Dilution Ratio Calculator
Enter a concentrate-to-diluent ratio from your own reference source, plus one known volume, to scale it to a full batch.
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Before any chemistry: safety
- Read the safety data sheet first. Get the current safety data sheet for every chemical before you open it, and follow its handling, storage and first-aid sections. The arithmetic on this page does not replace it.
- No flame or spark near ether or collodion. Collodion is carried in ether and alcohol. Ether is extremely flammable, its vapor is heavier than air and can travel along a floor to an open flame, a pilot light or a spark. Work with good ventilation, keep every ignition source out of the room, and keep containers closed.
- Gloves and eye protection for silver nitrate. Silver nitrate causes severe skin burns and serious eye damage. Wear chemical-resistant gloves and splash goggles whenever it is open, and know where the eyewash or clean running water is before you start.
- Never use a cyanide fixer. Potassium cyanide appears in period texts as a fixer. It is fatal if swallowed, inhaled or absorbed through skin, and it releases hydrogen cyanide gas on contact with acid. Never use it: modern practice fixes with sodium thiosulfate.
- Acid goes into water. When a label tells you to dilute an acid, add the acid slowly into the water, never water into the acid, so it cannot boil and spit.
- Away from children, food and pets. Store chemicals locked, labeled and out of reach of children and pets. Never use food or drink containers, and keep the work area apart from anywhere food is prepared or eaten.
- Silver waste is hazardous waste. Spent solutions carrying silver are very toxic to aquatic life. Do not pour them down a drain; collect them and dispose of them under your local hazardous-waste rules.
Learn wet-plate chemistry in person from an experienced instructor. This site gives no formulas or procedures.
Scaling a ratio, not prescribing one
A dilution ratio splits a total volume proportionally between two parts. Given a ratio of a parts concentrate to b parts diluent, the concentrate share of any total volume is simply a / (a + b), and the diluent share is the remainder. This calculator applies exactly that arithmetic to whichever volume you already know.
It is deliberately generic: it works the same whether you're scaling a photographic solution, a cleaning solution, or any other liquid described by a documented ratio. It does not look up, suggest, or validate what the two parts should actually be.
Frequently Asked Questions
Where does the ratio come from?
From your own reference source — a manufacturer's label, a datasheet, or an archival reference. This calculator does not tell you what to dilute or in what proportion; it just does the proportional arithmetic once you already know the ratio, such as 1+4 or 1:9.
What does '1+4' or '1:9' actually mean?
Both describe a ratio of concentrate to diluent parts. "1+4" (five total parts) and "1:9" (ten total parts) are common shorthand across photographic and darkroom literature — this tool treats the two numbers you enter as the concentrate part and the diluent part respectively, regardless of which notation your source uses.
Can I work backward from how much concentrate I have?
Yes — switch "I know my…" to "Available concentrate volume" and the calculator scales the ratio up to tell you the maximum total batch (and matching diluent amount) that concentrate supports, which is useful when you're trying to use up a partial bottle without waste.
Is this safe to use for any chemical dilution?
This tool only performs ratio arithmetic — it has no information about what a given chemical is, how hazardous it may be, or how to handle it safely. Always follow the safety data sheet and handling instructions for whatever you're actually working with, and never treat this calculator as chemical-safety guidance.
Educational reference tool only — plain ratio arithmetic on a ratio you supply. Not chemical formulation or a complete safety guide; always follow the safety data sheet for any material you actually handle.