How does ACT Running fit? Size guide and advice

How does ACT Running fit?

The fit of ACT Running garments varies according to their function. The brand does not apply a single rule across the whole collection: a BioPerf t-shirt, a pair of ShellLight shorts or a protective jacket are not built with the same volumes or for the same use.

Several pieces can be chosen in your usual size, while some models are deliberately more fitted or more relaxed. To choose correctly, look at the specific model rather than applying a general recommendation to the entire brand.

You can also browse our full ACT Running selection available at AURA.

BioPerf: which size to choose?

The BioPerf T-Shirt has a straight cut designed for running, without being overly fitted. ACT Running recommends starting with your usual size.

To go further, use the measurement chart shown in this guide. It lets you compare chest width, shoulder width and back length across sizes.

If in doubt, compare these dimensions with those of a t-shirt you already own and whose fit suits you.

How to read the BioPerf size chart

The measurements shown in this guide are those of the garment itself, not body measurements.

For chest width, the garment is measured flat below the armpits. A stated width of 55 cm is therefore the width of the t-shirt laid flat, not a 55 cm chest circumference.

For a reliable comparison, lay a similar t-shirt flat without stretching it, then take the same measurements.

Fit differences across the ACT Running collection

ShellLight

ShellLight shorts have a more fitted cut. If you fall between two sizes, the larger size may give you more room.

The ShellLight 1/4 Zip jacket works differently: its cut is more generous. If you hesitate between two sizes, the smaller one may be the better fit.

ThermoShell and BioFlex

ThermoShell and BioFlex pieces generally fit close to your usual size, but they feel different when worn because of their function.

BioFlex naturally sits closer to the body, since it is designed to provide support during effort. ThermoShell, on the other hand, needs to keep enough room to be layered over a base layer.

BioRip

The recommendation also varies by garment. A BioRip windbreaker may follow a classic cut, while shorts from the same family may be more fitted.

The fabric alone is therefore not enough to determine the size: the construction and intended use of the garment remain decisive.

What to do if you are between two sizes?

For the models currently documented, use these indications as a first reference:

• BioPerf T-Shirt: usual size.
• BioPerf Long Sleeve: usual size.
• ShellLight Short: between two sizes, go for the larger one.
• ShellLight Short 2-in-1: between two sizes, go for the larger one.
• ThermoShell Fleece: usual size.
• BioFlex: usual size.
• ShellLight 1/4 Zip: between two sizes, go for the smaller one.
• BioRip Windbreaker: usual size.
• BioRip Short: between two sizes, go for the larger one.

When a detailed measurement chart is available on this page, use it first: it allows a more precise comparison than a simple “true to size” indication.

Building a complete running outfit

Size choice also depends on how the different layers will be worn together. A close-fitting base layer, a t-shirt, a thermal layer and a jacket do not need the same volume.

To discover ACT Running alongside District Vision and put together a complete outfit, browse our selection of men’s running apparel.

Why AURA uses guides by model

We prefer to centralise sizing information model by model rather than using a generic chart for a whole brand.

This approach takes into account the pattern differences between a t-shirt, a pair of shorts, a base layer or a jacket. The guide displayed on product pages and the charts in this article use the same database, to limit conflicting information.

When new reliable measurements become available for an ACT Running model, they can be added to this guide independently of the other products.

Frequently asked questions about ACT Running sizing

Does ACT Running run small or large?

It depends on the model. BioPerf t-shirts and several technical pieces generally fit true to size, while some ShellLight or BioRip shorts are more fitted. The ShellLight 1/4 Zip, on the contrary, has a more generous cut.

Which size to choose for an ACT Running t-shirt?

For the BioPerf T-Shirt, start with your usual size. To check the volume precisely, compare the chart measurements with those of a t-shirt whose fit already suits you.

Which size to choose for ACT Running shorts?

ShellLight shorts are more fitted. If you hesitate between two sizes, generally go for the larger one. A similar recommendation may apply to the BioRip short.

Which size to choose for an ACT Running jacket?

It depends on the model. The BioRip Windbreaker follows a more standard cut, while the ShellLight 1/4 Zip is roomier. For the latter, the smaller size may be preferable if you are between two sizes.

Do the charts show body measurements?

Not necessarily. When the chart shows garment measurements, the dimensions are taken directly from the piece laid flat. Always check the name of the measurement before comparing it with your own clothes.

Where to buy ACT Running at AURA?

Find the pieces currently available in the ACT Running collection at AURA, as well as our wider selection of men’s running apparel.