Calculator
Example Data Table
| Amount | Type | Tank | Active % | PPM (Product) | PPM (Active) |
|---|---|---|---|---|---|
| 1.00 oz | Weight | 1.00 gal | 100% | 7,489.15 | 7,489.15 |
| 0.50 oz | Weight | 2.00 gal | 80% | 1,872.29 | 1,497.83 |
| 2.00 fl oz | Fluid (ρ=1.00) | 10.00 L | 50% | 5,914.71 | 2,957.35 |
Formula Used
PPM in water-based mixes is commonly treated as mg/L.
- Liters = gallons × 3.785411784
- Product mg (weight oz) = ounces × 28,349.523125
- Product mg (fluid oz) = fl oz × 29.5735295625 × density(g/mL) × 1000
- Active mg = product mg × (active % ÷ 100)
- PPM (product) = product mg ÷ liters
- PPM (active) = active mg ÷ liters
How to Use This Calculator
- Enter how many ounces of product you add to your mix.
- Select Weight for powders, or Fluid for liquids.
- If using fluid ounces, set density; water-like liquids use 1.00.
- Enter your tank volume and choose gallons or liters.
- Set the label’s active percentage to estimate active-ppm.
- Press Calculate to see ppm above the form, then export.
Why ppm matters in garden mixing
Parts per million (ppm) is a way to compare strength across tanks, sprayers, and watering cans. In most mixes, ppm is treated as milligrams per liter (mg/L). When you track ppm, you reduce guesswork and keep feeding, spraying, and sanitation routines consistent across batches.
How ounces become mg/L
This calculator converts your added ounces into milligrams, then divides by the solution volume in liters. For weight ounces, it uses 28,349.523 mg per ounce. For fluid ounces, it converts to milliliters, applies density to estimate grams, then converts grams to milligrams. The output is an mg/L value.
Product ppm versus active ppm
Many labels list an active ingredient percentage, while the rest is inert carriers, surfactants, or salts. Product ppm reflects the full material added. Active ppm estimates only the active portion by multiplying by the label percentage. This distinction helps when you compare different formulations or switch brands but want equivalent active strength. It is especially useful for concentrates with similar names but very different percentages.
Choosing weight or fluid inputs correctly
Use weight ounces for powders, granules, or dry salts, because the dose is based on mass. Use fluid ounces for liquids measured in a cup or bottle. If density is unknown, 1.00 g/mL is a reasonable approximation for water-like products, but thicker concentrates can shift results upward or downward. For best repeatability, measure the same way every time and keep your measuring tools dedicated to one product type.
Practical checks for safer, repeatable results
Confirm your tank volume after adding concentrates, especially in small sprayers where the fill line is hard to read. Rinse measuring tools into the tank to avoid under-dosing and reduce residue. If a calculated ppm seems extreme, recheck units, decimal places, and whether the label dose is per gallon or per liter. Keep a simple log of ppm targets for each crop stage and application type, and adjust only one variable at a time when troubleshooting plant response.
FAQs
1) Is ppm the same as mg/L in this calculator?
Yes. For water-based garden mixes, ppm is commonly treated as mg/L. The calculator outputs mg/L and labels it as ppm for practical mixing and comparison.
2) When should I use fluid ounces instead of weight ounces?
Use fluid ounces when the product is measured by volume, such as liquids from a bottle or measuring cup. Use weight ounces for powders or granules measured on a scale.
3) What density should I enter for liquids?
If you do not know density, enter 1.00 g/mL for water-like liquids. If a label or safety sheet lists density, use that value for the most accurate ppm.
4) Why are there two ppm outputs?
“Product ppm” includes everything added. “Active ppm” estimates only the active ingredient based on the percentage you enter. This helps compare different formulations more fairly.
5) Does this work for gallons and liters?
Yes. Enter gallons or liters, and the tool converts gallons to liters internally. Results are always based on liters so ppm stays consistent across units.
6) How can I lower ppm without changing the dose?
Increase the final solution volume by adding more water, or split the dose across multiple tanks. Lowering ppm by dilution is often safer than reducing dose below label guidance.