Dilution Calculator

Safe handling when mixing concentrates

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

• Add concentrate to water, not water to concentrate. Pouring water into a concentrated chemical can cause violent splashing, heat generation, or foaming. Always put water in the container first, then add concentrate slowly while stirring.
• 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.
• Label your container. If you pre-mix and store diluted solution, always label it with the product name, dilution ratio, and date. Never store diluted chemicals in unlabeled containers or food/drink bottles.
• 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

A hose-end sprayer has a jar (reservoir) that sits below the spray head. As water flows through the head, it creates a siphon that draws concentrate from the jar and mixes it at a fixed siphon ratio. The most common siphon ratios are 16:1 (16 parts water per 1 part concentrate) and 20:1, though some sprayers have an adjustable dial.

Why hose-end dilution is different from tank mixing

With a standard sprayer tank, you mix concentrate directly into the full volume of water. With a hose-end sprayer, you fill the jar with undiluted concentrate and the sprayer dilutes it automatically as you spray. This means:

• You must account for the siphon ratio when filling the jar — not the label rate directly.
• The jar contains much more concentrated product than a tank sprayer would.
• The coverage area depends on the jar size, siphon ratio, and your walking speed.

The hose-end dilution formula

To find how much concentrate to put in the jar, the key question is: what final concentration do I need to achieve after siphoning?

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 above does this calculation automatically. Enter your three values and it returns the exact amount to add to the jar plus how many gallons of finished spray the jar will produce.

Common hose-end sprayer siphon ratios

⚠️ Siphon ratios vary significantly by model. Always verify against the physical sprayer, not an assumed value. An incorrect ratio will result in under- or over-dosing.

How to make a dilution: step-by-step

The calculator gives you the right amounts. Here is the correct process for actually making the dilution safely and accurately — fill order matters, and measuring technique affects whether your result is correct.

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. Fill the container with roughly half the required water first. This ensures the concentrate has a large volume of water to disperse into the moment it is added, which reduces foaming and prevents localized high-concentration zones at the bottom of the container.
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 the concentrate to the water slowly, while stirring or agitating. Do not pour water into the concentrate. If using a backpack or boom sprayer with an agitator, engage it before adding concentrate.
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.