What are the 12 USDA soil textural classes?

Sand, Loamy Sand, Sandy Loam, Sandy Clay Loam, Sandy Clay, Loam, Clay Loam, Silt Loam, Silt, Silty Clay Loam, Silty Clay, and Clay. Each class has defined ranges of sand, silt, and clay that place it within the texture triangle.

Do the three percentages have to add up to 100?

Yes. Sand + silt + clay must equal exactly 100%. This tool auto-calculates clay from the sand and silt values you enter, ensuring the constraint is always satisfied.

How is particle size defined for each fraction?

USDA definitions: sand = 0.05–2 mm diameter; silt = 0.002–0.05 mm; clay = less than 0.002 mm. These differ slightly from international (ISO/ISSS) standards, so results may vary if your lab used a different classification system.

What does "loam" mean in soil science?

Loam is a balanced mixture of sand, silt, and clay (roughly 25–50% sand, 25–50% silt, 10–25% clay). It is often considered ideal for plant growth because it retains moisture while still draining well.

Can I use this for international (FAO/WRB) soil classification?

This tool implements the USDA texture triangle only, which is the standard used in North America. FAO and WRB systems use slightly different particle-size boundaries, so results may differ from those standards.

Soil Classification Tool

Enter sand, silt, and clay percentages to identify your soil textural class using the USDA texture triangle.

Particle Size Percentages

Sand (%) 0.05 – 2 mm

Silt (%) 0.002 – 0.05 mm

Clay (%) < 0.002 mm — auto-calculated

Total: 0%

Enter sand and silt values, then click Classify.

USDA Soil Textural Classes — Quick Reference

Class	Sand (%)	Silt (%)	Clay (%)
Sand	85–100	0–15	0–10
Loamy Sand	70–90	0–30	0–15
Sandy Loam	43–85	0–50	0–20
Sandy Clay Loam	45–80	0–28	20–35
Sandy Clay	45–65	0–20	35–55
Loam	23–52	28–50	7–27
Clay Loam	20–45	15–55	27–40
Silt Loam	0–50	50–88	0–27
Silt	0–20	80–100	0–12
Silty Clay Loam	0–20	40–73	27–40
Silty Clay	0–20	40–60	40–60
Clay	0–45	0–40	40–100

Summary

This tool classifies soil into one of 12 USDA textural classes (such as clay, loam, sandy loam, or silt loam) based on the percentage of sand, silt, and clay particles in a soil sample. It uses the official USDA Natural Resources Conservation Service texture triangle boundaries. The classification helps agronomists, gardeners, engineers, and environmental scientists understand soil behavior for water retention, drainage, tillage, and structural support.

How it works

Enter the percentage of sand in your soil sample.
Enter the percentage of silt in your soil sample.
The clay percentage fills in automatically so all three sum to 100%.
Click Classify to run the USDA texture triangle algorithm.
The tool displays the textural class name with a brief description of its properties.

Use cases

Determine soil textural class from a lab particle-size analysis report.
Guide irrigation scheduling based on water-holding capacity of the soil type.
Select appropriate plants and crops for a specific soil texture.
Assess construction suitability — clay soils expand and shrink with moisture.
Support environmental remediation planning by understanding soil drainage rates.
Quickly verify field texture estimates against calculated percentages.
Teach soil science concepts using an interactive triangle classifier.
Cross-check USDA Web Soil Survey data against your own sample measurements.

Frequently Asked Questions

Last updated: 2026-05-29 · Reviewed by Nham Vu