Soil Texture Triangle Calculator

Calculator inputs

Use percentage mode for direct soil fractions or gram mode for laboratory mass data.

Sample name

Project reference

Sampling depth (cm)

Input basis

Sand

Silt

Clay

Decimal precision

Auto-normalize when total is not 100

Notes

Example data table

Use these sample combinations to verify classification behavior and compare field or lab results.

Sample	Sand (%)	Silt (%)	Clay (%)	Texture Class
Riverbank Fill	72	18	10	Loamy Sand
Topsoil Blend	40	40	20	Loam
Stormwater Berm	55	15	30	Sandy Clay Loam
Pond Liner Borrow	22	18	60	Clay

Formula used

Normalization formula

Normalized fraction = (component ÷ total entered) × 100

Triangle check

Sand % + Silt % + Clay % = 100%

Classification logic

The normalized point is matched against USDA texture triangle boundary rules.

The calculator first validates or normalizes the three fractions, then assigns the sample to the corresponding texture region. In construction screening, the texture class helps estimate drainage tendency, compaction behavior, cohesion, shrink-swell risk, and expected field handling.

How to use this calculator

Enter a sample name, optional project reference, and depth if available.
Select percentage mode for direct fractions or gram mode for laboratory masses.
Input sand, silt, and clay values from sieve or hydrometer results.
Enable auto-normalization if your percentage total is slightly above or below 100.
Click Calculate Soil Texture to display the result above the form.
Review the ternary plot, behavior summary, and construction note.
Export the output using CSV or PDF for reports, logs, or QA records.

Frequently asked questions

1. What does the soil texture triangle show?

It shows how sand, silt, and clay percentages combine to define a named texture class. Each point inside the triangle belongs to one class, such as loam, clay loam, or sandy clay.

2. Why must the inputs total 100?

The triangle is based on proportional composition. Because the three fractions represent the full fine-earth sample, their percentages must sum to 100. The calculator can normalize small differences automatically.

3. Can I enter gram values instead of percentages?

Yes. Choose gram mode and enter the measured mass of sand, silt, and clay. The calculator converts those values to percentages before classifying the point on the triangle.

4. Does texture alone determine engineering performance?

No. Texture is helpful, but compaction, plasticity, organic content, density, structure, moisture, and mineralogy also affect performance. Use the result as a screening tool, not the only design criterion.

5. Why can two soils behave differently within one texture class?

Texture class groups soils by particle-size proportions, not by structure or mineral type. Two clay loams may share percentages but differ in plasticity, drainage, shrink-swell, and field workability.

6. What is normalization doing here?

Normalization rescales the three inputs so their sum becomes 100. This helps when rounded lab values total 99.8 or 100.3, or when gram inputs need conversion into percentages.

7. Is the graph useful for reporting?

Yes. The ternary graph visually confirms where the sample falls relative to the full texture space. It is useful in field notes, design reviews, and quality-control summaries.

8. Can I use this for agricultural and construction work?

Yes. The texture triangle is widely used across both fields. Construction teams often use it for quick material screening, while agronomy teams use it for drainage and rooting interpretations.