Child’s Daily Fluid Need
The Holliday–Segar method: 100 mL per kilogram for the first 10 kg, 50 mL for the next 10, and 20 mL for every kilogram above 20. An 18 kg child needs 1,000 + 400 = 1,400 mL.
Your numbers
Daily fluid need
1,400mL
Fluid per kg
77.8mL
Fluid an hour
58.3mL
Formula
Daily fluid need = 100 × 10 + 50 × 10 + 20 × (Weight (kg) − 20)
That total includes water inside food. Fever and diarrhoea raise the requirement — see a clinician in those cases.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Weight (kg) (kg)The second weight you are comparing against. | 18 | 1 ~ 80 |
Step by step
Quick reference table
Results when only Weight (kg) (kg) changes and everything else stays put.
| Weight (kg) (kg) | Daily fluid need (mL) | Fluid per kg (mL) | Fluid an hour (mL) |
|---|---|---|---|
| 9 | 900 | 100 | 37.5 |
| 13.5 | 1,175 | 87 | 49 |
| 18 | 1,400 | 77.8 | 58.3 |
| 27 | 1,640 | 60.7 | 68.3 |
| 36 | 1,820 | 50.6 | 75.8 |
What each result means
| Result | At default values |
|---|---|
| Daily fluid need (mL)A child’s daily fluid need, water in food included. | 1,400 |
| Fluid per kg (mL)Fluid needed per kilogram; smaller children need more. | 77.8 |
| Fluid an hour (mL)The daily need spread across 24 hours. | 58.3 |
Common mistakes
That total includes water inside food. Fever and diarrhoea raise the requirement — see a clinician in those cases.
Glossary
- Weight (kg)
- The second weight you are comparing against.
- Daily fluid need
- A child’s daily fluid need, water in food included.
- Fluid per kg
- Fluid needed per kilogram; smaller children need more.
- Fluid an hour
- The daily need spread across 24 hours.
Frequently asked questions
Q. How is Child’s Daily Fluid Need calculated?
Daily fluid need = 100 × 10 + 50 × 10 + 20 × (Weight (kg) − 20) — The Holliday–Segar method: 100 mL per kilogram for the first 10 kg, 50 mL for the next 10, and 20 mL for every kilogram above 20. An 18 kg child needs 1,000 + 400 = 1,400 mL.
Q. Can you walk through an example?
With Weight (kg) 18kg, the answer is Daily fluid need 1,400mL.
Q. What do I need to enter?
Enter Weight (kg). The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Weight (kg) (kg) moves the answer to Weight (kg) (kg) 9 → Daily fluid need (mL) 900 and Weight (kg) (kg) 36 → Daily fluid need (mL) 1,820. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
That total includes water inside food. Fever and diarrhoea raise the requirement — see a clinician in those cases.
Related calculators
These calculators help you understand health figures; they do not replace diagnosis or prescription. See a clinician if you have symptoms.