Open Pit Bench Design Checker Mining Tools
Open pit geometry
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Open pit geometry

Open Pit Bench Design Checker

Calculate the overall slope angle from bench height, berm width, face angle, and bench count.

Compare the result with a target angle, see the safe / near / danger status, and preview the section in the browser.

Auto-calculate the section geometry Show safe / near / danger at a glance Switch between metric and imperial
How to use

Safety notice

  • This is a geometry checker, not a substitute for geotechnical stability analysis or rockfall analysis.
  • It checks the consistency of bench height, berm width, face angle, and overall slope angle, but it does not judge legal compliance.
  • If the target comparison is near or on the danger side, always have a geotechnical reviewer confirm the design.
  • Water, blast damage, rock quality, equipment width, and drainage conditions are not part of this tool.

How to use

  1. 1 Enter bench height, berm width, face angle, and bench count.
  2. 2 Add a target overall slope angle if you want to compare the design against a reference angle.
  3. 3 Choose metric or imperial, then open Settings if you want to change precision or sharing behavior.
  4. 4 Review the overall angle, the target margin, the exact-match values, and the previewed cross-section.
  5. 5 Use Copy result, Copy share URL, Reset, or the recent list to reuse the same condition later.

Sample

12 m bench, 8 m berm, 70° face, 4 benches

Input: Bench height 12 m, berm width 8 m, face angle 70°, bench count 4, target overall slope angle 45°
Output: Overall slope angle 49.2°, margin -4.2°, required berm width 10.2 m, danger side

The same geometry in imperial

Input: Bench height 39.37 ft, berm width 26.25 ft, face angle 70°, bench count 4, target overall slope angle 52°
Output: Overall slope angle 49.2°, margin +2.8°, safe side

FAQ

Is the angle measured from the horizontal?

Yes. Both the bench face angle and the overall slope angle are measured from the horizontal.

What happens when berm width is 0?

The overall angle moves closer to the face angle, but the tool still warns you because that is rarely practical in the field.

What if the target angle cannot be matched exactly?

The required berm width or required face angle can fall outside a workable range. In that case the exact-match helper shows that the target is not achievable with the current geometry.

Does this include local regulations or safety standards?

No. The tool stays limited to geometry and unit conversion so that it can be used globally without embedding local rules.

Can I work in both metric and imperial units?

Yes. The unit switch converts the bench height and berm width while keeping the geometry and the formulas the same.

Glossary

Bench height

The vertical height of one bench.

Berm width

The horizontal width between benches.

Face angle

The face angle measured from the horizontal.

Overall slope angle

The angle of the whole bench stack when you look at the section from crest to toe.

Face setback

The horizontal run of one bench face.

Formulas

  • map[Text:face_run = h / tan(a) text:face_run = h / tan(a)]
  • map[Text:total_height = h × n text:total_height = h × n]
  • map[Text:total_run = (face_run × n) + (w × max(n - 1, 0)) text:total_run = (face_run × n) + (w × max(n - 1, 0))]
  • map[Text:overall_angle = atan(total_height / total_run) text:overall_angle = atan(total_height / total_run)]
  • map[Text:margin = target - overall_angle text:margin = target - overall_angle]
  • map[Text:required_berm_width = (total_height / tan(target) - n × face_run) / (n - 1) text:required_berm_width = (total_height / tan(target) - n × face_run) / (n - 1)]
  • map[Text:required_face_run = (total_height / tan(target) - (n - 1) × w) / n text:required_face_run = (total_height / tan(target) - (n - 1) × w) / n]
  • map[Text:required_face_angle = atan(h / required_face_run) text:required_face_angle = atan(h / required_face_run)]

Notes

  • This tool does not cover water, blasting, rock quality, or equipment clearance.
  • If the target comparison is near the threshold, do not rely on rounding alone to make the decision.
  • If your site has a regional standard or company standard, follow that first.
  • Use this for geometric checks only. A real slope design still needs a geotechnical review.
Overall slope angle
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Fix the highlighted inputs to recalculate.