Canyon Size Calculator
Enter the rim width, floor width, depth and length of a canyon, plus a downcutting rate if you know it. The calculator models the canyon as a trapezoid and shows how much rock has gone, how steep the walls are and roughly how long a river would take to cut it.
- Rock volume removed
- Wall slope
- Time to cut
Measure the width from rim to rim at the top. Rates of 0.1 to 1 mm a year are typical for rivers cutting rock.
A canyon's size is mostly its depth and width. Treating the cross-section as a trapezoid, its area is the average of the rim and floor widths times the depth. Multiply by the length and you have the rock removed. A canyon 10 km across, 500 m wide at the floor and 1,000 m deep loses about 525 km³ of rock over 100 km.
Canyon volume chart
10 km rim, 500 m floor, 100 km long. Search for a depth.
| Depth (m) | Area (km²) | Volume (km³) | Wall slope |
|---|---|---|---|
| 100 | 0.53 | 52 | 1° |
| 250 | 1.31 | 131 | 3° |
| 500 | 2.62 | 262 | 6° |
| 750 | 3.94 | 394 | 9° |
| 1000 | 5.25 | 525 | 12° |
| 1500 | 7.88 | 788 | 18° |
| 2000 | 10.5 | 1050 | 23° |
Volume is rock removed.
Depth and volume
10 km wide at the rim. Slide the depth.
The cross-section shows the canyon walls and rock layers at the depth you choose.
How to estimate canyon size
From a map or a visit. Step through it.
Rim width
Edge to edge.
Topographic maps and online elevation tools give the rim height and river height, and the difference is the depth.
Gorge, canyon or valley
Shapes of cut land. Compare them.
Very narrow.
Steep sided.
Gentle sides.
Glaciers carve U-shaped valleys with flat floors, while rivers tend to cut V shapes and steep canyons.
Before you estimate
Data checks. Tick each item.
Tick each item as you go.
Rock layers erode at different rates, so wall slopes change with the rock and the volume is only a guide.
What you get
Canyon geometry. Each tile explains one result.
Cross-section.
Rock removed.
Wall angle.
Time to cut.
Depth to width.
Volumes in cubic kilometres help compare canyons of very different shapes.
Frequently Asked Questions
No question matches that search.
How do you calculate the volume of a canyon?
Work out the cross-section area as the average of the rim and floor widths times the depth, then multiply by the length.
How deep is a typical canyon?
Large canyons run from a few hundred metres to over a kilometre deep.
How fast do rivers cut canyons?
Usually between a tenth of a millimetre and a millimetre a year, though floods and soft rock can be much faster.
What is the difference between a canyon and a gorge?
A gorge is usually narrower and steeper than a canyon, but the words overlap.
How steep are canyon walls?
Most average between thirty and sixty degrees, with cliffs much steeper in hard rock.
Can I measure a canyon from a map?
Yes. Use contour lines or an elevation tool for the depth and measure the widths with the scale.
Why is the volume only an estimate?
Real canyons have side canyons, terraces and stepped walls that a simple shape leaves out.
Size up the landscape
A few measurements turn a view into numbers: how much rock has gone, how steep the walls are and how long it took.
More size calculators
Each one has its own calculator, worked examples and answers to common questions.