FG, SG, AG, Turf and Indoor: Cleat Surfaces Explained

The letters on a cleat box describe the ground the outsole was designed for: FG for firm natural grass, SG for soft and muddy grass, AG for modern artificial grass, TF for older turf, IN for indoor courts. They are not style names. Stud length, stud count and outsole stiffness all change between them, and those decide whether the shoe releases your foot when you turn. Buy the code that matches the field you play on most.

The five codes, precisely

FG: firm ground

Molded, non-removable studs, usually a mix of bladed and conical shapes, for natural grass that is not waterlogged. This is the default cleat and the one most players should own first. The studs are long enough to cut into soil and root, and few enough that each carries real pressure and penetrates.

On a saturated, churned field FG slides, because molded studs cannot reach past the mud to the ground underneath. On artificial surfaces it is the wrong tool, for reasons covered below.

SG: soft ground

Fewer studs, noticeably longer, and on most models screw-in and replaceable. Traditionally metal, though aluminum and polymer are common now. The length is the point: on a churned field the studs punch through the surface slop to firm ground beneath.

The trade is that on hard, dry ground the same studs concentrate your weight onto six or eight points: uncomfortable, unstable and hard on the foot. Replaceable studs are a real feature, since you can swap worn ones instead of retiring the shoe.

AG: artificial grass

Built for modern 3G fields: long synthetic pile with rubber crumb infill. AG outsoles use more studs than FG, each shorter and often hollow. More contact points spread load over a surface with no give, and the shorter length keeps the studs in the pile rather than driving into a base that will not yield.

AG is the newest code and the one most often missing from a store's stock, which is why so many players end up in FG on turf by default.

TF: turf

A dense pattern of many small rubber nubs across the whole outsole, with no distinct studs. TF suits older artificial surfaces: short-pile, sand-filled, or the hard worn carpet at a lot of training facilities. The nubs grip through sheer number and area rather than by penetrating anything, and they survive abrasive surfaces that shred a match cleat. They are also the sensible choice for casual training and small-sided games on hard ground.

IN: indoor

A flat gum rubber outsole with no studs and no tread depth, in the non-marking compound most venues require. The low profile keeps you close to the floor for the direction changes futsal demands, and a flat sole grips a sealed surface far better than studs, which rock and skid.

Code	Surface it is built for	Main risk if used elsewhere
FG	Natural grass, dry to normal	Studs lock into artificial turf and do not release: knee and ankle loading. Slides on soft ground.
SG	Wet, muddy, churned natural grass	Painful and unstable on hard ground. Metal studs banned in many youth leagues.
AG	Modern long-pile artificial grass	Shorter studs give less bite on soft natural grass.
TF	Older, short-pile or sand-filled turf	Little grip on real grass, especially wet grass.
IN	Sealed indoor courts, futsal	No traction outdoors at all.

Firm ground studs on artificial turf are an injury risk

This is worth saying plainly. Wearing FG cleats on artificial turf carries a genuine risk of knee and ankle injury, and it is the most common equipment mistake in the sport.

The mechanism is straightforward. Natural grass and soil fail under load: when your foot is planted and your body rotates hard, the ground tears a little and the studs release. Artificial turf has a compacted, engineered base that does not fail. Long FG studs sink into the pile, wedge against that base, and hold. Your foot stops rotating while the rest of you keeps going, and that load has to go somewhere, which means the knee.

The secondary problem is more mundane: FG studs on turf are painful. Fewer, longer studs concentrate pressure on a surface with almost no give, and a season of that produces sore feet and bruised heels well before anything dramatic happens.

If you play or train on artificial turf, buy AG or TF cleats for it. This is the one recommendation on the page worth spending money to follow.

Metal studs and league rules

Metal soft ground studs are prohibited in many youth leagues and by plenty of adult recreational leagues and facility operators. Some allow metal-tipped studs but not screw-ins, some ban anything metal, and referees at youth level check cleats before kickoff. Rules vary by association, so check your own competition rather than assuming. Turf facilities ban metal almost universally, since it damages the surface, so if your league is on turf the question does not arise.

Which pair to buy first, and can one pair do two jobs?

Buy for the surface you play matches on, which is usually FG, and which is where model choice is widest anyway. See our full guide to choosing soccer cleats for how surface interacts with fit and materials. The second pair should cover your second surface rather than duplicate the first: most players train on turf and play on grass, so a turf shoe is the highest-value second buy, and alternating pairs lets both uppers dry out.

As for one pair covering two surfaces, AG is the only honest crossover: its shorter, more numerous studs work acceptably on firm grass and are safe on modern turf. Every other combination has a real cost. FG on turf is a hazard, TF on grass is slippery, and SG on anything dry is miserable.

Common mistakes

• Assuming FG means all-purpose. It means firm natural ground and nothing else.
• Treating AG as a marketing variant of FG. The stud count and length are genuinely different.
• Buying SG for a wet climate rather than a wet field. Rain does not make a drained field soft.
• Wearing turf shoes for grass matches because they are comfortable. They slide as soon as the grass is wet.
• Not checking stud rules until a referee sends a player off to change.

Questions people ask

What does 3G actually mean?

Third-generation artificial grass: long synthetic fibers with rubber crumb infill between them, the surface most modern all-weather fields use, and what AG outsoles are designed around. Older surfaces are shorter, sand-filled and harder, which is TF territory.

My cleats say FG/AG. Is that real?

Hybrid outsoles are a genuine compromise, usually a pattern nearer AG with slightly longer studs. Safer on turf than a true FG cleat, less capable on soft grass. If nearly all your play is on turf, a dedicated AG or TF shoe is still better.

Do I need a different size across surface types?

Often, yes. Turf and indoor shoes run differently from a grass cleat in the same brand. Try each pair on rather than repeating a number, using the method in our guide to cleat fit and sizing.