Umbrella arc diameter vs straight diameter: the gap across four Davek models

Two listings can both say “40 inch umbrella” and describe different canopies. One quotes the arc, measured over the curve, the other the straight line across. Davek is unusual in printing both numbers on its product pages, so four of its umbrellas show how far apart the two measures sit. This is a reading aid from one maker’s published figures, not a test, and prices are left out.

The four models

Mini and Commuter figures come from Davek’s Mini and Commuter pages, read on 5 November 2026. The Solo and Elite figures come from our October 2026 check of Davek’s pages, which were rate-limited when we tried again.

The gap widens with size, from 4 inches on the smallest to 6 on the two biggest. Davek does not define the terms on the pages we read, but the larger number behaves like a measurement along the curve of the canopy and the smaller like the width in a straight line.

What reviewers measure

Independent figures tend to match the smaller, straight number. Wirecutter, which we read in October 2026, measured the Commuter at 35 inches and the Solo at 37, the same as Davek’s straight diameters. The Guardian’s table, summarised in our spec table sheet, gives 86 cm for the Mini and 112 cm for the Elite, again the straight figures. OutdoorGearLab went its own way: it measured the Elite at 107 cm, about 5 cm under Davek’s 112 cm. Different testers, different tape.

How to use this

1. Find the word. Look for arc, span or diameter next to the number. If a listing gives one number with no word, do not compare it with one that has a word.
2. Compare like with like. Put straight against straight and arc against arc. The size guide on Calm Eden, umbrella sizes explained, covers diameter, arc and folded length.
3. Convert roughly, not exactly. On Davek’s four models, straight is 86 to 89% of arc, so a 40 inch arc is about 34 to 36 inches straight. Another brand may cut its canopy differently.
4. Add folded length. Canopy size tells you cover; folded length tells you whether it fits the bag. Our spec label guide lists the other terms.

One example

XZVZX and Calm Eden share an owner. For its own Haven Umbrella, Calm Eden’s Haven Umbrella folds to 40 cm (15.75 in) and weighs about 390 g, with 30 carbon fibre ribs and a lifetime warranty. The maker gives its open width as about 105 cm without saying whether that is arc or straight, so we do not convert it. It carries a 30 Day Money Back Guarantee that accepts opened or used umbrellas, with free returns. Every order includes a Haven Cover and the Wellness Journal (digital); Buy 2 Get 1 Free adds the UV Charm and the Rain Poncho, and Buy 3 Get 2 Free also adds the Haven SPF 50+ Silk Square Scarf.

For two brands read side by side, Calm Eden’s Davek umbrella review and Blunt umbrella review read what Wirecutter, CNN, Which? and OutdoorGearLab each found.

Short version

• Arc is the bigger number, straight the smaller.
• Davek’s straight diameters are 86 to 89% of its arc ones.
• Compare the same measure, then check folded length.

Sources: Davek Mini and Commuter product pages (5 November 2026); Davek Solo and Elite pages and Wirecutter, as read in October 2026; the Guardian umbrella test and OutdoorGearLab as summarised in our earlier sheets. Reading aid, not a test.