What is the maintenance fluid rate?
Enter a body weight to calculate the maintenance fluid volume per day by the Holliday-Segar method and the hourly rate by the 4-2-1 rule. For information only. This is not medical advice or a diagnosis. Do not use it to make treatment decisions without a clinician. No licensed clinician has reviewed this page.
- Per day (Holliday-Segar)
- 1,250
The maintenance fluid is 1,250 mL per day, or 50 mL per hour by the 4-2-1 rule.
- Per hour (daily ÷ 24)
- 52.1
- Per hour (4-2-1 rule)
- 50
Per day (Holliday-Segar): 1,250. The maintenance fluid is 1,250 mL per day, or 50 mL per hour by the 4-2-1 rule.
This calculator gives general information only. It is not medical advice and does not replace a doctor or other health care provider. Talk with a professional about your results. Terms of use
How to calculate
Calculates the maintenance fluid volume per day by the Holliday-Segar method and the hourly rate by the 4-2-1 rule from body weight.
Example with the default inputs (Weight 33.0693393277316 lb): The maintenance fluid is 1,250 mL per day, or 50 mL per hour by the 4-2-1 rule.
Method: Per day: 100 mL/kg for the first 10 kg + 50 mL/kg for 10 to 20 kg + 20 mL/kg above 20 kg. Per hour (4-2-1): 4 mL/kg + 2 mL/kg + 1 mL/kg over the same bands.
- The Holliday-Segar method estimates water needs from calories burned; it gives a volume, not a fluid type.
- Newborns in the first weeks of life and people with kidney, heart, or hormone disorders need other rules.
- The daily volume is rounded to a whole mL and each hourly rate to 1 decimal, halves up.
Worked examples
Each example is checked against the calculator on every build.
- Weight 17.64 lb gives Per day (Holliday-Segar) 800, Per hour (daily ÷ 24) 33.3, Per hour (4-2-1 rule) 32.Source: Holliday and Segar 1957: 100 × 8 = 800 mL/day
- Weight 33.07 lb gives Per day (Holliday-Segar) 1,250, Per hour (daily ÷ 24) 52.1, Per hour (4-2-1 rule) 50.
- Weight 66.14 lb gives Per day (Holliday-Segar) 1,700, Per hour (daily ÷ 24) 70.8, Per hour (4-2-1 rule) 70.
- Weight 154.3 lb gives Per day (Holliday-Segar) 2,500, Per hour (daily ÷ 24) 104.2, Per hour (4-2-1 rule) 110.
- Weight 20 lb gives Per day (Holliday-Segar) 907, Per hour (daily ÷ 24) 37.8, Per hour (4-2-1 rule) 36.3.
Medical disclaimer
This calculator is for information and education only. It is not medical advice, and its result is not a diagnosis. Do not use it to start, stop, or change a treatment without a clinician who knows your health history. No licensed clinician has reviewed this page. This site's editors checked the formulas and worked examples against published sources. If you think you have a medical emergency, call your local emergency number.
When this does not apply. Holliday and Segar (1957) wrote the rule for children. It does not apply to newborns younger than 28 days, or to people with heart, kidney, or liver disease, severe burns, large fluid losses, or a hormone disorder that changes water balance (Feld 2018 leaves out the same groups). The result is not a prescription: a clinician sets the fluid, the rate, and any upper limit.
How the fluid is worked out
With the weight W in kilograms (pounds × 0.45359237):
- Per day (Holliday-Segar): 100 mL × (the first 10 kg) + 50 mL × (the next 10 kg) + 20 mL × (each kg above 20). In one line: 100 × min(W, 10) + 50 × min(max(W − 10, 0), 10) + 20 × max(W − 20, 0).
- Per hour (daily ÷ 24): the daily volume divided by 24.
- Per hour (4-2-1 rule): 4 × min(W, 10) + 2 × min(max(W − 10, 0), 10) + 1 × max(W − 20, 0).
The daily volume is rounded to a whole mL, and each hourly rate to 1 decimal place, halves up, read from the decimal value (within 1e-9, relative, of a half counts as the half). The rates are worked out from the unrounded weight. No upper limit is applied.
Inputs the calculator accepts
Weight 3 to 150 kg.
Worked examples by hand
8 kg. 100 × 8 = 800 mL/day; 800 ÷ 24 = 33.3 mL/h; 4-2-1: 4 × 8 = 32.0 mL/h.
15 kg. 1,000 + 50 × 5 = 1,250 mL/day; ÷ 24 = 52.1 mL/h; 4-2-1: 40 + 2 × 5 = 50.0 mL/h.
30 kg. 1,000 + 500 + 20 × 10 = 1,700 mL/day; ÷ 24 = 70.8 mL/h; 4-2-1: 40 + 20 + 10 = 70.0 mL/h.
70 kg. 1,500 + 20 × 50 = 2,500 mL/day; ÷ 24 = 104.2 mL/h; 4-2-1: 60 + 50 = 110.0 mL/h.
20 lb (9.0718 kg). 100 × 9.0718 = 907.18 = 907 mL/day; ÷ 24 = 37.8 mL/h; 4-2-1: 4 × 9.0718 = 36.3 mL/h.
Other questions people ask
What is the Holliday-Segar method?
Holliday and Segar (1957) linked water needs to the calories a child burns. Their rule: 100 mL per kg per day for the first 10 kg of body weight, 50 mL per kg for the next 10 kg, and 20 mL per kg for each kg above 20. A 15 kg child gets 1,000 + 250 = 1,250 mL a day.
What is the 4-2-1 rule?
The hourly form of the same idea: 4 mL per kg per hour for the first 10 kg, 2 mL per kg for the next 10 kg, and 1 mL per kg above 20 kg. For weights over 20 kg this is 60 mL/h plus 1 mL/h per kg above 20. It is slightly different from the daily volume divided by 24, and the page shows both.
Does the calculator say which fluid to give?
No. It gives a volume only. The 2018 American Academy of Pediatrics guideline recommends isotonic fluids for most children who need maintenance IV fluids, but the choice of fluid and rate is a clinical decision.
Who is this rule not for?
Newborns in the first weeks of life, and anyone with kidney disease, heart failure, severe burns, or a hormone disorder that changes water balance. Their clinicians use other methods.