how big are at 6 weeks?

At six weeks of development, an embryo is typically about the size of a pea, measuring around 1.5 to 2 centimeters (0.6 to 0.8 inches) in length. During this stage, key structures begin to form, including the brain, spinal cord, and heart, which starts to beat. The embryo is beginning to take on a more recognizable shape, with the development of limb buds. Overall, it's a crucial period for early growth and organ development.