Soil texture calculator
Enter the sand and clay percentages from a lab test or a jar test. The silt share is the rest of 100 %. The calculator places the soil on the USDA texture triangle and returns one of its twelve classes.
Runs in your browser: nothing you enter is sent anywhere.
How to use
- Enter the percentage of sand and of clay from your soil test.
- Read the texture class and the silt share.
How it works
The USDA texture triangle divides all sand-silt-clay mixes into twelve classes. The calculator applies the class limits of the USDA Soil Survey Manual, for example:
- sand: silt + 1.5 × clay is below 15;
- loam: clay 7–27 %, silt 28–50 %, sand 52 % or less;
- silt loam: silt 50 % or more with clay 12–27 %, or silt 50–80 % with clay under 12 %;
- clay: clay 40 % or more, sand 45 % or less, silt under 40 %.
The other classes fill the remaining parts of the triangle, so every mix falls into exactly one.
Example
A test shows 40 % sand and 20 % clay:
- silt = 100 − 40 − 20 = 40 %;
- clay is between 7 and 27 %, silt between 28 and 50 %, sand not over 52 %;
- so the soil is a loam.
With 65 % sand and 10 % clay (25 % silt) the result is a sandy loam; with 10 % sand and 30 % clay it is a silty clay loam.
Tips and common mistakes
- Use the percentages of the fine earth (under 2 mm). If your report lists gravel, leave it out and rescale.
- Organic matter is removed before a lab measures texture; compost changes how the soil behaves, not its texture class.
- Texture changes with depth. Test topsoil and subsoil separately if drainage matters.
Frequently asked questions
What is soil texture?
The proportions of sand, silt and clay particles in the mineral part of the soil. In the USDA system sand is 2 to 0.05 mm, silt 0.05 to 0.002 mm and clay smaller than 0.002 mm. Gravel and organic matter are left out of the percentages.
Why do I only enter sand and clay?
The three shares add up to 100 %, so two of them fix the third. The calculator works out silt as 100 − sand − clay, which avoids a sum that does not quite reach 100.
How do I measure it at home?
A jar test gives a rough figure: shake soil with water and a little dish soap, then mark the layers as they settle — sand within a minute or so, silt over a few hours, clay over a day or more. A soil lab gives exact numbers.
What is the best texture for a garden?
Loam — a balanced mix — holds water and nutrients and still drains, so it suits most plants. Sandy soils drain fast and need more watering and feeding; clay soils hold water and nutrients but drain slowly and compact. Compost improves both.