Soil Texture Triangle Calculator

Getting Your Numbers and Reading the Result

• Start with sand, silt and clay percentages from a lab or a jar test.
• Enter each percent in its field; the tool checks the three total near 100.
• Let the printed class come from the twelve-way USDA triangle, not your eye.
• Read the drainage band to judge whether water sits or sheets away.
• Check the plant-available water range before you size an irrigation schedule.
• Use the handling note to decide if beds, tilth or amendments come first.
• Retest at several spots whenever the yard is not uniform.
• Pair the class with a pH and nutrient test for the full fertility picture.
• Treat any dash as a missing percentage rather than a verdict.

How the Texture Triangle Math Works

Worked Example: From Jar Test to Verdict

• Suppose a jar test reads 40 percent sand, 40 percent silt, 20 percent clay.
• The three total 100, so the data-check band reports the mix looks right.
• Clay at 20 sits below the clay-loam floor, so no clayey class triggers.
• Sand at 40 fails the sandy-loam line and silt at 40 fails the silt-loam test.
• The ordered rules settle on class code 4, which the band prints as Loam.
• The drainage band reads moderate and available water reads 1.4 to 2.0 inches per foot.
• The handling note confirms the benchmark all-around garden soil worth protecting.
• Now change to sand 20, silt 35, clay 45 and the same engine returns Clay.
• That second verdict flips drainage to very slow and points you to raised beds.

The Twelve Classes at a Glance

Key Terms

Texture class

One of twelve USDA categories defined purely by the proportions of sand, silt and clay.

Sand fraction

The coarse particles between 0.05 and 2 millimeters that drive drainage and aeration.

Silt fraction

Mid-size particles that feel floury and hold far more water than sand does.

Clay fraction

The finest plate-like particles that swell, bind water and nutrients, and drain slowly.

Jar test

A home sedimentation method that separates the three fractions so you can estimate percentages.

Texture-by-feel

The field ribbon and gritty test extension agents use to confirm a lab class.

Field Notes from Soil Scientists

• Two soils with the same label can behave opposite, because structure and organic matter let a clay drain well in one field and waterlog in another, so treat the class as a starting point rather than a sentence.
• The triangle is mineral only: it never counts the compost you add, yet organic matter is what most garden amendments actually change, moving workability long after the texture number stays fixed.
• Silt is the quiet trap, because a silt loam feels like loam, drains like loam, then crusts and compacts far harder when wet, which is why floodplain gardens need the gentlest boot traffic.
• Clay percentage is the lever agronomists watch, since even a five-point jump in clay shifts the water-holding and tillage verdict more than any equal move in sand.
• Ask for the class and the calcium carbonate and salt readings together from the lab, because texture alone explains drainage but never explains why a supposedly good soil still stunts a crop.

Common Mistakes and Fixes

• Assuming a bag sold as loam matches the USDA class; run the jar test and let the numbers name it.
• Entering only two percentages and guessing the third instead of making all three total near 100.
• Judging a wet, compacted clay as a permanent verdict when drainage improves once it dries and is amended.
• Chasing a sandy soil with clay imports instead of repeated organic matter that actually holds water there.
• Reading a single spot for a whole bed when texture varies across the yard and retesting is cheap.
• Forgetting a borderline sample belongs to two classes and skimming the guidance for both neighbors.

When to Use This and When Not To

Soil Texture Triangle Calculator: Frequently Asked Questions