Health Education Tool

Child Fluid Requirement Calculator

Estimate a child's maintenance fluid requirements, assess hydration during illness, and learn when medical advice may be needed. This educational tool does not diagnose dehydration.

1
Basic Info
2
Illness & Symptoms
3
Hydration
Step 1 of 3 — Basic Information
Basic Information
Used to calculate age and age-specific guidance.
Enter current weight in kilograms. Weight is used to estimate maintenance fluid requirements.
Important Safety Note: If a child appears severely unwell, has difficulty breathing, is difficult to wake, or you are seriously concerned — seek urgent medical care immediately, regardless of this tool's result.
Estimated Maintenance Fluid Requirement
This estimate is based on the child's weight using a commonly used maintenance fluid formula. Actual fluid needs may differ depending on illness, activity level and environmental conditions.
PeriodVolume
The child does not need to drink exactly this amount every hour. Small frequent drinks are often easier to tolerate. The goal is to achieve the total fluid requirement over time.
Hydration Assessment
Suggested Next Steps
Seek Medical Advice Promptly If The Child Has:
  • Very little urine output
  • Refusing fluids
  • Repeated vomiting
  • Most fluids being vomited back
  • Marked lethargy
  • Dry mouth
  • No tears when crying
  • Worsening illness
Values Entered
This calculator provides educational information only. It does not diagnose dehydration, prescribe treatment, or replace assessment by a qualified healthcare professional. Always seek medical advice if you are concerned about a child's condition.

Understanding Fluid Needs in Children

Educational information about maintenance fluid requirements, dehydration signs, and when to seek medical advice.

What Is Maintenance Fluid Requirement?

Maintenance fluid requirement is an estimate of the amount of fluid normally needed to maintain hydration. It accounts for fluid lost through normal body processes such as breathing, sweating, and urine production. This estimate can guide how much a child should drink each day under typical conditions.

Why Is Weight Important?

Children's fluid requirements depend largely on body weight. Heavier children generally require more fluid. The commonly used maintenance fluid formula provides an estimate based on the child's current weight, which is why an accurate weight measurement is helpful when using this calculator.

Why Can Illness Increase Fluid Needs?

Fever, vomiting and diarrhoea may increase fluid losses. A child with fever loses additional fluid through sweating and increased respiratory rate. Vomiting and diarrhoea can cause significant additional fluid losses depending on their frequency and severity. Some children may require more fluid than the maintenance estimate shown by this calculator.

Why Is Urine Output Important?

Reduced urine output may be an early sign of dehydration. When a child is not getting enough fluid, the body conserves water by producing less urine. Monitoring urine output can help identify children who may need medical assessment. If a child has not passed urine for several hours, this may indicate dehydration.

What Are Signs Of Dehydration?

Common signs of dehydration in children include: dry mouth or tongue, reduced urine output, absence of tears when crying, lethargy or reduced activity, and reduced willingness to drink. More serious dehydration may cause sunken eyes, skin that does not spring back quickly when pinched, and marked lethargy. These findings require prompt medical assessment.

Should Children Drink Constantly?

Not necessarily. The goal is to achieve an adequate total fluid intake over the course of the day. Many children tolerate small frequent drinks better than large volumes at once, particularly when they are unwell or vomiting. Offering small amounts regularly is often more effective than encouraging large single amounts of fluid.

What If My Child Keeps Vomiting?

Offer small amounts frequently. Waiting a few minutes after a vomiting episode before offering fluids again can sometimes help. Offering a teaspoon or two at a time, gradually increasing the amount as tolerated, is often better than offering a large drink at once. If most or all fluids are repeatedly vomited back, medical assessment is recommended.

When Should Medical Advice Be Sought?

Medical advice should be sought if dehydration is suspected, symptoms worsen, or warning signs are present. Young infants under 3 months should be assessed promptly with any illness. A child who is refusing all fluids, has no urine output, has persistent vomiting, or appears significantly unwell should be seen by a healthcare professional without delay.

Frequently Asked Questions

The calculator uses a commonly used weight-based maintenance fluid formula. For children up to 10 kg, the estimate is 100 mL per kg per day. For children between 10 and 20 kg, an additional 50 mL per kg per day is added for each kg above 10. For children above 20 kg, a further 20 mL per kg per day is added for each kg above 20.

Yes. Fever may increase fluid losses and fluid requirements. Children with fever lose additional fluid through sweating and faster breathing. The calculator provides a baseline maintenance estimate; actual requirements may be higher when a child has a fever.

Yes. Loose stools can increase fluid loss and may require additional oral fluids. The amount of extra fluid needed depends on the frequency and volume of loose stools. This calculator provides age-specific guidance on additional fluids that may be offered after each loose stool.

Offer small amounts more frequently. Waiting a short time after a vomiting episode before offering fluids again may help. Giving a teaspoon or small sip at a time, gradually increasing as tolerated, is often better than offering a large drink. If most fluids are repeatedly vomited back, seek medical advice.

No. It provides educational guidance only. The hydration assessment in this tool is based on a simple scoring system and cannot replace clinical assessment by a healthcare professional. If you are concerned about dehydration, seek medical advice.

Dr. Seneth Gajasinghe

MBBS (Col), MD (Col)

SLMC No. 27329

Medical reviewer & author
Sineth Hospitals, Sri Lanka

Sineth Hospitals

Rattanapitiya, Boralasgamuwa, Sri Lanka
0 727 725 725  |  info@sinethhospitals.com

Disclaimer: This tool is intended for educational purposes only and does not constitute medical advice, diagnosis, or treatment. It cannot diagnose dehydration or replace clinical assessment by a qualified healthcare professional. Do not make clinical decisions based solely on the output of this tool. If you are concerned about a child's condition, seek medical advice promptly.