Kitchen Hack: How to Tell the Difference Between a Simmer vs. Boil

From boiling up boxed pasta to tackling the most complicated recipe, odds are, most cooking you do will involve boiling water.

But what’s the difference between a simmer, a gentle boil, and a rolling boil [1]? Thumb through any cookbook and you’ll see recipes calling for different simmering or boiling methods.

Mastering these methods—and knowing which liquid heating technique works best with which recipes—could mean the difference between a successful dish and a culinary disaster. Just follow our simple cheat sheet to cook every dish to perfection.

What is a simmer?

What does a simmer look like?

At a simmer, a few tiny bubbles should form in the water every few seconds. Overall, however, the water shouldn’t be moving very much. To simmer, you’ll usually want to use medium-high heat.

What is a simmer used for?

Simmering is used for melding different flavors together, braising meat, or cooking down soups, sauces, and stocks.

What is a gentle boil?

What does a gentle boil look like?

Like a simmer, a gentle boil shouldn’t involve much agitation in the liquid. Instead, small bubbles should constantly break at the surface, and some larger bubbles should form periodically. You may need to keep a close eye on the temperature to make sure a gentle boil doesn’t turn into a full-on boil.

What is a gentle boil used for?

A gentle boil is used for thickening sauces and soups nicely without too much splashing or mess [2].

What is a boil?

What does a boil look like?

Bringing water or sauce to a boil usually requires high heat. Boiling should constantly produce big bubbles that break at the surface of the pot, releasing lots of steam.

What is a boil used for?

A boil is used for getting hearty vegetables (like potatoes and root vegetables) perfectly tender and cooking hard- or soft-boiled eggs.

What is a rolling boil?

What does a rolling boil look like?

Think of a rolling boil as a boil kicked up a notch or two. Big bubbles should erupt at the surface of the water, and neither stirring nor adding ingredients can slow down the boil. You can also hear the movement of the water at this stage [3].

What is a rolling boil used for?

A rolling boil is used for quickly blanching vegetables and cooking pasta until al dente.

Photo credit: Paul Delmont