You can tell if you are dehydrated by observing several signs and symptoms that range from mild to severe. Common indicators of mild to moderate dehydration include:

• Feeling thirsty
• Dry or sticky mouth
• Not urinating much or urinating less often than usual
• Dark yellow or amber-colored urine
• Dry, cool skin
• Headache
• Muscle cramps
• Feeling dizzy or lightheaded
• Fatigue or tiredness
• Dry lips and tongue
• Sunken eyes (in more significant dehydration)

Severe dehydration signs are more serious and require immediate medical attention. These include:

• Very dark or no urine output
• Dry, shriveled skin that does not bounce back quickly when pinched (poor skin turgor)
• Rapid heartbeat and rapid breathing
• Confusion, irritability, or unconsciousness
• Sunken eyes
• Dizziness or fainting
• Shock due to insufficient blood flow

For babies and young children, signs include sunken soft spot on the head, fewer wet diapers, no tears when crying, and irritability or drowsiness

. A practical way to check dehydration is to look at your urine color: pale yellow indicates good hydration, while darker urine suggests dehydration

. Also, pinching the skin on the back of your hand and seeing if it returns to normal quickly can indicate hydration status; slow return or "tenting" suggests dehydration

. If you experience symptoms like extreme thirst, dizziness, rapid heartbeat, confusion, or very dark urine, seek medical care promptly as these indicate severe dehydration

. In summary, monitor thirst, urine color and frequency, skin condition, and symptoms like headache, dizziness, and fatigue to know if you are dehydrated. Severe signs require urgent medical attention.