Maybe you’ve heard of key limes, but aren’t quite sure what they are, where to find them, or how to cook with them. You’re not alone! Although key lime pie is well known, the limes themselves are more of a mystery to the average home cook.

We’ll take you through everything you need to know about key limes: what key limes are, how they differ from regular limes, how they taste, how to juice them, how to store the juice, and what you can use to replace key lime juice.

A key lime cut in half on a white background, with whole key limes behind the halves.
Want to save this recipe?
Get this sent right to your inbox, plus great new recipes weekly!

Table of Contents

What are key limes?

Key limes are a versatile citrus fruit whose juice is delicious in desserts, drinks, and even savory dishes. You might be most familiar with them in the context of key lime pie, but these small fruits with BIG flavor can add a sweet-tart bite to many different recipes.

Key limes, also known as Mexican limes or West Indian limes, are rounder and much smaller than regular limes. They are named after the Florida Keys, where they were first cultivated in the 19th century. Key limes are typically harvested when they are still green and are about the size of a golf ball.

When ripe, key limes should be soft when squeezed, heavy for their size, and can be green, yellow, or some combination of the two.

Two different limes next to each other: a small yellow key lime on the left, and a larger green Persian lime on the right.

How are key limes different from regular limes?

“Regular” limes, the kind most often found in the average American supermarket, are also known as Persian limes.

When you think of what a stereotypical lime looks like, chances are you’re thinking of a Persian lime. They have dark green skin, the characteristic oval shape with tapered ends, and can range in size from 2-4 inches or more.

Key limes are much smaller and rounder than regular limes. The average key lime weighs about 3/4 ounce, and it takes 18-20 key limes to yield a cup of juice. In contrast, a medium Persian lime weighs about 3 ounces, and it takes 5-6 regular limes to yield a cup of juice.

In addition to the size difference, key limes also have a thinner skin and a higher acidity level than regular limes, which gives them a more intense and tart flavor.

Photo comparing two different limes next to each other: a small yellow key lime on the left, and a larger green Persian lime on the right.

What do key limes taste like?

Key limes have a flavor that is different from regular limes. They are more acidic and have a more intense, tangy taste – more “lime-y,” if you will. Some people describe the flavor of key limes as slightly sweet with a hint of bitterness. They also have a floral aroma that is more noticeable than regular limes.

These differences shine in recipes like limeade, where the lime flavor is really the star. When used in cooking recipes, where the lime juice is mixed with other ingredients, it’s harder to identify key lime’s unique flavors.

Where do you find key limes?

This depends on where you live! If you are near a citrus-growing region like the Florida Keys, they may be easy to find and plentiful in any grocery store.

I live on the West Coast, where they are much less common. I have the best luck finding them in Mexican supermarkets, and occasionally at high-end grocery stores (where they charge a small fortune for these small fruit!).

Hand holding a small key lime above an assortment of key limes and regular limes.

How do you juice key limes?

Juicing key limes can be a bit tricky due to their small size and thin skin. However, there are a few tricks you can use to get the most juice out of your key limes.

Three photo collage showing how to prepare limes for juicing.

Prepare the limes

  1. Before juicing, try firmly rolling the limes on a hard surface, such as a countertop, to help burst the membranes and release the juice.
  2. Another option, which you can do in addition to or instead of rolling, is to microwave the limes for a few seconds, like 5-8 seconds at a time, to soften them before juicing.
  3. After the limes are sliced, you can also take a knife and make small cuts in the segments to pierce the membranes and yield more juice.
Hand juicing a key lime on a white marble background.

Juice the limes

Once softened, cut the limes in half and use a juicer or citrus reamer to extract the juice. I prefer a countertop juicer, as I find a reamer difficult to use on such small, thin-skinned fruits.

Note: If you want to zest your limes, make sure you do so before cutting and juicing them!

Key lime juice in a small glass jar, with lime halves and a citrus reamer in the background.

How do you store key lime juice?

Freshly squeezed key lime juice can be stored in an airtight container in the refrigerator for up to a week. I recommend using glass containers (jars or bottles) rather than plastic.

It can also be frozen for longer storage. To freeze key lime juice, pour it into an ice cube tray and freeze until solid. Once frozen, transfer the key lime juice cubes to a freezer-safe container or bag, and store in the freezer for up to three months.

How many key limes does it take for 1 cup of juice?

This can vary depending on the ripeness, size, and juiciness of your fruit, but as a general rule, you will need approximately 18-20 key limes for 1 cup of juice.

Close-up of two halves of a cut-up key lime.

Can you substitute regular lime juice for key lime juice?

Yes! If you don’t have fresh key lime juice available, fresh regular lime juice is the next best thing. In most cases, after other ingredients are mixed in, the swap will be barely noticeable, if at all.

You also have the option of using bottled key lime juice, but in my opinion, fresh juice is always strongly preferred. The processing that goes into making lime juice shelf stable gives it an overly harsh and artificial flavor.

What else can you use to substitute for key lime juice?

No limes anywhere? No problem! These won’t be perfect matches, but depending on the recipe, one of these might work as a lime juice substitute in a pinch:

  • lemon juice
  • tart orange juice
  • grapefruit juice
  • apple cider vinegar
  • white wine vinegar
  • lime or lemon oil
Pouring key lime filling into a graham cracker crust.

What to bake with key lime juice

Ready to get baking? Use lime juice in one of these delicious citrus-based recipes:

Close-up shot of Key Lime Pie on a white plate.

Key Lime Pie

 This authentic Key Lime Pie recipe is easy and delicious! It has a buttery graham cracker crust and a sweet-tart creamy filling, bursting with fresh lime flavor.
View Recipe
Outside edge of Lime-Coconut Pie, finished with whipped cream, lime slices, and green Sixlets.

Lime-Coconut Pie

This Lime-Coconut Pie is part of a long tradition of Southern-style baked custard pies. The filling is baked until it’s firm enough to slice, but it still has a creamy, custardy texture with a chewy top layer from the shredded coconut.
View Recipe

Meet Elizabeth!

Hi, I’m Elizabeth — a trained pastry chef, cookbook author, video instructor, and your new Baking BFF! I’m going to teach you everything you need to know to be a sugar hero. ❤️

Related Recipes

Leave a comment

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.