Determine USDA soil texture class from sand, silt, and clay percentages. Enter particle size analysis results to classify your soil.
The Soil Texture Triangle Calculator determines the USDA soil texture class from the percentages of sand, silt, and clay in your soil. Soil texture is one of the most fundamental properties affecting water-holding capacity, drainage, nutrient retention, workability, and compaction resistance.
The USDA texture triangle divides soils into 12 classes based on particle size distribution: sand, loamy sand, sandy loam, loam, silt loam, silt, sandy clay loam, clay loam, silty clay loam, sandy clay, silty clay, and clay. Each class has distinct management implications for irrigation scheduling, fertilizer application, and tillage practices.
This calculator uses the standard USDA classification system based on percent sand (0.05–2.0 mm), silt (0.002–0.05 mm), and clay (<0.002 mm). Enter values from a laboratory particle size analysis or estimate from the feel method. Whether you are a beginner or experienced professional, this free online tool provides instant, reliable results without manual computation. By automating the calculation, you save time and reduce the risk of costly errors in your planning and decision-making process.
Knowing your soil’s texture class is essential for irrigation scheduling, drainage design, fertilizer management, and engineering applications. Many recommendation tables are indexed by texture class, making this determination a prerequisite for other calculators. Having a precise figure at your fingertips empowers better planning and more confident decisions. Manual calculations are error-prone and time-consuming; this tool delivers verified results in seconds so you can focus on strategy.
The USDA texture classification is defined by boundary lines on the texture triangle: Clay: ≥40% clay Silty clay: ≥40% clay AND ≥40% silt Sandy clay: ≥35% clay AND ≥45% sand Clay loam: 27–40% clay AND ≤20–45% sand Silty clay loam: 27–40% clay AND <20% sand Sandy clay loam: 20–35% clay AND >45% sand Loam: 7–27% clay, 28–50% silt, ≤52% sand Silt loam: ≤50% silt AND 12–27% clay, OR 50–80% silt AND <12% clay Silt: ≥80% silt AND <12% clay Sandy loam: <20% clay, <50% silt, 43–80% sand Loamy sand: <15% clay, <50% silt, 70–90% sand Sand: <10% clay, <15% silt, ≥85% sand
Result: Loam
With 40% sand, 40% silt, and 20% clay, the soil falls in the Loam class. Loam is considered an ideal agricultural soil with balanced drainage, water-holding capacity, and nutrient retention.
From coarsest to finest: Sand, Loamy Sand, Sandy Loam, Loam, Silt Loam, Silt, Sandy Clay Loam, Clay Loam, Silty Clay Loam, Sandy Clay, Silty Clay, and Clay. Each has distinct physical properties. Sand drains quickly but holds little water. Clay holds water and nutrients but can be difficult to work. Loams offer the best balance for general agriculture.
Moisten a ball of soil and squeeze it between thumb and forefinger to form a ribbon. Sand: no ribbon. Sandy loam: weak ribbon <1 inch. Loam: ribbon 1–2 inches. Clay loam: ribbon 2–3 inches. Clay: strong ribbon >3 inches. Add the feel (gritty = sand, smooth = silt, sticky = clay) for finer distinction.
Soil texture affects foundation design, septic system suitability, road construction, and drainage engineering. Clay soils shrink and swell with moisture changes, causing structural damage. Sandy soils have high bearing capacity but may require stabilization. Percolation tests for septic systems are directly related to texture.
Loam, silt loam, and clay loam are generally the most productive because they balance drainage and water retention. However, any texture can be productive with proper management. Sandy soils need frequent irrigation; clay soils need careful tillage timing.
Practically, no. Adding enough sand to change a clay soil’s texture requires enormous volumes (hundreds of tons per acre). You can improve soil structure through organic matter, gypsum, and reduced tillage, which makes any texture perform better.
Texture is the proportion of sand, silt, and clay particles — it’s permanent. Structure is how those particles are arranged into aggregates — it can be improved or degraded by management. Good structure makes any texture work better.
Sandy soils: high infiltration rate, low water-holding capacity — irrigate frequently with small amounts. Clay soils: low infiltration rate, high water-holding capacity — irrigate less often with more water. Loamy soils fall in between.
Gravel and coarse fragments larger than 2mm are excluded from the texture analysis. If your soil has gravel, the sand + silt + clay percentages of the fine earth fraction should still sum to 100%.
Clay particles have much higher surface area and charge than sand or silt. Sandy soils typically have CEC of 2–8 meq/100g, while clay soils range from 20–50 meq/100g. Organic matter contributes CEC independent of texture.