Fluid Requirement Calculator
Holliday-Segar routine maintenance fluid for children, in mL per day and per hour, with the daily ceilings and neonatal rates NICE sets alongside it.
Fluid Requirement Calculator: with the default inputs, routine maintenance per 24 hours is 1,500 mL.
A weight measured today, in kilograms.
Only used to pick which of NICE's two daily ceilings to flag against.
- Rate in mL per hour
- 62.5
- From the first 10 kg, at 100 mL/kg/day
- 1,000 mL
- From the next 10 kg, at 50 mL/kg/day
- 500 mL
- From the weight over 20 kg, at 20 mL/kg/day
- 0 mL
- Effective mL per kg per day
- 75
- Against the daily figure NICE says is rarely exceeded
- Within the 2,500 mL that NICE says males rarely exceed over 24 hours
Assumptions
- This is an estimate for education. It does not diagnose anything and does not replace clinical judgement. It is not a prescribing tool.
- Rates are the Holliday-Segar figures as stated in NICE NG29: 100 mL/kg/day for the first 10 kg, 50 for the next 10 kg and 20 for the weight above 20 kg.
- This is routine maintenance only. Resuscitation fluid, deficit replacement, ongoing losses and redistribution are separate and additional.
- The 2,500 mL and 2,000 mL figures are NICE's note that males and females respectively rarely need more than that over 24 hours; the calculator flags them rather than capping.
- Holliday-Segar does not apply to term neonates in the first days of life, for whom NICE gives age-based rates, or to preterm infants.
- The formula assumes a well child at rest; fever, tachypnoea, phototherapy and ambient heat raise requirements, while humidified ventilation and renal or cardiac impairment lower them.
- mL/day1,000100%
| Weight (kg) | mL per day | mL per hour | mL/kg/day | |
|---|---|---|---|---|
| 5 | 500 | 20.8 | 100 | |
| 10 | 1,000 | 41.7 | 100 | |
| 15 | 1,250 | 52.1 | 83 | |
| 20 | 1,500 | 62.5 | 75 | ← nearest |
| 30 | 1,700 | 70.8 | 57 | |
| 40 | 1,900 | 79.2 | 48 | |
| 60 | 2,300 | 95.8 | 38 | |
| 70 | 2,500 | 104.2 | 36 |
The hourly column is where the bedside "4-2-1 rule" comes from: 100, 50 and 20 mL/kg/day divided by 24 are 4.17, 2.08 and 0.83 mL/kg/hour, rounded to 4, 2 and 1.
| Age | Routine maintenance |
|---|---|
| Birth to day 1 | 50 to 60 mL/kg/day |
| Day 2 | 70 to 80 mL/kg/day |
| Day 3 | 80 to 100 mL/kg/day |
| Day 4 | 100 to 120 mL/kg/day |
| Days 5 to 28 | 120 to 150 mL/kg/day |
NICE NG29 recommendation 1.4.2, for term neonates needing intravenous fluids for routine maintenance. Preterm infants need specialist input.
How this is worked out
The formula
Holliday-Segar routine maintenance, per 24 hours: first 10 kg of body weight 100 mL/kg/day next 10 kg (10 to 20 kg) 50 mL/kg/day every kg above 20 kg 20 mL/kg/day Hourly rate = daily volume ÷ 24 (the bedside 4-2-1 rule is these three figures divided by 24 and rounded) NICE notes that over 24 hours males rarely need more than 2,500 mL and females rarely more than 2,000 mL.
Open How it’s calculated above to see this worked through with your own numbers.
What you enter
- Weight
- A weight measured today, in kilograms.in kg, lb · from 0 to 150 · defaults to 20
- Sex
- Only used to pick which of NICE's two daily ceilings to flag against.Male — NICE notes 2,500 mL/day is rarely exceeded · Female — NICE notes 2,000 mL/day is rarely exceeded
- Percentage of routine maintenance(under More options)
- NICE suggests restricting to 50% to 80% of routine maintenance where there is a risk of hypervolaemia. Leave at 100 for the full rate.a percentage · from 0 to 150 · defaults to 100
What you get back
- Routine maintenance per 24 hoursmain answer
- Rate in mL per hour
- From the first 10 kg, at 100 mL/kg/day
- From the next 10 kg, at 50 mL/kg/day
- From the weight over 20 kg, at 20 mL/kg/day
- Effective mL per kg per day
- Against the daily figure NICE says is rarely exceeded
What this assumes
- This is an estimate for education. It does not diagnose anything and does not replace clinical judgement. It is not a prescribing tool.
- Rates are the Holliday-Segar figures as stated in NICE NG29: 100 mL/kg/day for the first 10 kg, 50 for the next 10 kg and 20 for the weight above 20 kg.
- This is routine maintenance only. Resuscitation fluid, deficit replacement, ongoing losses and redistribution are separate and additional.
- The 2,500 mL and 2,000 mL figures are NICE's note that males and females respectively rarely need more than that over 24 hours; the calculator flags them rather than capping.
- Holliday-Segar does not apply to term neonates in the first days of life, for whom NICE gives age-based rates, or to preterm infants.
- The formula assumes a well child at rest; fever, tachypnoea, phototherapy and ambient heat raise requirements, while humidified ventilation and renal or cardiac impairment lower them.
About this calculator
This is an estimate for education. It does not diagnose anything and does not replace clinical judgement. It is not a prescribing tool.
A note on what this page is. The brief for this calculator was body-surface-area dosing. That turned out not to be a distinct tool: the site's body surface area calculator already computes BSA by four formulas and multiplies it by a dose in mg/m², which is the whole of BSA dosing. Rather than ship a duplicate under a second name, this is Holliday-Segar maintenance fluid instead — genuinely different arithmetic, and the paediatric calculation people most often need.
What the formula is
Holliday and Segar published it in Pediatrics in 1957. It is a stepped rule, so that the millilitres per kilogram fall as body size rises — 100 mL/kg/day at 10 kg works out at 64 mL/kg/day by 25 kg and 36 by 70 kg. Every paediatric service uses it:
- 100 mL/kg/day for the first 10 kg
- 50 mL/kg/day for the next 10 kg
- 20 mL/kg/day for every kilogram above 20
NICE NG29 recommends it by name for calculating routine maintenance intravenous fluid rates in children and young people, and states the three figures in exactly those terms.
A 25 kg child therefore needs (10 × 100) + (10 × 50) + (5 × 20) = 1,600 mL a day, or about 67 mL an hour.
The 4-2-1 rule
Divide those three rates by 24 and you get 4.17, 2.08 and 0.83 mL/kg/hour, which round to 4, 2 and 1. That is the whole derivation of the bedside rule used in anaesthesia. The rounding is not in one direction: 4 and 2 round down while 1 rounds up, so 4-2-1 runs slightly below Holliday-Segar up to about 35 kg and slightly above it beyond. For a few hours of theatre the difference is immaterial; over a day it is not.
The ceilings
NICE adds a caution alongside the formula: over a 24-hour period, males rarely need more than 2,500 mL and females rarely more than 2,000 mL. The formula keeps scaling with weight; adult requirements do not. This calculator flags when the arithmetic goes above the relevant figure.
There is a restriction field under More options as well, because NICE suggests restricting to 50% to 80% of routine maintenance in children who are hypervolaemic or at risk of it — for instance where increased ADH secretion is likely.
Neonates are different
Holliday-Segar does not apply in the first days of life. NICE gives routine maintenance for term neonates by day of age instead: 50-60 mL/kg/day from birth to day 1, 70-80 on day 2, 80-100 on day 3, 100-120 on day 4, and 120-150 from day 5 to day 28. Those are in the second table below. Preterm infants need specialist input.
What this number is not
It is maintenance only. Resuscitation fluid, replacement of an existing deficit, ongoing losses from vomiting, diarrhoea, drains, stoma or burns, and redistribution in conditions such as sepsis are all separate prescriptions on top of it.
And the composition matters as much as the volume. NICE recommends isotonic crystalloids containing sodium in the range 131 to 154 mmol/L for routine maintenance, with plasma electrolytes and blood glucose measured when fluids start and at least every 24 hours after. The sodium content and the monitoring are as much a part of the prescription as the volume, and getting the volume right does not make the fluid safe on its own.
Frequently asked questions
▸What is the Holliday-Segar formula?
100 mL/kg/day for the first 10 kg of body weight, 50 mL/kg/day for the next 10 kg, and 20 mL/kg/day for every kilogram above 20. NICE recommends it by name for routine maintenance intravenous fluids in children.
▸How does the 4-2-1 rule relate to it?
It is the same formula per hour, rounded: 100, 50 and 20 mL/kg/day divided by 24 are 4.17, 2.08 and 0.83 mL/kg/hour. Because 4 and 2 round down while 1 rounds up, 4-2-1 runs slightly below Holliday-Segar up to about 35 kg and slightly above it beyond.
▸Is there a maximum daily volume?
NICE notes that over 24 hours males rarely need more than 2,500 mL and females rarely more than 2,000 mL. The formula keeps scaling with weight past the point where adult requirements stop.
▸Does this apply to newborns?
No. NICE gives routine maintenance for term neonates by day of age — 50 to 60 mL/kg/day from birth to day 1, rising to 120 to 150 mL/kg/day from day 5. Preterm infants need specialist input.
▸Does maintenance fluid include replacing losses?
No. Resuscitation fluid, existing deficits, ongoing losses and redistribution are all prescribed separately and in addition.
Put this calculator on your own site
A working maintenance fluid, free for any site, with no ads and no sign-up. It resizes to fit wherever you paste it and updates itself as this page improves.
Paste this anywhere. It works on any site, carries no ads, never expires, and always shows the current version.
Fluid Requirement Calculator by CalculateItNow
The page's own title. The clearest description of what the link leads to.
The credit line sits outside the widget on purpose, so it is a real link on your page rather than one buried in a frame. Please keep it — it is what pays for CalculateItNow staying free and ad-free. The script only resizes the widget to fit its contents; drop it and the widget still works.
Browse every calculator widget·How to add it to WordPress, Squarespace or Wix
Related calculators
The questions people ask next to a maintenance fluid.
Weight-based mg/kg dosing arithmetic with per-dose and daily ceilings. It supplies the arithmetic only — every number in it must come from approved labelling.
The five Apgar signs scored 0 to 2, using the AAP and ACOG descriptors, with what each total does and does not mean for a newborn.
Estimate how much water to drink a day from body weight, exercise and climate, compared with the NASEM adequate intake — and an honest take on the '8 glasses' rule.
Calculate body surface area in m² by the Du Bois, Mosteller, Haycock and Gehan formulas at once, with the drug dose that BSA implies.