Muffett's Filter (Cold?) Brew Coffee Extract Calculator; v1.1

Recipe Preference: Lock N (number of cups)

Ingredients: All Figures Are Approximate

N — number of cups of coffee extract M — strength / mass of coffee (g) per cup V — volume of coffee (ml) per cup; 227g = 8oz / a mug R — mass (g) of water retained by 1g of ground coffee X — total mass (g) of ground coffee W — water required (ml)

Changing X recomputes N
If Lock N is enabled, M is recomputed instead
W / Water is always computed
X=N*M
W=(R*X)+(N*V)

Method

I use broadly the same recipe calculator for filter, cafetiere and cold-brew coffee.
If I am making cold-brew coffee, generally I use filtered water from a kettle which has been boiled for a minute or two and then left to cool for a couple of hours to room temperature. It's your choice.
For cold-brew: gradually add W volume of water at room temperature to X mass of ground coffee, mixing gently but thoroughly. Be aware that the container needs to contain both W volume of water and also X grams of swollen, hydrated coffee grounds, so plan to use a large enough container. Let stand for a few hours at room temperature, or overnight if refrigerated. Filter, possibly dilute, possibly warm, and serve. Gently microwaving the neat extract also works well.
Consider only partially-filling cups (smaller V) and perhaps also making stronger (bigger M) to leave space in mugs for topping up with boiling water before drinking.
Experiment and have fun.