Soil Texture Triangle Calculator

The USDA soil texture triangle turns three numbers (percent sand, silt and clay) into one of 12 texture classes, and that class predicts how a soil drains, holds water and handles. Enter your numbers, or plot the soil USDA mapped at your address.

Sandy clay loam

Enter your percentages

Type any two and the third is filled in.

Sand %

Silt %

Clay %

Your USDA texture class

sandy clay loam

50% sand · 20% silt · 30% clay

20–35% clay, over 45% sand.

With 20% clay or more, these soils behave as sticky, gummy clayey soils.

At 30% clay, expect clay-like behavior: Colorado State University Extension notes that a soil with as little as 20% clay can behave like a clay soil.

Percentages are shares of the mineral particles smaller than 2 mm. Classes use the USDA Soil Survey Manual boundaries. How we calculate this.

Use my soil

Plot the soil USDA mapped at an address, layer by layer.

US addresses only: street address, city and state, or ZIP.

Where US topsoil acres fall on the texture triangle. Source: USDA NRCS soil survey (SSURGO).

The soil texture triangle is the USDA chart that names a soil from its sand, silt and clay percentages. Each side carries one particle size, and the point where your three percentages meet falls inside one of 12 texture classes, from sand to clay^[1]. The class predicts drainage, water holding and workability^[2].

Sand, silt and clay: the three particle sizes

Texture is about particle size only. USDA sorts the mineral grains smaller than 2 mm into three groups, and the triangle shows how much of each your soil contains^[1].

Particle	Diameter	How it feels
Sand	0.05–2.0 mm	Gritty
Silt	0.002–0.05 mm	Smooth, like flour
Clay	Under 0.002 mm	Sticky

The sizes are the Soil Survey Manual’s^[1]; how each one feels is Colorado State University Extension’s description^[3]. USDA also splits sand into five sizes, from very fine (0.05–0.10 mm) to very coarse (1.0–2.0 mm)^[1]. Texture is about single grains, not the crumbs they stick together in; for those aggregates and a closer look at the three particles, see sand, silt and clay.

1,000×: the largest sand grain (2 mm) is a thousand times wider than the largest clay particle (0.002 mm), calculated from USDA’s size limits^[1].

How to read the soil triangle: a worked example

Take a soil with 50% sand, 20% silt and 30% clay, the example Colorado State University Extension uses^[3].

Find 30 on the clay edge (the left side) and follow that line straight across.
Find 50 on the sand edge (the bottom) and follow its line up and to the left, parallel to the right side.
The two lines cross inside sandy clay loam. The 20% silt line runs through the same point, because the three shares always add up to 100.

Load this example into the calculator

New to the chart? See how to read it step by step, or print a worksheet with an answer key.

Every point inside a region gets that region’s name. So soils with quite different numbers can share a class, and two soils a point apart can land on either side of a line.

The 12 USDA texture classes

These are the class definitions from the USDA Soil Survey Manual^[1], with what each class usually means in a garden^[4][2][3]. Each class name links to its own page.

Class	USDA definition	How it behaves
sand	Mostly sand: over 85%.	Sandy soils drain quickly and don't hold water and nutrients well, so they dry out fast.
loamy sand	70–90% sand.	Sandy soils drain quickly and don't hold water and nutrients well, so they dry out fast.
sandy loam	Mostly sand, with under 20% clay.	Sandy soils drain quickly and don't hold water and nutrients well, so they dry out fast.
loam	A balanced mix: 7–27% clay, 28–50% silt, no more than 52% sand.	Loam holds enough water for plants but drains well enough for roots to breathe.
silt loam	At least 50% silt, under 27% clay.	Silty soils feel smooth and hold water better than sandy soils, because their pores are smaller.
silt	At least 80% silt, under 12% clay.	Silty soils feel smooth and hold water better than sandy soils, because their pores are smaller.
sandy clay loam	20–35% clay, over 45% sand.	With 20% clay or more, these soils behave as sticky, gummy clayey soils.
clay loam	27–40% clay, 20–45% sand.	With 20% clay or more, these soils behave as sticky, gummy clayey soils.
silty clay loam	27–40% clay, no more than 20% sand.	With 20% clay or more, these soils behave as sticky, gummy clayey soils.
sandy clay	35% or more clay, over 45% sand.	Clay soils hold a lot of water and nutrients but drain slowly, can be short of air, and get very hard when dry.
silty clay	At least 40% clay and 40% silt.	Clay soils hold a lot of water and nutrients but drain slowly, can be short of air, and get very hard when dry.
clay	At least 40% clay, under 40% silt.	Clay soils hold a lot of water and nutrients but drain slowly, can be short of air, and get very hard when dry.

What your texture class tells you

Sandy classes (sand, loamy sand and sandy loam) drain quickly and don’t hold water or nutrients well, so they dry out fast^[4].
Loam holds enough water for plants but drains well enough for roots to breathe. That’s the balance gardeners mean by “nice loam”^[2].
Silty soils feel smooth and hold water better than sand, because their pores are smaller^[4].
Clay holds water and nutrients but drains slowly, can be short of air, and gets very hard when dry^[4]. Clay takes over early: a soil with only 20% clay behaves as a sticky, gummy clayey soil^[3].
Texture isn’t the whole story. Soils rich in organic matter have more stable pores that let water soak in^[5], which is why our address lookup reports drainage, water storage and USDA’s own ratings alongside the class.

Where to get your percentages

A soil lab: a particle-size test reports the sand, silt and clay and the USDA class^[6].
The jar test: an at-home estimate; the clay can take 1 to 3 days to settle^[3].
The ribbon test: a by-feel estimate that needs no jar.
Your address: USDA has already recorded sand, silt and clay for the layers of mapped soils^[7]. Enter an address above to plot it, every layer from the topsoil down.

Ways people use the soil triangle

Reading a lab report. A lab’s particle-size test reports the three percentages and the USDA class^[6]; the triangle shows where that class sits.
Checking a jar test. Measure your layers in the jar test calculator and see where they land.
Comparing your yard with USDA’s map. Plot the mapped soil for your address, then your own measurement, and see whether your garden matches the surrounding soil.
Teaching and homework. Enter any set of percentages to check an answer.

How we calculate this

We classify with the USDA Soil Survey Manual texture-class definitions, written out as rules in our code^[1]. The colored regions on the triangle are drawn from those same rules, and our tests check that every point on a 1% grid gets the class of the region it sits in.
Inputs are shares of the fine earth (mineral particles under 2 mm) and the three must total 100^[1]. We round to one decimal.
Address results use the representative sand, silt and clay values USDA records for each soil layer. They describe the typical soil of the mapped area, not a sample from your lot^[7]. See our methodology.

NRCS publishes its own Soil Texture Calculator, Excel workbooks that class a sample from the same three percentages^[8], and Colorado State’s jar test sends readers to it or to the triangle^[3].

The exact USDA rules we use

Evaluated in order; sand = % sand, silt = % silt, clay = % clay^[1].

sand: silt + 1.5 × clay < 15
loamy sand: 15 ≤ silt + 1.5 × clay and silt + 2 × clay < 30
sandy loam: (7 ≤ clay < 20 and sand > 52 and silt + 2 × clay ≥ 30) or (clay < 7 and silt < 50 and silt + 2 × clay ≥ 30)
loam: 7 ≤ clay < 27 and 28 ≤ silt < 50 and sand ≤ 52
silt loam: (silt ≥ 50 and 12 ≤ clay < 27) or (50 ≤ silt < 80 and clay < 12)
silt: silt ≥ 80 and clay < 12
sandy clay loam: 20 ≤ clay < 35 and silt < 28 and sand > 45
clay loam: 27 ≤ clay < 40 and 20 < sand ≤ 45
silty clay loam: 27 ≤ clay < 40 and sand ≤ 20
sandy clay: clay ≥ 35 and sand > 45
silty clay: clay ≥ 40 and silt ≥ 40
clay: clay ≥ 40 and silt < 40 and sand ≤ 45

Frequently asked questions

What is the soil texture triangle?

A chart USDA uses to name soils by particle size. Its three sides measure percent sand, silt and clay, and its 12 regions are the texture classes^[1].

Is this the USDA soil texture triangle?

Yes. It uses the class definitions in USDA’s Soil Survey Manual^[1]. NRCS also publishes its own texture calculator for the same three percentages^[8].

Do the percentages have to add up to 100?

Yes. Texture describes only the mineral particles smaller than 2 mm (sand, silt and clay), so their shares always total 100%^[1]. Gravel and organic matter aren’t part of it.

Is a soil triangle chart or soil texture pyramid the same thing?

Yes. People call it a triangle, a chart or a pyramid; it's the same three-sided diagram.

Is soil texture the same as soil type?

Not quite. Texture is one property: the mix of sand, silt and clay. USDA’s maps name soils by series, and each series description lists the soil properties that define it^[9]. Look up the soil at your address.

Where do I get my percentages?

From a soil lab's particle-size test, or estimate them yourself with a jar test.

What if I don't have numbers at all?

Try the ribbon test, which estimates your class by feel.

Sources

Marko Visic · MPharm, BSc Physics · Last reviewed November 13, 2026

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