When you first start making cold brew at home, the terms Ready-to-Drink (RTD) and concentrate, along with ratios, can be quite confusing.

This guide will clarify the two primary methods for making cold brew at home, RTD or a concentrate, by detailing the pros and cons of each, helping you master both in your own kitchen.

Understanding the Difference: Strength is Key

The main difference between RTD and concentrate is the coffee-to-water ratio used during brewing.

• Ready-to-Drink (RTD): This coffee is brewed at the strength you want to drink it immediately. You might add a splash of milk or ice, but no extra water is needed. The ratio is generally lower in coffee grounds.
• Concentrate: This is brewed using a much higher ratio of coffee grounds to water, making it very strong, almost like an espresso shot. It should be diluted with water (or milk) before drinking.

Deep Dive: RTD Cold Brew

RTD is often the easiest and most familiar way to brew. It's designed to be enjoyed straight from the brewer. Think of this as the "set it and forget it" method for your daily caffeine fix.

Why Choose RTD?

Pros:

• Simple: No need to measure water for dilution later.
• Consistent: Since it’s ready to go, the flavor is consistent from the moment it's brewed.
• Convenient: If you plan on drinking your cold brew straight, brewing it at RTD strength is the most efficient method.

Cons:

• Takes Up Space: You need to brew (and store) a larger volume of liquid.
• Less Versatile: You can't easily make a super-strong latte without using a lot of the brew. It’s difficult to significantly change the strength of the final beverage.
• Requires More Frequent Brewing: Since you consume the large, full volume of the brew straight for each serving, you will exhaust a batch much faster than a concentrate (which is diluted for each serving), meaning you have to brew more frequently.

How to Brew RTD (Coffee-to-Water Ratio)

For the Ready-to-Drink (RTD) method, here are the key brewing parameters:

• Ratio: 1:12 to 1:16 (Coffee grounds to water). This means for every 1 part of coffee grounds, you use 12 to 16 parts of water.
• Grind Size: Coarse. A coarse grind is essential to prevent over-extraction and bitterness during the long cold brew time.
• Brew Time: 12 to 24 hours in the refrigerator. Use a dedicated cold brew maker (like our Cold Brew System) or simply a large jar with a filtering system.

Example: Using 100 grams of coffee grounds, you would use 1200 ml (or grams) of water for a 1:12 ratio.

Deep Dive: Cold Brew Concentrate

Cold brew concentrate is the powerhouse of home brewing. It's less about the volume and more about the punch, making it the perfect base for maximum flavor and versatility. This is where you master cold brew concentrate at home.

The Benefits of Using Cold Brew Concentrate

Pros:

• Flexibility: You control the strength of your final drink every time. Want a light coffee? Add more water. Want a rich coffee flavor? Use less.
• Economical: Since you dilute it, a single batch goes a long way.
• Perfect for Mixers: Its intensity makes it ideal for mixed coffee drinks, baking, or even cocktails where you want a robust coffee flavor without excess liquid.

Cons:

• Requires Dilution: You must dilute it. Drinking it straight is often too intense and overwhelming.
• More Coffee Beans Upfront: Because concentrates use a much lower coffee-to-water ratio (1:4 to 1:8), they require a significantly larger and more costly amount of coffee beans upfront than an RTD batch.

How to Make Cold Brew Concentrate at Home

Concentrate ratios are much tighter, often ranging from 1:4 to 1:8. A 1:4 ratio is very intense, while 1:8 is a strong, yet more manageable concentrate.

• Ratio: 1:4 to 1:8 (Coffee grounds to water).
• Grind Size: Coarse (Same as RTD).
• Brew Time: 12 to 24 hours in the refrigerator. 
  

Example: Using 100 grams of coffee grounds, you would use 400 ml (or grams) of water for a 1:4 ratio.

Diluting Your Concentrate

This is the most important step! After brewing, you'll mix your concentrate with water (or milk) to reach your desired drinking strength, usually a final ratio of 1:12 to 1:16.

A good starting point for dilution is a 1:1 ratio of concentrate to water. If your concentrate was brewed at 1:6, diluting it 1:1 (one part concentrate, one part water) yields a final drinking strength of approximately 1:12—perfectly balanced!