Egg Weight During Incubation

🥚 What Is Egg Weight Loss During Incubation?

As an egg incubates, it naturally loses water through its porous shell. This water loss is essential — it allows the air cell to grow, which the chick needs for breathing just before hatching.

The egg’s total weight will gradually decrease over the 21-day incubation period.

📉 How Much Weight Should an Egg Lose?

A fertilized egg should lose approximately 12–14% of its original weight by day 18 (lockdown). Too little or too much weight loss can indicate humidity issues:

• Too little weight loss = humidity too high → small air cell → chick may drown
• Too much weight loss = humidity too low → large air cell → chick may be weak or stuck

🧪 How to Monitor Egg Weight Loss

1. Weigh eggs before setting (Day 0)
2. Weigh weekly (Day 7, 14, and 18) — or more often if needed
3. Calculate percentage loss:
   • Weight loss % = ((Start weight – Current weight) ÷ Start weight) × 100

4. Adjust humidity based on results

💡 Quick Tips:

• Use a precision digital scale for best accuracy
• Track each egg or an average of several for batch hatching

Candle to monitor air cell size as a visual reference