Bantam, Standard or Giant: Chicken Breed Sizes Compared

Our buying guide covers flock size and lifespan, but not how much a full-grown bird actually weighs — and that varies far more by breed than most first-time keepers expect. This guide sets out what four real breed standards say, from a 500-gram bantam hen to a 6-kilogram giant cock.

Adult weights, by breed and source

That's roughly a tenfold spread from the smallest hen to the largest cock — genuinely different animals to house, feed and handle, despite all four being ordinary domestic chickens.

Bantam means a small breed, not a young bird

It's an easy mix-up: a bantam isn't a chick or a juvenile bird, it's a naturally small breed (or a miniature version of a standard breed) that stays small its entire adult life. A Dutch Bantam male never exceeds 20oz — that's its full-grown weight, not a stage it grows out of.

Silkie: a bantam that outweighs a “true” bantam

Oklahoma State University Extension notes something genuinely interesting here: in America, Silkies are classed as bantams, whereas in Great Britain they're classed as large fowl — and by the numbers, a Silkie hen (907g) is nearly twice the weight of a Dutch Bantam hen (510g), despite both wearing the same “bantam” label in the US. The category is about breed standard and show classification, not a guaranteed size band you can assume across every bantam breed.

Jersey Giant: bred for size, slow to fill out

The Jersey Giant was developed in the 1870s in New Jersey specifically to meet demand for a heavy fowl, bred from crosses of Orpingtons, Javas and Langshans. Oklahoma State University Extension notes a practical quirk worth knowing before buying one: Jersey Giants grow a large frame first and don't cover it with meat until around six months old — a genuinely slower maturation than most standard breeds, which is part of why they were never widely used commercially despite their size.

What this means for your plans

• Coop and run space guidance isn't broken down by breed size in the source we used for how much space a chicken needs, so use the same per-bird minimum regardless of breed, and expect a Jersey Giant to feel noticeably more cramped at that minimum than a Dutch Bantam would.
• Budget feed for the breed's actual adult weight with the feed cost calculator — a flock of Jersey Giants eats considerably more than the same headcount of Dutch Bantams.
• Re-read our buying guide for flock size and registration before choosing a breed — those requirements apply the same regardless of which breed you pick.

What we couldn't find

We checked four breeds with clearly published weight standards; we didn't find a single comprehensive table covering every popular backyard breed (Orpington, Plymouth Rock, Rhode Island Red and others each have their own Oklahoma State University Extension page, but pulling every one into this guide was out of scope). If your breed isn't listed here, check its own entry on breeds.okstate.edu directly, or ask the breeder or hatchery you're buying from.

Sources: Oklahoma State University Extension, Breeds of Livestock (Dutch Bantam, Silkie Bantam, Leghorn, Jersey Giant chicken breed pages): breeds.okstate.edu. Sources checked: September 2026.

Common questions

How much do bantam chickens weigh?

It depends on the breed, not just the bantam label. Oklahoma State University Extension gives the Dutch Bantam as under 20oz (567g) for males and under 18oz (510g) for females — genuinely tiny. The Silkie Bantam is bigger despite also being a bantam: the APA standard gives 36oz (1.02kg) for cocks and 32oz (907g) for hens.

Is a bantam just a baby chicken?

No — that's a common mix-up. A bantam is a naturally small breed (or a miniature version of a standard breed), not a juvenile bird. A Dutch Bantam stays under 20oz its whole adult life; it never 'grows into' a bigger bird.

How much do standard-sized chickens weigh?

Oklahoma State University Extension gives the Leghorn, a common standard layer breed, as 6lb (2.7kg) for cocks and 4.5lb (2.0kg) for hens — three to four times the weight of the Dutch Bantam.

What's the biggest chicken breed?

Oklahoma State University Extension describes the Jersey Giant as the largest breed in the American Class, with cocks reaching 13lb (5.9kg) and hens 10lb (4.5kg) — developed in the 1870s specifically to meet demand for a heavy fowl.