Mass / Mass (e.g., mg/kg)
Mass / Volume (e.g., mg/L)
Parts Per Million (PPM)
Understanding Parts Per Million (PPM)
In chemistry, environmental science, and water quality testing, PPM (Parts Per Million) is a measurement used to express the concentration of a very dilute substance in a solution. One PPM is equivalent to one milligram of something per liter of water (mg/L) or one milligram of something per kilogram of soil (mg/kg).
How the PPM Formula Works
The core concept of PPM is a ratio. To find the concentration in parts per million, you divide the mass of the solute by the total mass (or volume) of the solution and then multiply by one million.
PPM Formula: PPM = (Mass of Solute / Total Mass of Solution) × 1,000,000
Practical Calculation Examples
To help you understand how to use the calculator, here are two common scenarios:
Example 1: Water Quality. If you find 0.05 grams of lead in 1,000 liters of water, what is the PPM?
Calculation: (50mg / 1000L) = 0.05 PPM.
Example 2: Mixing Fertilizers. You mix 2 grams of nutrients into 50,000 grams (50kg) of soil.
Calculation: (2g / 50,000g) × 1,000,000 = 40 PPM.
PPM vs. PPB vs. Percentage
It is helpful to visualize how PPM relates to other common units of measurement:
Unit
Equivalent Ratio
Percentage
10,000 PPM
1 / 100
1%
1,000 PPM
1 / 1,000
0.1%
1 PPM
1 / 1,000,000
0.0001%
1 PPB
1 / 1,000,000,000
0.0000001%
Frequently Asked Questions
Is mg/L the same as PPM?
Yes, in water-based solutions, 1 milligram per Liter (mg/L) is exactly equal to 1 PPM because 1 liter of water weighs approximately 1 kilogram (1,000,000 milligrams).
Why is PPM used instead of Percentage?
Percentages are difficult to read for very small concentrations. For example, 5 PPM is 0.0005%. Scientists use PPM to keep numbers manageable and precise when dealing with trace elements.
function updateLabels() {
var mode = document.getElementById('calcMode').value;
var soluteLabel = document.getElementById('soluteLabel');
var solutionLabel = document.getElementById('solutionLabel');
if (mode === 'massMass') {
soluteLabel.innerHTML = 'Solute Mass (mg)';
solutionLabel.innerHTML = 'Total Solution Mass (kg)';
} else {
soluteLabel.innerHTML = 'Solute Mass (mg)';
solutionLabel.innerHTML = 'Total Solution Volume (L)';
}
}
function calculatePPM() {
var solute = parseFloat(document.getElementById('soluteVal').value);
var solution = parseFloat(document.getElementById('solutionVal').value);
var mode = document.getElementById('calcMode').value;
var resultDiv = document.getElementById('ppmResult');
var resultVal = document.getElementById('resultVal');
var altResults = document.getElementById('altResults');
if (isNaN(solute) || isNaN(solution) || solution <= 0) {
alert('Please enter valid positive numbers for both fields.');
return;
}
// Since 1 mg/kg = 1 PPM and 1 mg/L = 1 PPM
// Formula: mg / units
var ppm = solute / solution;
var ppb = ppm * 1000;
var percent = ppm / 10000;
resultVal.innerHTML = ppm.toLocaleString(undefined, {minimumFractionDigits: 0, maximumFractionDigits: 4}) + ' PPM';
altResults.innerHTML = 'Equivalent to:' +
ppb.toLocaleString(undefined, {minimumFractionDigits: 0, maximumFractionDigits: 2}) + ' PPB (Parts Per Billion)' +
percent.toLocaleString(undefined, {minimumFractionDigits: 0, maximumFractionDigits: 8}) + '% (Percentage)';
resultDiv.style.display = 'block';
}
function resetPPM() {
document.getElementById('soluteVal').value = ";
document.getElementById('solutionVal').value = ";
document.getElementById('ppmResult').style.display = 'none';
}