it as a structural wall. Consult a qualified professional for site-specific design.
This tool provides planning guidance for typical garden edging and small retaining borders. For tall or structural retaining walls, consult a qualified professional for site-specific design.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.