Rip Rap Calculator

UKM APPS

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About this app

Rip Rap Calculator works out, in seconds, how many tons of armour stone, bedding and filter fabric it takes to line a sloping bank against erosion. Enter the bank length, the slope height and the slope ratio, pick your gradation class, and read the order quantity straight away. It works completely offline and nothing you enter ever leaves your phone.

HOW IT WORKS
The app follows the standard erosion-control method, on the slope face rather than the flat plan area:

1. Rip rap covers the face of the bank, not its footprint. For a slope stated as Z:1 (Z feet horizontal per 1 foot vertical) and a vertical height H, the face is H x the square root of (1 + Z squared) long. On a 2:1 bank that is about 12 percent more surface than the plan projection, so measuring flat under-orders the stone.

2. Slope face area is the bank length multiplied by that face length.

3. Stone is specified by D50, the median size: half the mixture by weight is larger. A well-graded mix runs up to a largest stone D100 of about 1.5 x D50.

4. The armour layer is 1.5 to 2 times D50 thick, and never thinner than 6 inches. USACE EM 1110-2-1601 sizes it to the greater of D100 and 1.5 x D50; erosion-control manuals ask for 2 x D50 where a filter layer is used. A slider lets you set the factor.

5. Volume is the slope face area times the thickness, converted to cubic yards. Weight uses the placed density of rip rap, voids included, around 105 pounds per cubic foot or roughly 1.42 US tons per cubic yard.

6. Under the armour goes a bedding or filter course, at least 6 inches thick, plus geotextile with an allowance for seam overlap. The app sizes both.

A 100 ft bank 8 ft high on a 2:1 slope has a 17.89 ft face and 1,788.85 sq ft of surface. Armoured with a Type M class (D50 12 in) at 2 x D50, the layer is 24 in thick: 132.51 cubic yards, 187.83 US tons of stone, plus 44.72 tons of bedding and 1,968 sq ft of geotextile.

WHAT YOU CAN DO
- Enter bank length, slope height and slope ratio, or type a slope-face area directly
- Set the stone D50, the placed density, the bedding depth and your truck capacity
- Slide the armour thickness from 1.5 to 2.5 times D50 and watch the tonnage move
- Read tons, cubic yards, tonnes, cubic metres, truckloads, bedding stone and geotextile at once
- Check your stone size against a design velocity with the Isbash equation
- Open Details for a step-by-step breakdown and a table of gradation classes, Type VL to Type VH, costed in tons for your own slope
- Learn the sizing, the thickness rule and why the filter layer matters, in plain language

BUILT FOR CLARITY
A rose-stone design puts the big tonnage first, with the supporting figures right beside it. US customary units lead, with metric alongside the headline. Light and dark themes, a tiny download, no clutter and no account required.

AN ESTIMATE, NOT AN ENGINEERED DESIGN
Rip rap revetments are hydraulic and slope-stability works with real safety and property consequences. This app estimates quantities for a straight, uniform bank; it does not size a revetment. It leaves out toe keys, crest anchoring, scour depth, launch aprons, wave and boat-wash loading, ice, bends, bank soil and local permit requirements. It is NOT a substitute for a licensed civil, geotechnical or hydraulic engineer, and it is not an approved design. Always confirm the gradation class, layer thickness, filter design and final quantities with your engineer and your quarry before ordering.

PRIVACY
The app collects no personal data and works fully offline. Ads are served by Google AdMob, which may use an advertising identifier as described in Google's policies.

Download Rip Rap Calculator and get a quick, sensible picture of the armour stone your bank will take.

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Rip Rap Calculator