Dilution Calculator

Safe handling when mixing concentrates

A few handling rules that apply regardless of what you are diluting:

• Follow the product's mixing order. There is no universal fill order for every pesticide, fertilizer, cleaner, or formulation. Many spray labels start with some water in the tank and then specify when to add each product under agitation; the product label controls.
• Wear chemical-resistant gloves. Even products that are safe when diluted can cause skin irritation at concentrate strength. Use nitrile or chemical-resistant gloves↗ whenever handling undiluted product.
• Measure accurately — do not eyeball. A measuring error at a 1:32 ratio that is off by even 25% means significantly wrong concentration. Use a measuring syringe↗ for amounts under 2 fl oz and a graduated cylinder↗ for larger volumes.
• Do not assume a diluted mix can be stored. Some products require prompt use after mixing. Follow the label for storage and disposal, and never put chemicals in food or drink containers.
• Check the label first. Some products have specific dilution restrictions — minimum or maximum concentrations, approved use sites, or container material requirements. Always read the full label before mixing. Our label dilution guide explains how to read mixing instructions correctly.

How dilution works: ratios, percentages, and parts

A dilution is the process of reducing the concentration of a substance by mixing it with a solvent — almost always water. The result is a solution where the concentrate is spread through a larger total volume. Dilution is used in pesticide application, cleaning products, fertilizers, and hundreds of other liquid chemical applications.

The 1:X ratio format

When a label says 1:32, it means: for every 1 part of concentrate, add 32 parts of water. The total final volume is 1 + 32 = 33 parts. So in a 1-gallon container (128 fl oz), you would add 128 ÷ 33 = 3.88 fl oz of concentrate and fill the rest with water.

Concentrate = Total volume ÷ (1 + X)

This is the core formula behind the Ratio tab. The X value is the number after the colon — the bigger the X, the weaker the solution.

The percentage format

A 2% solution means 2 parts concentrate per 100 parts final solution (not per 100 parts water). To make 1 gallon of a 2% solution: 128 fl oz × 0.02 = 2.56 fl oz of concentrate.

Concentrate = Total volume × (Percentage ÷ 100)

Use the Percentage tab when your label states a target concentration directly as a percentage. The equivalent ratio is 1:(100/% − 1) — so 2% = approximately 1:49.

Ratio vs percentage: quick conversion

Worked examples

These three examples walk through the exact calculation for the most common dilution scenarios. Each mirrors one tab in the calculator above — use them to double-check your result makes sense.

Example 1 — Ratio: herbicide at 1:32 in a 2-gallon backpack sprayer

A herbicide label says "mix at 1:32 (concentrate:water)." You have a 2-gallon backpack sprayer.

Total volume = 2 gal = 256 fl oz.
Concentrate = 256 ÷ (1 + 32) = 256 ÷ 33 = 7.76 fl oz.
Water = 256 − 7.76 = 248.2 fl oz (≈ 1.94 gal).

In practice: add roughly 7¾ fl oz (about 15½ tablespoons) of concentrate to the tank, then fill to the 2-gallon mark with water. The calculator gives this result instantly in the Ratio tab — enter ratio 32 and volume 2 gallons.

Example 2 — Percentage: disinfectant at 2% solution in a 32 fl oz spray bottle

A cleaning concentrate label says "dilute to a 2% solution for general surface disinfection." You want to fill a 32 fl oz trigger spray bottle.

Concentrate = 32 × (2 ÷ 100) = 32 × 0.02 = 0.64 fl oz (≈ 19 mL, ≈ 1.3 tbsp).
Water = 32 − 0.64 = 31.36 fl oz.

The equivalent ratio is 1:49 (roughly 1:50). Add just under two tablespoons of concentrate and fill the rest of the bottle with water. Use the Percentage tab — enter 2% and 32 fl oz.

Example 3 — Hose-End: lawn fertilizer at 1.5 fl oz/gal through a 16:1 hose-end sprayer

A liquid lawn fertilizer label says "apply at 1.5 fl oz per gallon." Your hose-end sprayer has a 32 fl oz jar and a fixed 16:1 siphon ratio.

Jar size = 32 fl oz = 0.25 gal.
Concentrate in jar = 1.5 × 0.25 × (16 + 1) = 1.5 × 0.25 × 17 = 6.375 fl oz (≈ 189 mL).
Fill the remaining 25.6 fl oz of the jar with water.
One full jar produces 32 × 17 = 544 fl oz = 4.25 gallons of finished spray.

Use the Hose-End tab — enter siphon ratio 16, jar size 32 fl oz, label rate 1.5 fl oz/gal.

Hose-end sprayer dilution: how it works

Hose-end sprayers are not all calibrated the same way. Some models draw jar liquid at a stated fixed water:jar ratio; others use a dial marked directly in teaspoons, tablespoons, or ounces of product per gallon of water. Use the method documented for your exact sprayer rather than converting a dial setting into an assumed siphon ratio.

Why hose-end dilution is different from tank mixing

With a standard sprayer tank, you prepare the spray mix in the tank. With a hose-end sprayer, the spray head meters liquid from the jar into hose water during application. Depending on the model, the jar may hold concentrate or a pre-diluted jar mixture. This means:

• For a fixed-ratio unit, both the verified draw ratio and the product's label rate are needed.
• For a dial-rate unit, use the manufacturer's dial setting that matches the product label.
• Do not infer an application rate from jar size or walking speed alone; follow the label's area/rate directions.

The hose-end dilution formula

For a fixed-ratio unit, the key question is: what concentration must the jar mixture have so the finished spray matches the label rate?

Concentrate in jar (fl oz) = Label rate (fl oz/gal) × (Jar size in gallons) × (Siphon ratio + 1)

Example: Label rate 1.5 fl oz/gal, 32 fl oz jar (0.25 gal), 16:1 siphon ratio:
1.5 × 0.25 × (16 + 1) = 1.5 × 0.25 × 17 = 6.375 fl oz in the jar.

The Hose-End tab applies this only when the water:jar draw ratio is known. Enter the verified ratio, jar size, and label rate; the result shows the amount of concentrate in the jar mixture and the theoretical finished-spray volume if the full jar is drawn at that fixed ratio.

Fixed-ratio vs dial-rate hose-end sprayers

Ortho states that Dial N Spray has 14 dial settings and instructs users to set the dial according to the concentrate product label. Other brands and models can use different metering systems.

How to make a dilution: step-by-step

The calculator gives you the arithmetic. The product label gives you the required PPE, mixing sequence, compatibility limits, use sites, and application directions. Use this checklist only as a measurement workflow; when it conflicts with the label, the label controls.

1. Read the label first. Confirm the dilution ratio, any mixing restrictions, required PPE, and whether the product has a minimum or maximum concentration requirement. Some products must not be diluted below a certain strength or they become ineffective.
2. Put on your PPE before opening the concentrate. Chemical-resistant gloves↗ at minimum. Eye protection if required by the label.
3. Follow the label's initial fill instruction. Many spray products direct you to begin with part of the required water and agitation, but formulations differ. Use the sequence printed on the product label.
4. Measure concentrate precisely. Use a measuring syringe↗ for amounts under 2 fl oz (60 mL) and a graduated cylinder↗ for larger amounts. Never estimate by pouring directly from the concentrate container into the spray tank — this is the single most common cause of over-concentration.
5. Add products in the label-specified order and use agitation when required. Multi-product tank mixes can have a different sequence from a single-product dilution.
6. Top off to the final volume with the remaining water. Do not add more concentrate. The final volume determines the concentration — if you end up with less liquid than planned, your solution is stronger than intended.
7. Agitate before spraying and periodically during application to keep the solution uniform. Some concentrates can settle or separate, particularly suspension concentrates (SC formulations).

Pro tip: If you are mixing multiple products in one tank, the fill order matters beyond just water-first. See the WALES Mixing Order Guide for the correct sequence when combining herbicides, insecticides, fungicides, and adjuvants.

Sources and method

Ratio and percentage calculations on this page are volume-balance math. Pesticide use directions, PPE, mixing sequence, and application limits must come from the registered product label. See the U.S. EPA introduction to pesticide labels. For a current example of a dial-rate hose-end sprayer, Ortho's Dial N Spray instructions describe 14 dial settings and direct users to set the dial according to the concentrate product label.