Eyelash Extensions: Which Curl and Length is Best

by Joan Wong

As a lash tech, you should have a wide variety of eyelash extensions at your disposal. This way, you will always be prepared for clients who want different lash extensions. During your client consultation you will be able to decide which extension to use based on the curl, length, and thickness.

Remember, clients will have different preferences and will want a specific type of look or set. But don’t worry! Here are the common eyelash extensions the majority of your clients will go for.

Types of lash curls for eyelash extensions

Because of the increasing demand for eyelash extensions, the need for different variations to meet the different eye shapes arises. There are a wide variety of eyelash extensions depending on the curl type. It's important to remember that manufacturers may label their curls differently and have slight variations in the overall curvature but, generally speaking, across most manufacturers these variations are easy to differentiate.

Eyelash extension curl types. Cartel Lash

As a lash tech, here are the most common curls you need to know when buying eyelash extensions supplies:

B Curl

B curl lash extensions are pretty simple but provide a bit of curl. Not too exaggerated and not too flat. The finish look is natural with a soft curl. They are ideal for clients with straight natural eyelashes that point straight or slightly upwards.

They are also used by lash artists for inner corner lashes. They are not ideal for clients with heavily downward eyes or natural lashes.

C Curl

Also known as the common curl, C curl lash extensions have a curl closer or similar to natural lashes. They are ideal for clients with a slight curl in their natural eyelashes. 

If your client has straight natural eyelashes, when you use C curl, it will give them a doll or an open eye effect. Meanwhile, if your client has slightly downward angled eyelashes, C curl will provide a slight lash lift effect.

However, if your client has heavily downward angled eyelashes, do not use C curl, as you will need a more pronounced curl. I recommend using a CC or D curl.

Woman with finished eyelash extensions. Cartel Lash

CC Curl

CC curl is a hybrid curl. It tends to be a happy medium between a C and D curl. This type of curl has the same base as the C curl and finishes with a dramatic flair of a D curl. 

This curl works great to add lift to the outer edges of your set, especially with clients that have downward or droopy looking eyes. 

D Curl 

D curl provides more drama and has a visible curl. If your client has straight or downward angle natural eyelashes, go for D curl. 

When you use D curl lashes on clients with downward angle natural lashes, it will have an open eye effect. While when used on clients with horizontal angled natural lashes, it gives a lovely doll eye effect.

It is very important not to use D curl lash extensions on clients with upward angle natural lashes and hooded eyelids because there is a possibility that it will poke your clients’ eyes (depending on the length you use).

J Curl 

J curl lashes are the most natural curl on our list and a must have in your lash supplies. This is ideal for clients with straight natural lashes pointing straight or upward. If your client is looking for an everyday natural look, the J curl should be considered.

Do not use J curl lash extensions on clients with heavily hooded angle natural lashes.

L+ Curl Lashes

L curl has the most curl on our list. It has a flat base with a harsh upward curl. It is ideal for clients with deep set eyes, hooded eyes, and droopy eyelids. 

If your client wants drama, add L+ curl lashes to your list of curl types you can consider. It also offers the most visible eyelid lift effect.

But keep in mind, do not use L+ curl on clients with downward angle natural eyelashes.

Choosing the style and length for eyelash extensions

When you are deciding the eyelash extensions’ length and diameter (thickness) you need to first consider the condition of your client’s natural eyelashes. Too heavy of a set on unhealthy or brittle natural eyelashes will cause breakage. This is not good for your client’s natural eyelashes.

Eyelash extension thickness and length guide. Cartel Lash

Here are some guidelines to help guide your client as their lash tech:


It is very normal for clients to want long lashes. However, clients have different natural eyelash conditions which will determine the best and most practical length to work with. 

Remember, it is your responsibility to guide and explain to your clients why a certain length is more ideal for the condition of their natural lashes. It is super important to protect the health of your client’s natural lashes and to avoid premature fallout or damage to their natural lashes by picking a length that wont hinder its growth cycle. 

For clients with hooded or droopy eyelids, you can go for lash extensions that are slightly longer than their natural lashes. Because their eyelashes tend to hide under their eyelids when they open their eyes.

Keep in mind, the stronger the curl of the lash extensions are, the shorter they will look. Make sure to choose the length of the eyelash extensions based on the curl type you are going to use.

Diameter or thickness

The set your client wants will generally determine the diameter you will use. For classic sets you will use 0.15 extensions (in special cases you may need to use 0.10) and for volume sets you can use 0.07, 0.05 or 0.03 extensions. 

When picking the diameter for volume there are a few factors to consider, how full your client wants their set, the health of their natural lashes and the number of extensions per fan. Clients with healthy lashes will be able to support more weight and bigger fans, having said that, fuller volume sets require the use of thinner extensions like 0.03’s. 

For Classic Sets, you would want to compare the thickness of your client’s natural eyelashes with your lash extensions. This is the best way to determine and estimate the thickness or diameter of the eyelash extensions you will use for your client.

Lifestyle and preference

More and more people now realize the importance of being active. A lot of people are wondering if they can have eyelash extensions even though they always run, swim, or work out. The short answer is yes, of course, they can!

As a lash tech, it is your responsibility to explain to your clients that lash extensions are not as fragile as they think they are. Make sure to ask your clients what type of exercises they do and how often they do them. Also, it is your duty to inform them of how to take care of their lashes after an application with the proper lash supplies so their extensions don’t get damaged and fall off prematurely.

Eyelash extensions aftercare instructions for clients. Cartel Lash

For example, for those clients who like to run, jog, hike, and anything that makes them sweat, it is very important to let them know NOT to get their eyelash extensions wet 24 to 48 hours after the application. After that waiting period, they can start exercising as long as they make sure to clean their eyelashes daily. Explain the importance of having a daily aftercare routine.

For swimmers, DON’T get your eyelashes wet for 24 to 48 hours after the application. This is very important. And whatever happens, let your clients know not to rub their eyes. They can wear goggles in order to protect their eyes from irritation. 

It is very important to consider your client’s lifestyle and preferences when choosing eyelash extensions. Always consider their natural eyelashes first before giving any advice and starting application.

For all your lash supplies, find everything you need at Cartel Lash or call us 📞 (604) 437-0011 to speak to a product specialist for recommendations!