Becoming a contract brewer to fill spare tank space

Know your real spare capacity

Spare tank space is not the same as an empty tank on a Tuesday. Work out capacity over a full year. Take each fermenter's volume, divide by the days a typical batch occupies it and you get batches per tank per year. An ale that takes 14 days to ferment and condition gives about 26 turns a year. A lager that needs five weeks gives about ten.

Then subtract your own forecast, including the peaks. Our guide to managing tank space when every beer is selling at once shows how quickly spare capacity disappears in a busy month. Contract beer should fill your quiet months, not compete with your own beer in the busy ones.

Check you are allowed to do it

Brewing a brand you do not own is a licensing question. State excise rules decide whether your licence permits it, how the client's brand is registered and labelled and who is responsible for duty. These rules vary by state and change, so speak to your licensing consultant before you quote anyone. A brewpub licence in particular may limit what you can package and sell outside the premises.

Price for the tank time

The common mistake is to price contract beer on ingredients plus a margin. Your scarce resource is tank time, not malt. A lager that sits in a fermenter for five weeks uses more of your capacity than two ales. Price it accordingly.

Build the price from:

• Raw materials, unless the client supplies them.
• Brewhouse time, labour, utilities and cleaning chemicals per brew.
• Tank days, charged per day or built into a price per style.
• Packaging labour, line time and QC tests.
• An agreed loss allowance, based on your measured losses.
• A margin that pays for the risk and the management time.

Protect your own beer first

Write a scheduling rule into the contract. For example, the client books brews a set number of weeks ahead and you confirm tank space at booking. If your own sales spike, you honour bookings already confirmed but do not take new contract work until capacity returns.

Watch the yeast. Running an unfamiliar strain, especially a diastatic or wild culture, in the same cellar as your house strain is a contamination risk. Many breweries refuse those strains outright or brew them only in dedicated tanks with separate hoses and gaskets.

Agree quality before the first brew

A quality agreement saves both sides from arguments later. It should set the specification with tolerances: original gravity, ABV, colour, bitterness, pH, carbonation and dissolved oxygen at packaging. It should also say who signs off a batch and what happens if it fails. See our guide to the contract brewing quality agreement.

Keep records the client can see: brew sheets, fermentation curves, cleaning logs and lab results. Clients rarely complain about a beer they watched being made properly. They complain when a problem appears and there is no record of what happened.

Choose clients you can live with

The best contract clients order regularly, pay on time and want beer you already know how to make. The worst want a new style every batch, change their order at the last minute and pay late. Ask for part payment in advance, at least for the first few batches. Set clear terms for printed packaging left over if a client cancels.

Pricing tank time, judging capacity across a year and deciding which work to turn down are management decisions more than brewing ones. They are worth getting right before you sign a long contract.

Work out what a turn is worth

Before quoting, estimate what one tank turn earns you on your own beer. Take the litres in a full fermenter, multiply by your margin per litre on your own sales and you have the value of that tank time to your own business. A contract price that earns less than that is only worth taking when the tank would otherwise sit empty.

Do the same sum for the brewhouse and the packaging line. If your canning line already runs four days a week, a contract client who needs two more days may push you into overtime or a second shift. Those costs belong in the contract price. Brewers often forget them because the tanks look empty while the people are already busy.

Keep the first contract short, perhaps six months, with a review at the end. You will learn quickly whether the work fits your brewery.

Your first step

Make a simple calendar of every fermenter for the next 12 months. Fill it with your own forecast brews. The gaps that remain, in tank days, are what you actually have to sell. Price one standard ale against those days before you speak to any client.

Common questions

How should a brewery price contract brewing?

Start from the tank days each beer occupies, then add raw materials, brewhouse time, packaging, QC, losses and a margin for risk.

Is contract brewing worth it for a small brewery?

It can be when tanks sit idle for part of the year, as long as the contract protects your own brewing schedule and quality.

Should I accept a client with a wild or diastatic yeast?

Many breweries refuse, or use dedicated tanks and equipment, because these strains can contaminate the house beers.