How to Choose Premade Fans: D, Diameter and Weight

Course: Premade fans course · Module 2 of 4

When you choose premade fans, taste is only part of the story. Every fan adds up the weight of all its fibres, and a single natural lash has to carry that weight for weeks. In this module you’ll learn how fibre count (D) and diameter combine into weight, how the main industry sources compare, and which combinations are reasonable for each type of natural lash, using the ready-made fans in our shop as worked examples.

Module objectives

Understand why weight and diameter are not the same thing and how fibre count multiplies them.
Use a simple estimate to compare fans with each other and with a classic extension.
Know the equivalences and limits sources suggest, and where they disagree.
Choose curl and length with weight and natural lash direction in mind.

Weight, diameter and fibre count: the key idea

Lash Jungle stresses that weight and diameter are two different concepts. The reason is geometry. If two fibres have the same length and material, their weight depends on their cross-section, and the area of a circle grows with the square of its diameter. Stacy Lash builds this logic into its calculation formula: weight ∝ (diameter/2)² × π × length × number of lashes.

In practice:

A 0.10 mm fibre has roughly 44% of the cross-section of a 0.15 mm fibre.
A 0.07 mm fibre, roughly 22%.
A 0.05 mm fibre, roughly 11%.

Multiply that figure by the number of fibres and you get a theoretical estimate of how many “0.15 classics” the fan weighs. It ignores the adhesive on the base, the material and the curl, so use it to compare fans, not to measure them.

What the sources say

Lash Affair’s rule

Lash Affair’s rule is simple: total fan weight should never exceed a single 0.15 mm classic extension, which it treats as the maximum load for a healthy natural lash. For volume it suggests 2D–3D in 0.07 mm, 4D–5D in 0.05 mm and 6D upwards in 0.03 mm. It is the most conservative source we consulted: it says a 0.07 fibre weighs about half as much as a 0.15, so a 2D in 0.07 would already roughly equal one classic.

Lash Jungle’s guide

Lash Jungle gives broader equivalences: a natural lash that can hold one 0.15 classic can also handle a 2D in 0.10, a 4D in 0.07 or a 9D in 0.05. It also publishes a chart linking some fans to the weight of a classic:

Fan	Weight similar to a classic of…	Suitable natural lashes (Lash Jungle)
—	—	—
3D 0.07	0.12 mm	Any, including fine lashes
3D 0.10	0.18 mm	Strong only
5D 0.07	0.18 mm	Strong only
8D 0.05	0.15 mm	Average or strong
10D 0.05	0.18 mm	Strong only

The brand rates natural lash capacity as: weak, up to the equivalent of 0.12 mm; average, up to 0.15 mm; strong, up to 0.18 mm. By diameter it recommends 0.07 for light volume (3D–6D), 0.05 for full volume (5D–10D) and 0.03 for mega volume (10D–14D or above). On 0.10 it is blunt: for volume, use it only for 2D or 3D, because above that the lashes become “super heavy”.

Why they don’t match

Lash Affair’s and Lash Jungle’s figures don’t line up (for Lash Affair a 2D in 0.07 equals a 0.15 classic; for Lash Jungle it takes a 4D in 0.07). Neither explains how it measured these weights. The sensible approach is to stay at the conservative end of the range, check your lash manufacturer’s own guidance and look closely at each client’s natural lashes.

Guide table for the fans in our shop

This table combines the geometric estimate with what the sources say. It doesn’t replace assessing the natural lash or following the manufacturer’s instructions.

Combination	Theoretical estimate (× 0.15 classic)	What sources say	Suggested use
—	—	—	—
3D 0.05	≈ 0.3	Lash Affair: suitable for fine lashes	Fine or weak lashes
3D 0.07	≈ 0.7	Lash Jungle: suitable even for fine lashes	Fine to average lashes
5D 0.05	≈ 0.6	Lash Jungle: full volume (5D–10D in 0.05); Lash Affair: ≈ one classic	Average lashes
5D 0.07	≈ 1.1	Lash Jungle: like a 0.18 classic, strong only	Strong lashes only
6D 0.07	≈ 1.3	Heavier than a 5D 0.07	Strong lashes only, monitor closely
8D 0.05	≈ 0.9	Lash Jungle: like a 0.15 classic, average or strong	Average or strong lashes
10D 0.05	≈ 1.1	Lash Jungle: like a 0.18 classic, strong only; Lash Affair would use 0.03	Strong lashes only
14D–16D 0.05	≈ 1.6–1.8	Lash Jungle: mega volume is done in 0.03	Not recommended by sources
8D–10D 0.07	≈ 1.7–2.2	Outside Lash Jungle’s 3D–6D range for 0.07	Not recommended by sources
14D 0.07	≈ 3.0	Beyond every limit we found	Not recommended by sources
3D 0.10	≈ 1.3	Lash Jungle: like a 0.18 classic, strong only	Strong lashes only
6D–10D 0.10	≈ 2.7–4.4	Lash Jungle: 0.10 for volume only in 2D–3D	Not recommended by sources

Watch out: high-D fans in 0.10 mm

Our Premade Fan comes in 6D, 8D and 10D, in 0.07 or 0.10 mm, and the Promade Fans Volume Ruso 520 – 600 Fans range also includes 0.10 mm. These combinations deserve a closer look:

By the geometric estimate, a 10D in 0.10 has about 4.4 times the cross-section of a 0.15 classic of the same length; a 6D in 0.10, about 2.7 times.
Lash Jungle recommends 0.10 for volume only in 2D or 3D, and already rates a 3D in 0.10 as suitable for strong lashes only. It specifically asks lash artists whether they use fans like the 5D 0.10 or 10D 0.07, and tells them to check whether clients’ lashes look weaker at every infill, because that means the set is too heavy.
Lash Affair, with its “never more than one 0.15 classic” rule, is stricter still.

Bottom line: we did not find a single source that recommends 6D–10D fans in 0.10 mm on a natural lash, not even a strong one. Based on the sources, you shouldn’t use them for a standard volume set, and certainly not on fine, short, weak or baby lashes. If you want a 6D–10D look, the sources point to finer diameters. If you’re unsure what a specific product is intended for, ask the supplier or manufacturer.

How to assess the natural lash

Before choosing a fan, look carefully at your client’s lashes:

Thickness and strength: thick, healthy lashes can take fuller fans; fine, limp or brittle lashes need a lighter load (Lash Affair).
Length: Lash Affair groups natural lashes as short (under 8 mm), medium (8–10 mm) and long (over 10 mm).
Density: for sparse lashes, Lash Affair advises dropping the D level even if the client wants full volume.
Growth phase: Lash Jungle suggests skipping baby lashes or using thinner, shorter extensions on them.
History: if lashes look weaker at every infill, the set is too heavy (Lash Jungle).

When in doubt, Lash Affair recommends going lighter and building up over several appointments. EyeWiki also describes lash loss caused by the traction of extensions (traction alopecia).

Curl and length

C or D curl

All three ranges come in D curl, and two of them also in C. Divine Lashes describes C curl as the classic choice that suits nearly every client, and D curl as a more dramatic curve for an open-eyed look. According to this source, D works well on straight or downward-facing natural lashes but can be too extreme on lashes that already point upwards; on deep-set eyes, very strong curls can touch the brow bone.

Length

Length adds weight too. Lash Affair advises that an extension should never be more than roughly 2 mm longer than the natural lash it sits on, and reminds you that even though a volume fan is lighter, its combined weight still matters. The 15 and 16 mm lengths in the Pestañas Premade Con Volumen Ruso 320Fans range only make sense on long, strong natural lashes. Before adding length, Lash Affair suggests trying a stronger curl for extra lift.

How to choose premade fans within each range

Premade Fan: according to the sources, the safest option is the 6D in 0.07, on strong lashes only; the 8D and 10D in 0.07 and every 0.10 version exceed the limits we found.
320Fans: the 5D in 0.05 fits the guidance best for average lashes; the 10D in 0.05 and the 5D in 0.07 are for strong lashes only; the 14D and the 10D in 0.07 fall outside the ranges consulted.
520–600: the low dimensions (3D–5D in 0.05, or 3D in 0.07) are the most versatile; as you go up in D or diameter, apply the criteria in the table.

You’ll find all three in our lashes category.

Common mistakes

Choosing by the look rather than the natural lash.
Using high-D 0.10 fans as if they were light volume.
Using the same D across the whole eye, baby lashes included.
Adding length without thinking: more length means more weight.

Module summary

Fan weight depends on fibre count, the square of the diameter and the length.
Lash Affair sets the limit at one 0.15 classic; Lash Jungle gives broader equivalences. The sources disagree, so stay conservative.
Lash Jungle says 0.10 should only be used for volume in 2D or 3D; no source we consulted supports 6D–10D fans in 0.10.
Assess thickness, length, density and growth phase before you choose.
D curl suits straight or downward lashes; length shouldn’t exceed the natural lash by more than about 2 mm.

Self-assessment

Why doesn’t a 4D in 0.07 weigh “four times less” than a 0.15 classic?

Because weight depends on cross-section, which grows with the square of the diameter: each 0.07 fibre has about 22% of the cross-section of a 0.15, so four of them add up to almost one classic (≈ 0.87 times).

According to Lash Jungle, which volume levels can be done in 0.10?

Only 2D or 3D. Above that, the lashes become too heavy.

A client with fine lashes asks for a 10D in 0.10 from the Premade Fan range. What do you do?

Explain that, according to the sources, that combination far exceeds what a natural lash can carry, and offer a lighter option such as a 3D in 0.05 or 0.07.

What sign at infill appointments tells you a set is too heavy?

The natural lashes look weaker and weaker at each infill (Lash Jungle).

On which natural lashes can D curl be too much?

On lashes that already point upwards, according to Divine Lashes.

Note: this online course is for educational and information purposes only and does not replace hands-on, in-person training with a qualified educator. Always follow each product manufacturer’s instructions.

Sources

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