Paediatric Maintenance Fluid Calculator
Paediatric Maintenance Fluid Calculator
Routine maintenance intravenous fluid volume in a child by the Holliday-Segar method, in the form NICE NG29 states it — with the hourly 4-2-1 equivalent, and the reason maintenance fluid in children is now isotonic rather than hypotonic.
Holliday-Segar maintenance fluid volume
Weight → mL/dayA 14 kg child, full routine maintenance
The Holliday-Segar method, as NICE NG29 states it
next 10 kg (10 to 20 kg): 50 mL/kg/day
each kg above 20 kg: 20 mL/kg/day
hourly rate = daily volume ÷ 24
- 100 / 50 / 20
- the three tiers, quoted verbatim in NICE NG29 recommendation 1.4.1. They approximate energy expenditure per kilogram, which falls as a child grows, and water requirement tracks energy expenditure at roughly 1 mL per kcal
- the 4-2-1 rule
- the same three tiers divided by 24, rounded for bedside use. 100 ÷ 24 is 4.17, 50 ÷ 24 is 2.08 and 20 ÷ 24 is 0.83 — so 4-2-1 slightly under-reads the first two tiers and over-reads the third by about 20%. For a child under 20 kg the two methods agree to within a few per cent; for a large adolescent 4-2-1 gives the higher number
- 10 kg and 20 kg
- the breakpoints. A 10 kg child gets 1,000 mL/day, a 20 kg child 1,500 mL/day, and the function is continuous at both — there is no jump
- what it does not include
- deficit, ongoing losses, resuscitation fluid, and the extra insensible losses of fever, tachypnoea or phototherapy. Holliday-Segar estimates maintenance and only maintenance
- the composition
- the formula gives a volume, not a fluid. NICE NG29 1.4.3 sets the composition: isotonic crystalloid with sodium 131 to 154 mmol/litre. Volume and tonicity are separate decisions and the tonicity is the one that caused harm
- the 50-80% range
- NICE NG29 1.4.9, for a risk of water retention from non-osmotic ADH secretion. It is a range the guideline names, not a sliding scale — and restriction does not remove the need to measure the sodium
Worked example
A 14 kg child, full routine maintenance
First 10 kg at 100 mL/kg/day = 1,000 mL/day
Remaining 4 kg at 50 mL/kg/day = 200 mL/day
Total = 1,000 + 200 = 1,200 mL/day
Hourly rate = 1,200 ÷ 24 = 50 mL/hour
By the 4-2-1 rule: (4 × 10) + (2 × 4) = 40 + 8 = 48 mL/hour. The two differ by 2 mL/hour, or 4%, because 4-2-1 rounds 4.17 down to 4 and 2.08 down to 2
At 80% restriction the same child gets 1,200 × 0.8 = 960 mL/day, or 40 mL/hour
A 25 kg child gets 1,000 + 500 + (5 × 20) = 1,600 mL/day; a 70 kg adolescent gets 1,000 + 500 + (50 × 20) = 2,500 mL/day, which is well above NICE CG174's adult 25-30 mL/kg/day of 1,750-2,100 mL — the point at which the formula should stop being extrapolated
Maintenance volume and hourly rate by weight, full maintenance
| Weight | Daily volume (mL/day) | Hourly rate (mL/hour) | 4-2-1 hourly rate |
|---|---|---|---|
| 3 kg | 300 | 12.5 | 12 |
| 5 kg | 500 | 20.8 | 20 |
| 10 kg | 1,000 | 41.7 | 40 |
| 14 kg | 1,200 | 50.0 | 48 |
| 20 kg | 1,500 | 62.5 | 60 |
| 25 kg | 1,600 | 66.7 | 65 |
| 40 kg | 1,900 | 79.2 | 80 |
| 60 kg | 2,300 | 95.8 | 100 |
What the volume does and does not cover
| Fluid need | Included in this number? |
|---|---|
| Routine maintenance water | Yes — that is what Holliday-Segar estimates |
| Existing dehydration deficit | No. Calculate the deficit from weight loss or clinical assessment and add it separately |
| Ongoing losses — vomiting, diarrhoea, stoma, drain, nasogastric aspirate | No. Replace these millilitre for millilitre with a fluid of appropriate composition |
| Resuscitation fluid for shock | No. That is a separate bolus prescription |
| Extra insensible loss from fever, tachypnoea, radiant heater or phototherapy | No |
| The tonicity and glucose content of the fluid | No. The formula gives a volume only; NICE NG29 1.4.3 and 1.4.7 set the composition |
| Enteral intake already being given | No. Subtract it, or the child is given both and ends up fluid-overloaded |
Why maintenance fluid in children is isotonic now
| Point in time | What changed |
|---|---|
| Holliday and Segar, 1957 | Published the 100/50/20 volumes, derived from energy expenditure. The paper is about volume, not tonicity |
| Decades of practice | Hypotonic maintenance fluid, typically sodium chloride 0.18% with glucose 4%, became standard in children and is still taught in older textbooks |
| NPSA Patient Safety Alert 22, 2007 | Reducing the risk of hyponatraemia when administering intravenous infusions to children. Sodium chloride 0.18% with glucose 4% restricted to specialist units after deaths and neurological injury from hospital-acquired hyponatraemia |
| NICE NG29, 2015 | Recommendation 1.4.3: initially use isotonic crystalloids containing sodium 131 to 154 mmol/litre for routine maintenance. Recommendation 1.4.4: measure plasma electrolytes and blood glucose at the start and at least every 24 hours |
| Now | Isotonic is standard for routine maintenance in children. Hypotonic fluid has specific indications, prescribed deliberately and monitored, not as a default |
A 1957 volume, and the tonicity that took fifty years to fix
Holliday and Segar’s 1957 paper did something simple and durable: it tied water requirement to energy expenditure, observed that energy expenditure per kilogram falls as a child grows, and produced three tiers — 100 mL/kg/day for the first ten kilograms, 50 for the next ten, 20 for everything above twenty. Nearly seventy years later NICE still states the method in those exact figures, and the bedside 4-2-1 rule is nothing more than the same tiers divided by twenty-four and rounded for mental arithmetic. The rounding is not free: 100 over 24 is 4.17 and 20 over 24 is 0.83, so 4-2-1 reads slightly low in a small child and about a fifth high in the top tier. For a toddler the difference is a few millilitres an hour and nobody cares; for a sixty-kilogram adolescent it is five millilitres an hour, and by then the whole extrapolation deserves more scrutiny than the rounding does.
What the formula estimates is maintenance, and only maintenance — the water a child needs to replace obligatory urinary and insensible losses while nothing else is going on. It contains no deficit. It contains no allowance for vomiting, diarrhoea, a stoma, a surgical drain or nasogastric aspirate. It makes no adjustment for fever, for tachypnoea, for a radiant heater or for phototherapy, all of which increase insensible loss. And it takes no account of what the child is already receiving enterally, which is the omission that most often produces an overfilled child rather than an underfilled one. In practice the maintenance number is frequently the smaller part of a day’s fluid prescription, and treating it as the whole answer is the commonest way the calculation goes wrong.
The more important point is that the formula gives a volume and says nothing about the fluid. For decades the fluid used was hypotonic — sodium chloride 0.18% with glucose 4% in the United Kingdom — and that combination caused harm. An acutely unwell child secretes antidiuretic hormone for non-osmotic reasons: pain, nausea, vomiting, surgery, pneumonia, bronchiolitis, meningitis. Unable to excrete free water, and given a fluid that is mostly free water at maintenance rate, the plasma sodium falls. Acute hyponatraemia in a child is not a laboratory curiosity; it causes seizures, cerebral oedema, permanent neurological injury and death. The National Patient Safety Agency issued Patient Safety Alert 22 in 2007 and restricted the 0.18% solution to specialist units, and NICE NG29 now recommends that routine maintenance in children and young people begin with an isotonic crystalloid containing sodium in the range 131 to 154 mmol/litre. Term neonates are handled separately, with professional judgement in the first week and isotonic crystalloid with 5 to 10% glucose from day eight.
Two habits follow from that history. The first is monitoring: NICE asks for plasma electrolytes and blood glucose when intravenous fluids are started and at least every twenty-four hours thereafter, which exists precisely because the failure mode is biochemical and silent until it is not. The second is restriction. Where the risk of non-osmotic antidiuretic hormone secretion is high, the guideline offers 50% to 80% of routine maintenance — and a restricted volume makes the sodium more worth measuring, not less. Neither habit is optional, and neither is something a calculator can do. The volume above is a starting point that a clinician then adjusts for the deficit, the losses, the enteral intake and the sodium, which is the whole of the actual work.
Frequently asked questions
What is the Holliday-Segar formula for maintenance fluids in children?
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 kg. NICE NG29 recommendation 1.4.1 states it in those figures. A 14 kg child therefore needs 1,000 + 200 = 1,200 mL/day.
Is the 4-2-1 rule the same as Holliday-Segar?
It is the same tiers divided by 24 and rounded: 4 mL/kg/hour for the first 10 kg, 2 for the next 10 and 1 for each kg above 20. The exact divisions are 4.17, 2.08 and 0.83, so 4-2-1 reads a little low in small children and about 20% high in the top tier. Below about 30 kg the two agree to within a few per cent.
Should maintenance fluid in children be isotonic or hypotonic?
Isotonic. NICE NG29 recommendation 1.4.3 is to initially use isotonic crystalloids containing sodium in the range 131 to 154 mmol/litre for routine maintenance. Hypotonic maintenance fluid caused hospital-acquired hyponatraemia, and NPSA Patient Safety Alert 22 in 2007 restricted sodium chloride 0.18% with glucose 4% to specialist units. Older textbooks that teach the hypotonic regimen are out of date.
Does Holliday-Segar include the fluid deficit?
No. It estimates maintenance only. A dehydration deficit, ongoing losses from vomiting, diarrhoea, a stoma or a drain, resuscitation boluses and the extra insensible losses of fever or phototherapy are all calculated and added separately. Enteral intake should be subtracted.
When should maintenance fluid be restricted in a child?
NICE NG29 recommendation 1.4.9 says to consider restricting to 50% to 80% of routine maintenance where there is a risk of water retention from non-osmotic antidiuretic hormone secretion — which covers many acutely unwell children, the perioperative period, meningitis, bronchiolitis and pneumonia. Plasma sodium must still be measured at the start and at least daily.
Does this formula work for neonates?
Not straightforwardly. Holliday-Segar was derived for children, and NICE NG29 deals with term neonates separately: professional judgement for the first 7 days, then isotonic crystalloid containing sodium 131 to 154 mmol/litre with 5 to 10% glucose from day 8. A glucose-free fluid at maintenance rate does not meet a neonate’s glucose requirement of 4 to 6 mg/kg/min.
Related calculators
References
- National Institute for Health and Care Excellence. Intravenous Fluid Therapy in Children and Young People in Hospital. NICE guideline NG29. London: NICE; 2015, updated 2020 — recommendations 1.4.1 (Holliday-Segar volumes), 1.4.3 (isotonic crystalloids, sodium 131–154 mmol/litre), 1.4.4 (electrolyte and glucose monitoring), 1.4.7 (term neonates) and 1.4.9 (restriction to 50–80%).
- Holliday MA, Segar WE. The maintenance need for water in parenteral fluid therapy. Pediatrics. 1957;19(5):823–832.
- National Patient Safety Agency. Patient Safety Alert 22: Reducing the Risk of Hyponatraemia When Administering Intravenous Infusions to Children. London: NPSA; 2007.
- National Institute for Health and Care Excellence. Intravenous Fluid Therapy in Adults in Hospital. NICE clinical guideline CG174. London: NICE; 2013, updated 2017 — recommendation 1.4.1, routine maintenance 25–30 mL/kg/day of water.
Medical Disclaimer: The tools and content provided here are for educational and reference purposes only. They are not intended to substitute for professional medical advice, diagnosis, or treatment. Clinical decisions should always be based on the comprehensive assessment of a qualified healthcare professional.