Soil Texture Calculator

USDA texture class from sand, silt, and clay percents.

What it does

Soil texture names the mineral mix: sand from 0.05 to 2 mm, silt from 0.002 to 0.05, clay under 0.002. Twelve USDA classes tile every combination, from open sands through balanced loams to tight clays.

The tool above takes the three percents and returns class with group and drainage beside it. The default 40 sand, 40 silt, 20 clay reads Loam, medium-textured, with moderate drainage and holding.

Classes match extension triangle references: 30 clay with 50 sand and 20 silt is sandy clay loam, 25/65/10 sand/silt/clay is silt loam, and 40/40/20 is loam. Clay punches past its share, with just 20% reading clayey in behavior.

Texture sets water fate: sands drain fast and leach, loams balance, clays hold and seal. Feel tests and jar settling estimate the percents; lab analysis settles disputes.

How to use

1. Type sand, silt, and clay percents.
2. Force the three to add to 100.
3. Read class first, group beside it.
4. Read drainage for watering plans.
5. Jar test when lab numbers miss.
6. Amend structure, never texture.

Formula

sand

0.05 to 2 mm grains, gritty.

silt

0.002 to 0.05 mm, smooth floury.

clay

Under 0.002 mm, sticky, outsized pull.

Triangle boundaries resolve by ordered key, so edge values land deterministically. Groups bundle the 12 classes into coarse, medium, and fine.

Worked example

Reference table

Limits

• Texture only; structure separate.
• Lab beats feel and jar estimates.
• Rock fragments excluded from shares.
• Organic matter ignored in class.

Common mistakes

• Shares adding to 90 or 110.
• Reading silt as clay by smoothness.
• Treating 20% clay as light soil.
• Amending texture instead of structure.
• Watering clay on sand schedules.

Try it yourself

Quick checks. Answers sit tucked under each question.

Questions

Sources

• Colorado State Extension: Estimating Soil Texture
• Maryland Extension: Soil Basics

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