Which is smaller, RBC or sperm?

Sperm cells are smaller than red blood cells (RBCs) when we compare the size of the cell head.

Size Comparison

• Red Blood Cells (RBCs): RBCs in humans are circular and biconcave in shape. Their size is about 6–8 micrometers in diameter. They have no nucleus, which allows them to carry more hemoglobin and transport oxygen efficiently.
• Sperm Cells: A sperm cell has two main parts – a head and a tail. The head measures about 4–5 micrometers in length, while the tail extends about 50 micrometers. However, when comparing just the cell head, which contains the nucleus and DNA, it is smaller than an RBC.

Key Points of Difference

1. Function:
   • RBCs transport oxygen from lungs to body tissues.
   • Sperm cells are male reproductive cells that carry genetic material to fertilize the female egg.
2. Shape:
   • RBCs are round and biconcave.
   • Sperm cells are elongated with a head and a tail.
3. Size:
   • RBC: 6–8 micrometers (larger).
   • Sperm head: 4–5 micrometers (smaller).

Why Sperm is Smaller

Sperm is designed for mobility and efficiency. It carries only the essential genetic material and has a tail for swimming. Its small head helps it move quickly through the female reproductive tract. RBCs, on the other hand, need a larger surface area to carry oxygen and circulate in blood.

Conclusion: Sperm cells are smaller than red blood cells if we compare just the head size. RBCs measure about 6–8 micrometers, while sperm heads are about 4–5 micrometers.