Calculate rip rap tonnage, armour depth and delivered cost for the bank you are armouring.
Bank Dimensions
Stone to order
5.30
tons of limestone rip rap, 3 to 6 in, laid 6 in thick over 200 sq ft.
Freight runs at $5 per mi with a $75 minimum. Geotextile, excavation, machine hire, permits and labour are all extra. Estimates only, not engineering advice, and a waterway job wants a licensed civil engineer on the hydraulics.
Last updated August 5, 2026 by our expert review team.
Armour section
Rip rap is not decorative stone, it is armour, and an armour layer has to be deeper than the rock it contains. Lay 6 to 10 in stone in a 4 in layer and the big pieces sit proud of the face, rock under load, and work out one at a time until there is a hole. The section below is drawn from the depth and the gradation you set above.
Layer and stone share one scale, so the stones really do stand that far out when the depth is short. Slope grade lives in the bank options on the calculator, and this is the mild (< 2:1) band.
One course fits, but only just. Another 0.8 in of depth reaches the 1.5x median-stone thickness this page quotes in its FAQ, which is where a face stops being a single layer of loose rock.
All four rows use the 6 in layer you entered. Where a gradation says no, the layer cannot fit one full course of its largest stone, which is geometry rather than a specification.
Priced banks
All three run through the same lines as the calculator and are priced at the $35 per ton and 15 mi haul you set above, so you can type any of them in and get the same answer back.
Pond shoreline
7.33
tons of stone
$332 delivered
Short run with easy access from the top of the bank. Fabric down first, then stone tipped off the tailgate and raked into place by hand.
Creek bank
46.46
tons of stone
$1,701 delivered
Permit job, machine job. The toe course goes in below the streambed, because a face keyed at grade walks downstream in the first flood.
Drainage ditch
14.83
tons of stone
$594 delivered
Long and thin, so the fabric seams matter more than the stone does. Lap them uphill and weight each one as you unroll.
Every depth above was set to clear the thickness test in the section at the top of the page, which is why the ditch is 7 in deep and not 6. Stone and freight only. None of the three includes fabric, excavation or a machine.
Bank practice
Not a sequence, so not numbered. Each one is a habit that separates a face still tight after ten winters from one with stone piled at the toe.
Order stone by its gradation, not by the word "rip rap". A quarry ticket that says 6 to 10 in is a specification; one that says "big rock" is a gamble on whatever is closest to the loader that morning.
Do not exceed a 2:1 slope without an engineering review. Steeper faces want 12 to 18 in stone and a buried key trench at the toe, at least 2 ft deep, or the whole face creeps downhill.
Lay non-woven geotextile under every square foot of it. Fines pumping up through the voids is the single most common reason a bank that looked right for two winters has stone sitting in a hollow by the fifth.
Check permits before anything touches the water. EPA erosion control requirements and a Section 404 permit can run 3 to 6 months and $200 to $2,000.
Buy 15 to 20% over on anything steeper than 3:1. Voids swallow 30 to 40% of the volume and the face settles another 5 to 10% in its first year, and both come off the top of the layer.
Angular quarry stone only. Rounded river cobble rolls, and interlock is the entire mechanism holding a revetment together. Send rounded stone to the river rock calculator and keep it out of the bank.
Gradation and density
Length by width by depth gives a volume, and the gradation and rock type turn that volume into weight. Bigger stone weighs less per cubic yard, because bigger stone leaves bigger holes.
volume (cu yd) = L × W × (depth ÷ 12) ÷ 27density = gradation × rock typetons = volume × density × 1.1freight = max(75, haul × 5)total = tons × price + freightThe 1.1 covers two separate losses that both come off the top of the layer: angular rip rap carries 30 to 40% void space, and a fresh face settles another 5 to 10% in its first year as the stones shuffle into each other under their own weight. Voids are already inside the bulk densities below, which is why the multiplier is 1.1 and not 1.4. For smaller decorative stone, use the stone calculator instead, and for a drainage trench the french drain calculator.
Not included: geotextile, excavation, machine hire, a toe key, permits, or labour. Bank stabilisation near water is engineered work, and a design velocity belongs to a licensed civil engineer, not to a coverage estimate.
2 to 4 in
1.40 tons/yd³
1.40 tons/yd³
5.70 tons
3 to 6 in
your stone1.30 tons/yd³
1.30 tons/yd³
5.30 tons
6 to 10 in
1.20 tons/yd³
1.20 tons/yd³
4.89 tons
12 to 18 in
1.10 tons/yd³
1.10 tons/yd³
4.48 tons
Rock type shifts every row together: basalt runs 25% heavier than sandstone for the same volume. Confirm the figure against your own quarry's ticket before a large order.
Revetment failures
Every one of these is settled before the first stone lands, and none of them is fixable once the face is built and the water is running.
No geotextile under the stone
Without a non-woven filter (6 oz/sq yd minimum) the bank pumps fines up through the voids, the stone sinks into the hollow it made, and the face fails inside 2 to 3 years.
Rounded river rock instead of angular stone
Rounded stone rolls and slides on a slope. Angular quarry stone keys into its neighbours. Ask for rip rap grade or armour stone by name when you order.
A layer thinner than the stone in it
An armour course cannot be contained by a layer shallower than its own largest stone. Those stones sit proud, rock underfoot and under flow, and work loose one at a time. The section at the top of the page tests your depth against your gradation as you type.
Undersized stone for the water velocity
3 to 6 in stone under flow above 5 ft/s will move in the first real storm. Match the stone to the velocity you actually get, or size up one gradation.
A steep face with no toe protection
Anything steeper than 2:1 needs a key trench, a toe course and often geogrid. Skip them and the stone walks to the bottom over one or two storm seasons and leaves bare soil at the top.
Working in a waterway without the permit
Rip rap near water or wetlands without a Section 404 permit can draw fines of $10,000 to $50,000 a day. Call your Army Corps district office before you call the quarry.
Before the permit
Eight answers in the order they tend to arrive, starting with the one the section at the top of the page exists to settle.
Standard is 1.5 to 2x the D50 stone diameter. For residential projects with 6 to 9" stone, plan for 12 to 18" depth.
Yes. Non-woven geotextile (6 oz minimum) prevents soil migration. Without it, rip rap settles unevenly and fails within 3 to 5 years.
Granite is 8 to 15% denser and harder, ideal for high-flow areas. Limestone costs 20 to 30% less and works for most residential projects.
Almost always. Waterway work requires a Section 404 permit from the Army Corps. Budget 3 to 6 months and $200 to $2,000 in fees.
Material runs $25 to $65/ton. Professional installation adds $40 to $80/ton. A 200 sq ft project costs $1,500 to $4,000 installed.
Steeper slopes require engineered designs with 12 to 18" stone, toe protection, and often geogrid reinforcement.
Rip rap is loose stone on slopes. Gabions are wire mesh cages with smaller stone, better for steep slopes above 1.5:1 but 30 to 50% more expensive.
Properly installed with geotextile and correct sizing, 50 to 100 years. Undersized stone is the most common failure mode.
Haul cost
Armour stone is heavy and cheap by the ton, so the truck is a real part of the bill rather than a rounding error. Every figure below comes off the same $5 a mi rule with a $75 floor that the calculator uses.
5 mi
$75
29%
15 mi
your haul$75
29%
30 mi
$150
45%
60 mi
$300
62%
100 mi
$500
73%
The $75 floor means every haul under 15 mi costs the same, so a very local quarry saves nothing on the truck. On your 5.30 tons that floor works out at $14.15 a ton, which is why one bigger load beats two small ones.
Disclaimer
These estimates are for planning purposes only. Actual costs vary by location, material availability, and project complexity. Always get at least 3 local quotes. This calculator does not replace professional advice.