Soil Test Calculator

The numbers off your soil test. Anything the test didn't give, leave as it is.

What the lab measured. Every field here is a reading off your soil report. The numbers you are aiming for go in Nutrient Targets, below.

Mostly soil, in a bed or the ground: leave this off. Mostly potting mix, in pots: tick it to take your numbers to the Soilless Mix Calculator.

Core drag a slider or type the lab value

Nitrogen ppm, 0 if the test didn't give it

Nitrogen available N in ppm (leave 0 if not reported). N moves through soil within weeks, so this counts as a one-time credit, not a level to build up.

Test methods printed on your report, often next to each nutrient. Labs often use a different test for each group, and each gives a different number for the same soil. Find your state's lab.

Phosphorus and potassium ppm

Nutrients what your soil tested at, ppm. Uncheck "Include" for anything that wasn't on your lab report. It grays out here and in Nutrient Targets, and is left out of the reading and plan. While it's checked, a 0 counts as a real reading.

Base saturation % of CEC, leave 0 if not reported

Soil and plants

Salinity & texture leave 0 if not reported. For high sodium, add gypsum before you flush, or the soil can seal up.

Container Mix

This page is for soil in the ground. For a potting mix, use the Soilless Mix Calculator.

The button copies these numbers there, to the mix with the same name as your Sample. A regular soil test only tells you a potting mix's pH. To check its nutrients too, ask your lab for a greenhouse media test (SME). While this is checked, the plan, share link and PDF are off, since they're sized for soil in the ground.

Where the soil should end up. Nothing here comes off your lab report: pick a preset for your crop, then tune any field. Every amendment below is sized off the gap between these numbers and Your Report, above.

Target nutrients where each one should land, ppm. Anything you unchecked under Include in Your Report is grayed out here too.

Applied

👉 Swipe the table sideways to see every column (Target, Status, Notes).

General agronomic ranges. Crop needs vary, so pair this with your lab's interpretation and, for lime, a buffer-pH rec.

Tick the reports to compare. They can come from any sample or any space.

Color shows each value against that test's own target: green at/above, amber high, red below.

Soil pH

How sour (acidic) or chalky (alkaline) the soil is, on a scale where 7 is neutral. Most garden plants and lawns do best around 6 to 7; blueberries and azaleas need 4.5 to 5.5. Too low or too high and the nutrients already in the soil get locked up where roots can't take them.

ppm

Parts per million, the unit a soil test reports nutrients in. It is how much the lab could pull out of a sample, not the total in the ground, so it is only comparable between tests from the same lab.

Nitrogen (ppm)

The nitrate reading on the report, sometimes printed as NO₃-N. Nitrogen washes through soil within weeks, so a test is only a snapshot and nothing here is added to build it up. Under about 10 ppm is low, over 25 is plenty.

Phosphorus (P, ppm)

Feeds roots, flowers and fruit. It barely moves in soil, so what is added stays for years. Most gardens need 35 to 50 ppm; far above that it runs off into water.

Potassium (K, ppm)

Helps plants handle drought, cold and disease. Most gardens and lawns need 150 to 200 ppm.

Soil type

How sandy or clayey the soil is. Clay takes several times more lime or sulfur than sand to shift the same pH. Growers call it texture. A handful that feels gritty and falls apart is sandy; one that is sticky and holds a ribbon is clay.

Plants you're growing

Sets the pH and the nutrient levels to aim for. Vegetables and heavy feeders need more phosphorus and potassium than a lawn does.

Agricultural lime

Ground limestone. Raises pH slowly, over six to twelve months, so it is best worked in during fall. More than about 50 lb per 1,000 sq ft goes on in two passes.

Elemental sulfur

Lowers pH. Soil bacteria turn it into acid over a few months in warm, damp soil, so apply it in split doses and retest.

MAP (11-52-0)

A phosphorus fertilizer. The three numbers on any fertilizer bag are its nitrogen, phosphorus and potassium, in percent (N-P-K). Bone meal is the organic option.

Sulfate of potash (0-0-50)

A potassium fertilizer with no nitrogen or phosphorus. Muriate of potash (0-0-60) is cheaper but adds chloride, which some plants dislike.

Bed or plot, Lawn, Field

What the amounts are measured for. A bed gives the exact weight for its size and depth; lawn is per 1,000 sq ft; field is per acre. For potting mix, tick "Is this a container mix?" instead.