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Size guide for Aku
AKU Size Guide
AKU is an Italian brand founded in Montebelluna, in the heart of the Italian sports shoe district. A specialist in outdoor footwear since 1982, AKU produces only shoes — no textiles. All its shoes are made in Europe (Italy and Romania). AKU is known for its wide anatomical fit, generous toe box, and shapes based on real feet. This guide covers the entire outdoor range available on Alpinstore: lightweight hiking, trekking, approach, mountaineering, fast-hiking, and the Wide versions.
Outdoor ranges: Slope, Bellamont, Alterra, Tengu, Tribute, Flyrock, Trekker Lite, Rapida, Omnia, Ultralight, Link, Adapta, Rocket.
Alpinstore Return Policy
- AKU fits true to UK sizes. Your usual EU size is suitable in the vast majority of cases. No need to take a size up.
- Wide and generous fit. AKU uses anatomical shapes with a wide toe box. Wide or duck feet are very well accommodated. If you have very narrow feet, consider going half a size down.
- Half sizes available on most models (EU 37.5 / 39.5 / 41.5 / 42.5 / 44.5 / 46.5). If you are between two sizes, the AKU half size often fits perfectly.
- Wide version available on certain models (Trekker Lite III Wide GTX). Reserved for very wide feet. Take your usual size in Wide.
- Trekking and loaded hiking: take your usual size with technical hiking socks. No need to go up a size as with other brands.
- Try at the end of the day with the socks you will use for hiking. The foot naturally swells throughout the day.
AKU Size Conversion Chart
AKU is made on lasts based on UK sizes. The table below is the official EU / UK / US conversion with foot length in cm (Mondopoint). This table applies to all AKU outdoor models available on Alpinstore.
| EU | UK | US Men | US Women | Foot Length (cm) |
|---|---|---|---|---|
| 35 | 3.0 | 4.0 | 5.5 | 22.0 |
| 36 | 3.5 | 4.5 | 6.0 | 22.5 |
| 37 | 4.0 | 5.0 | 6.5 | 23.0 |
| 37.5 | 4.5 | 5.5 | 7.0 | 23.5 |
| 38 | 5.0 | 6.0 | 7.5 | 24.0 |
| 39 | 5.5 | 6.5 | 8.0 | 24.5 |
| 39.5 | 6.0 | 7.0 | 8.5 | 25.0 |
| 40 | 6.5 | 7.5 | 9.0 | 25.3 |
| 41 | 7.0 | 8.0 | 9.5 | 25.8 |
| 41.5 | 7.5 | 8.5 | 10.0 | 26.2 |
| 42 | 8.0 | 9.0 | 10.5 | 26.7 |
| 42.5 | 8.5 | 9.5 | 11.0 | 27.0 |
| 43 | 9.0 | 10.0 | 11.5 | 27.3 |
| 44 | 9.5 | 10.5 | 12.0 | 27.8 |
| 44.5 | 10.0 | 11.0 | 12.5 | 28.2 |
| 45 | 10.5 | 11.5 | 13.0 | 28.7 |
| 46 | 11.0 | 12.0 | 13.5 | 29.2 |
| 46.5 | 11.5 | 12.5 | 14.0 | 29.5 |
| 47 | 12.0 | 13.0 | 14.5 | 30.0 |
| 47.5 | 12.5 | 13.5 | — | 30.5 |
| 48 | 13.0 | 14.0 | — | 31.0 |
Source: official AKU grid (Varusteleka / aku.it / aku.co.uk). Available sizes vary by model. The foot length (cm) corresponds to Mondopoint — measure your foot and refer to the corresponding column.
AKU Fit Characteristics by Range
Slope — Beginner and Leisure Hiking
Standard fit, medium volume. Usual size. The historical model of AKU — 30 years of success. Lightweight and comfortable for daily outings of medium difficulty.
Models: Slope GTX, Slope Micro GTX, Winter Slope Max GTX. Available in low and mid-cut. Vibram sole.
Bellamont — Versatile Hiking
Anatomical fit, generous toes, very comfortable. Usual size. Ideal for urban use and outdoor leisure activities. Careful design in suede or nubuck.
Models: Bellamont III Suede GTX, Bellamont III Mid GTX, Bellamont V Low GTX. Men and women.
Alterra — Technical Heavy Trekking
Wide and anatomical fit, very robust. Usual size. Designed for long and demanding days of walking on varied terrain, including snowshoeing. Thick leather upper, stone guard, exclusive Vibram Weave sole with Elica system.
Models: Alterra GTX, Alterra Lite GTX. Bestsellers at Alpinstore.
Tengu — Fast-hiking and Versatility
Lightweight and dynamic fit, medium-fine volume. Usual size. Designed for dynamic situations on difficult terrain. Innovative materials (recycled microfiber, Gore-Tex). Vegan-friendly.
Models: Tengu GTX, Tengu Low GTX, Tengu Lite GTX. Men's and women's models.
Trekker Lite — Versatile Trekking
Versatile fit, medium volume. Usual size. Among the most versatile models in the trekking category. Wide version available for very wide feet — same size in Wide as in standard.
Models: Trekker Lite III GTX, Trekker Lite III Wide GTX (men and women). The Wide version is recommended for a forefoot width of more than 100 mm.
Flyrock — Fast-hiking and Lightweight Trail
Lightweight fit, medium volume. Usual size. Shoe for fast hiking and dynamic off-road activities. Traction, protection, and high cushioning. Vibram Traction Super sole with EVA High Cushion / High Rebound.
Models: Flyrock GTX. Low cuts, fast approach.
Tribute — Approach and Trail
Fitted fit, medium-fine volume. Usual size. Technical approach and trail model. Suitable for fast hikes on varied terrain.
Models: Tribute GTX. Men and women.
Omnia, Ultralight, Rapida, Link — Lightweight and Urban Hiking
Comfortable fit, medium volume. Usual size. Versatile models suitable for lightweight outdoor activities, e-biking, urban adventures. Uppers made from recycled materials.
Models: Omnia V Light GTX, Ultralight Micro GTX, Rapida, Link GTX. Men and women.
Rocket — Mountaineering and Technical Approach
Precise and technical fit, medium-fine volume. Usual size. Designed for technical approach and mountaineering. Dual Fit System on certain models: double lacing allowing to reduce volume at the toe for maximum precision on rock.
Models: Rock II GTX (Dual Fit System). Recommended for rock mountaineering approaches.
Adapta — Adaptive Comfort
Very wide fit with adaptable upper. Usual size. Designed for difficult-to-fit feet, conformation issues, or bandaged feet. Internal volume adaptation technologies.
Models: Adapta GTX. Solution for orthopedic or very wide feet.
AKU Technologies Explained
Gore-Tex
Waterproof and breathable membrane. Present on almost all AKU models (GTX suffix). Guarantees dry feet and good moisture wicking.
Vibram
High-performance rubber sole. AKU uses several Vibram compounds depending on the models: Traction Lug MegaGrip (versatile), Traction Super (fast-hiking), Weave (technical trekking).
Elica Natural Stride System
Midsole system that follows the natural movement of the foot for optimal walking comfort. Present on Alterra models and high-end.
Air8000
Ventilation system integrated into the midsole. Promotes air circulation inside the shoe to maintain a cool and dry interior environment.
Dual Fit System
Double lacing system on the Rock II model. Standard lacing for comfortable approach walking. Second lacing (independent) to reduce volume at the front of the shoe during rock passages.
Dynamic Fit System
System that adapts the upper to the shape of the foot. Ensures optimal support without pressure points on technical models.
BOA
BOA lacing system on certain models: precise tightening dial replacing traditional laces. Quick tightening and loosening with one hand.
Wide Version: for Wide Feet
AKU offers a Wide version (wide fit) on certain models, mainly the Trekker Lite III Wide GTX (men and women). The Wide version is intended for feet with particularly wide forefoot.
How to know if you need a Wide version? Measure the width of your forefoot at the level of the phalanges (the widest part). If this measurement exceeds 100 mm, the Wide version may suit you. If you regularly experience compression or lateral pressure with standard shoes, opt for the Wide.
Size in Wide: take exactly the same EU size as in the standard version. The Wide version is not longer, only wider in the forefoot and toe box.
How to Measure Your Foot to Choose an AKU Shoe
1. Measure the Length
- Place your foot on a sheet of paper, heel against a wall.
- Mark the tip of the longest toe with a perpendicular line.
- Measure the distance between the wall and the line in cm.
- Do both feet and keep the larger one.
- This value is your Mondopoint — refer to the table above.
2. Measure the Width
- Place your foot flat on a sheet of paper.
- Mark both sides of the forefoot at the widest point.
- Measure the distance between the two marks in mm.
- Less than 95 mm: narrow or normal foot → standard model.
- More than 100 mm: very wide foot → consider the Wide version.
3. Fitting Tips
- Try at the end of the day (foot swollen).
- Wear the socks you will use for hiking.
- Lace completely and walk in the shoe before deciding.
- On descents, the toe should not hit the front.
- The heel should stay well secured without rubbing.
FAQ AKU Size Guide
Does AKU run large or small?
AKU fits true to UK sizes on which its shoes are designed. The fit is generous, with a wide toe box. Your usual EU size is the right one. Unlike some Italian brands where it is advised to take a size up, this is not necessary with AKU. If you have a very narrow foot, a half size down may be considered.
Does AKU offer half sizes?
Yes. AKU offers half EU sizes on most of its models: EU 37.5 — 39.5 — 41.5 — 42.5 — 44.5 — 46.5. If you are exactly between two sizes, the AKU half size is often the ideal solution. Availability of half sizes varies by model — check the product sheet.
Does AKU offer shoes for wide feet?
AKU stands out from many brands with its naturally wide and generous fit, suitable for most feet. For very wide feet (forefoot wider than 100 mm), AKU offers the Wide version on certain models, notably the Trekker Lite III Wide GTX. Take the same EU size in Wide as in standard.
What is the difference between men's and women's sizes at AKU?
AKU designs its shoes primarily based on activity rather than gender. The EU sizes are the same for both — only the US conversion differs (US women's sizes are 1.5 to 2 sizes above US men's sizes for the same EU). Measure your foot in cm and refer to the table. Some women's models have a slightly refined internal volume.
What is AKU's Dual Fit System?
The Dual Fit System is present on AKU's Rock II model. It consists of a double independent lacing: the first lacing provides standard comfort for approach walking. The second lacing, located at the front of the shoe, allows reducing the volume in the toe box for maximum precision during technical rock passages. By tightening only the second lacing, the shoe transforms into a technical approach shoe.
Should I take a size up for hiking with a loaded backpack?
No, with AKU it is generally not necessary. The wide and generous fit of AKU already incorporates enough reserve for foot swelling and technical socks. Take your usual size. If you wear very thick socks (like ski socks), an additional half size may be considered, but stick to your size for standard hiking socks.
Does AKU offer orthopedic insoles?
AKU offers replacement insoles (footbeds) as well as the Adapta GTX model designed for feet requiring adaptive internal volume. If you use thick orthopedic insoles, consider an additional half size to maintain internal volume comfort.
The AKU size chart is based on the official AKU grid (sources: aku.it, aku.co.uk, Varusteleka). AKU produces only shoes — no textiles or gloves. The availability of sizes and models varies by season. In case of hesitation, consult the product sheet on Alpinstore and take the larger size.
