Guide

2V vs 3V vs 4V vs 5V geodesic dome plans

Frequency is the single choice that changes a geodesic dome build the most — more than diameter, more than covering. It's how many times each face of the base icosahedron gets subdivided into smaller triangles before the whole thing gets pushed out into a sphere.

Every geodesic dome starts from the same 20-sided shape (an icosahedron). “Frequency” is how finely each of those 20 triangular faces is cut up before the vertices get projected onto a sphere. 1V is the icosahedron itself, un-subdivided. 2V splits each edge in two, 3V in three, and so on. Higher frequency means more struts, more strut classes (different lengths), and a rounder-looking dome; lower frequency means fewer, longer struts and a more faceted, angular look.

What changes as frequency goes up

	Lower frequency (2V)	Higher frequency (4V–5V)
Strut classes	Fewer, simpler	More, more cut variety
Panel/hub count	Fewer, larger panels	Many more, smaller panels
Sphere look	Faceted, angular	Smooth, rounder
Cost per m² of floor	Generally lower	Generally higher
Typical use	Greenhouses, small shelters	Habitable domes, large event spaces

2V — the simple end

The fewest strut classes and the fewest parts. Good for smaller structures where you want the least cutting and assembly labor, and where a more angular look is fine — garden domes, small greenhouses, temporary shelters. It struggles to look “round” at larger diameters; the facets get visually large.

3V — the default for a reason

The balance point most calculators and kits default to, and DomeFab's default too. A 3V 5/8-sphere dome is a well-tested shape: for example, at a common size it works out to 165 struts across 3 classes (30 of one length, 55 of another, 80 of a third). Enough classes to look genuinely spherical, few enough to cut and sort without a spreadsheet.

4V and 5V — for bigger, or for looking rounder

Once a dome gets large enough that a 3V facet would be a wall-sized flat panel, going to 4V or 5V keeps the panels a manageable size and the sphere looking smooth. This is the range for habitable domes past roughly 9–10 m, and for event or exhibition structures where the shape itself is part of the design. The tradeoff is real: more strut classes to keep straight on site, more hubs or panel edges to assemble, and a higher parts cost for the same floor area.

Class I vs. triacon (Class II)

Frequency is one axis; the other is how the sphere gets divided. Class I (the default, and what most calculators use) divides each icosahedron face directly. Triacon — Class II — divides the sphere into rhombic units first, using even frequencies, and produces a different panel pattern that some panelized builders prefer for flatter, more uniform triangles. DomeFab generates full plans for either.

How to actually decide

Rather than pick frequency from a rule of thumb, open the studio, set your real diameter, and toggle between 2V, 3V, 4V, and 5V. The 3D preview, strut count, and cost estimate update instantly for each — so you're comparing your actual dome, not a generic table.