Ice
Ratio
How much ice, how much drink, and how long it stays cold.
Quick picks
Saved on this phone only.
Your drink
Your cup
Where & how long
Settings: units & freezer
Units Freezer temperatureStep 1 · Brew it over ice
The answer
How full of ice?
"First sip" is the % of the drink that's melted ice once it's chilled. "If nursed" is by the end of your time.
How the math works
The tool balances heat. Your drink gives up heat to chill down; the ice soaks it up by warming from freezer temp to 32°F and then melting (melting is the big one, about 80% of ice's cooling power). After that, heat keeps leaking in from the room through the cup, melting more ice. Insulated cups, shade, and lids slow that leak way down.
With ice in it, a drink settles around 33–39°F no matter what. Smaller ice (crushed, nugget) gets it colder, faster, but melts into the drink faster too. Ice shape doesn't change how much heat leaks in; it changes how fast the drink chills and how cold it sits.
The recommendation is the least ice that keeps it cold the whole time with a little left over, so you get the most drink and the least watering-down. Numbers are good estimates, not lab results.