Is this the same formula as MDCalc maintenance fluids?

Yes — MDCalc maintenance fluids and this page both use the Holliday-Segar 4-2-1 rule: 4 mL/kg/hr for the first 10 kg, +2 mL/kg/hr for kg 11–20, +1 mL/kg/hr for each kg above 20. Daily volume = hourly × 24 (or 100/50/20 mL/kg/day tiers). Breakpoints: 10 kg → 40 mL/hr, 20 kg → 60 mL/hr, 25 kg → 65 mL/hr. Tables above match that bedside arithmetic. Education only — not affiliated with MDCalc.

How do you calculate maintenance IV fluids (4-2-1 rule)?

Holliday-Segar (4-2-1) gives hourly mL/hr: 4 mL/kg/hr for the first 10 kg, +2 mL/kg/hr for kg 11–20, +1 mL/kg/hr for each kg >20. Daily volume = hourly × 24, or use daily equivalents 100 / 50 / 20 mL/kg/day per tier. Example 25 kg: (10×4)+(10×2)+(5×1) = 65 mL/hr → 1,560 mL/day. Enter weight in the calculator for step-by-step arithmetic and age-specific notes.

What are the Holliday-Segar weight breakpoints?

Exact tier ends: 10 kg = 40 mL/hr (960 mL/day); 20 kg = 60 mL/hr (1,440 mL/day). Above 20 kg add 1 mL/hr per kg (e.g. 30 kg = 70, 50 kg = 90, 70 kg = 110 mL/hr). Many adult services still cap near 100–150 mL/hr even if 4-2-1 is higher.

What is the Holliday-Segar method?

Published by Holliday and Segar (1957), the method estimates maintenance water for patients who cannot drink—replacing urine (~60%), stool, and insensible losses. The 4-2-1 mnemonic matches decreasing metabolic cost per kg as body size grows. It remains a bedside standard in pediatrics and is often applied to adults as a starting point, though adults may also use 25–30 mL/kg/day or protocol caps (e.g. ≤150 mL/hr).

How do you calculate maintenance fluids for a pediatric patient?

Use actual body weight in kg (preterm/neonate protocols may differ day 1). 15 kg child: 40 + (5×2) = 50 mL/hr (1,200 mL/day). 8 kg infant: 8×4 = 32 mL/hr. Fluid choice is usually isotonic dextrose-saline per hospital policy (D5 0.9% NaCl). Add KCl ~20 mEq/L after urine output is established. Replace emesis/NG/diarrhea losses on top of maintenance. Reassess q8–12 h with exam, weight, and electrolytes.

What maintenance fluid rate for a 25 kg child?

25 kg → 40 (first 10 kg) + 20 (second 10 kg) + 5 (remaining 5 kg × 1) = 65 mL/hr, 1,560 mL/24 h. This matches the default demo on this page. Rates assume euvolemia and normal losses—fever often adds ~10% per °C >37, and ongoing losses are replaced separately.

What IV fluids are used for maintenance (not boluses)?

Common choices: D5 0.9% NaCl (isotonic maintenance, reduces hospital-acquired hyponatremia risk vs hypotonic alone in many guidelines), D5 0.45% NaCl (traditional pediatric fluid—monitor Na+), or balanced crystalloid per protocol. D5W alone without electrolytes is rarely sufficient long term. Potassium typically 20 mEq/L once K+ safe and UOP adequate. LR may be used when chloride or acid-base concerns exist—follow local formulary.

When should you adjust maintenance fluid rates?

Increase for fever (~10% per °C above 37), tachypnea, high ambient temperature, and measurable losses (vomit, NG output, diarrhea). Decrease for SIADH, heart failure, renal failure, post-op fluid restriction, or oliguria—calculated maintenance may be excessive. Neonates day 1 often start below full 4-2-1 and ramp per nursery protocol. Obese adults: consider ideal body weight so 4-2-1 does not over-prescribe volume.

What is the difference between maintenance and resuscitation fluids?

Maintenance = steady hourly infusion replacing normal losses in a stable NPO patient. Resuscitation = boluses (e.g. 10–20 mL/kg isotonic) for shock, severe dehydration, or acute deficit. After hemodynamic stabilization, transition to maintenance plus deficit replacement and ongoing loss replacement as separate math. This calculator does not compute bolus volumes—use a dehydration or sepsis protocol tool.

What is the maximum maintenance fluid rate for adults?

Many services cap maintenance near 100–150 mL/hr even if 4-2-1 exceeds that (e.g. 100 kg → 4-2-1 = 140 mL/hr). Alternative: 25–30 mL/kg/day using ideal body weight in obesity (70 kg IBW → ~1,750–2,100 mL/day ≈ 73–88 mL/hr). This page caps adolescent/adult selection at 150 mL/hr for teaching—always follow institutional policy.

How do you monitor maintenance IV fluid therapy?

Track intake vs output (I&O) daily, urine output target often 0.5–2 mL/kg/hr (lower acceptable in neonates per unit policy), daily weight (unexpected gain → fluid overload; loss → dehydration), vitals, exam (mucous membranes, cap refill, edema), and serum Na+, K+, Cl−, glucose, BUN/Cr every 12–24 h until stable. Adjust rate when Na drifts, UOP sustained low, or clinical status changes.

Are there special fluid rules for neonates?

Yes. Day 1 term neonates often receive 60–80 mL/kg/day, increasing toward 140–160 mL/kg/day by day 7—not always full Holliday-Segar on birth day. Preterm infants have higher insensible losses and may need 180–200 mL/kg/day under NICU protocols. The calculator still shows 4-2-1 math for weight but displays neonate warnings—always use NICU/nursery orders.

How does fever change maintenance fluid requirements?

Teaching rule: increase maintenance by ~10% for each 1°C body temperature above 37°C (or ~12% per °F above 98.6) because insensible losses rise. Example: baseline 65 mL/hr at 38°C → ~71.5 mL/hr (+10%). Antipyretics and source control also matter. Fever adjustment is in addition to replacing measured NG/emesis losses.

Is this maintenance fluid calculator medical advice?

No. It applies Holliday-Segar arithmetic for education. Prescribing requires licensed clinicians, institutional IV fluid protocols, and individual assessment. Electrolyte disorders, DKA, renal replacement, and TPN need specialized orders—not this page alone.

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IV fluids · Holliday-Segar / MDCalc-style

Maintenance Fluid Calculator

Direct answer — MDCalc maintenance fluids / 4-2-1

MDCalc maintenance fluids use the Holliday-Segar 4-2-1 rule: 4 mL/kg/hr for the first 10 kg + 2 for kg 11–20 + 1 for each kg above 20. Daily = hourly × 24 (or 100/50/20 mL/kg/day). Breakpoints: 10 kg → 40 mL/hr, 20 kg → 60 mL/hr, 25 kg → 65 mL/hr (1,560 mL/day). Maintenance only — not shock boluses. Holliday & Segar. Pediatrics. 1957. Not affiliated with MDCalc.

4-2-1 table and weight breakpoints first — then the interactive calculator. Last updated: August 9, 2026.

Holliday-Segar 4-2-1 table

Same bedside tiers used in MDCalc-style maintenance fluid tools.

Holliday-Segar weight segments
Weight segment	Hourly	Daily equivalent	Example
First 10 kg (≤10 kg)	4 mL/kg/hr	100 mL/kg/day	8 kg → 32 mL/hr (768 mL/day)
Next 10 kg (11–20 kg)	+2 mL/kg/hr	+50 mL/kg/day	15 kg → 40 + 10 = 50 mL/hr
Each kg above 20 kg	+1 mL/kg/hr	+20 mL/kg/day	25 kg → 40 + 20 + 5 = 65 mL/hr

Weight breakpoints

Exact rates at common tier ends and adult anchors.

Weight	mL/hr	mL/day	Note
10 kg	40	960	End of first tier: 10 × 4
20 kg	60	1,440	End of second tier: 40 + 20
30 kg	70	1,680	60 + 10 × 1
40 kg	80	1,920	60 + 20 × 1
50 kg	90	2,160	60 + 30 × 1
70 kg	110	2,640	Adult 4-2-1; many services cap ≤150 mL/hr
100 kg	140	3,360	4-2-1 uncapped; compare IBW / protocol

Rate by weight (quick chart)

Precomputed from this page's Holliday-Segar logic.

kg	mL/hr	mL/day	Arithmetic
5	20	480	5 × 4
8	32	768	All weight in first tier
10	40	960	Breakpoint: first tier complete
15	50	1,200	40 + (5 × 2)
20	60	1,440	Breakpoint: second tier complete
25	65	1,560	40 + 20 + (5 × 1)
30	70	1,680	40 + 20 + (10 × 1)
40	80	1,920	60 + 20
50	90	2,160	60 + 30
70	110	2,640	Adult 4-2-1; may cap in tool
100	140	3,360	Uncapped 4-2-1; often protocol-limited

Calculate your maintenance IV rate

Enter weight for the same 4-2-1 math as the tables above, with neonate/adult notes and an optional adult rate cap at 150 mL/hr.

Holliday-Segar table above the form

kg or lbs · neonate / child / adult guidance

Step-by-step calculation string

Maintenance fluid calculator

Holliday-Segar 4-2-1 hourly rate and 24-hour volume

Body weight

Weight unit

Age group (guidance)

Fluid requirements

Maintenance rate

65 mL/hr

24-hour volume

1,560 mL/day

Calculation

40 + 20 + 5.0 kg × 1 mL/kg/hr = 65.0 mL/hr

Standard maintenance for 25.0 kg using the 4-2-1 rule (Holliday-Segar).

•Use isotonic maintenance fluid per hospital policy (often D5 0.9% NaCl).
•Add KCl ~20 mEq/L after adequate urine output and normal potassium.
•Replace ongoing losses (emesis, diarrhea) in addition to maintenance.
•Reassess rate every 8–12 h with exam, UOP, and electrolytes.

Maintenance only—not bolus resuscitation. Adjust for losses, fever, and renal/cardiac status per protocol.

Maintenance only. Do not use for shock boluses, DKA protocols, or deficit replacement without separate calculations. Verify with your hospital IV fluid policy. Not affiliated with MDCalc.

Example rates (from calculator logic)

25 kg child

65 mL/hr

1,560 mL/day

8 kg infant

32 mL/hr

15 kg child

50 mL/hr

70 kg adult

110 mL/hr

4-2-1; may compare to 25–30 mL/kg/day

Maintenance vs resuscitation fluids

Aspect	Maintenance	Resuscitation
Purpose	Replace normal daily urine, stool, and insensible losses	Correct hypovolemia, shock, or large deficits quickly
Rate	Steady mL/hr (e.g. 50–65 mL/hr for 15–25 kg child)	Bolus 10–20 mL/kg over minutes—protocol specific
This tool	Holliday-Segar 4-2-1 only	Use separate dehydration/shock algorithms

Common maintenance IV fluids (teaching)

Fluid	Typical use
D5 0.9% NaCl (isotonic dextrose-saline)	Common maintenance in many hospitals; lowers hyponatremia risk vs hypotonic alone
D5 0.45% NaCl (half-normal + dextrose)	Traditional pediatric maintenance; monitor sodium
Balanced crystalloid (e.g. LR)	When chloride load or acid-base balance is a concern—follow protocol
Potassium	Typically 20 mEq/L after urine output confirmed and K+ safe

Fever and other rate adjustments

Trigger	Adjustment
Fever	+10% maintenance per °C above 37 (or ~12% per °F above 98.6) — teaching rule
Vomiting / NG losses	Replace measured output (mL for mL) plus maintenance
Diarrhea	Replace stool losses per protocol; stool volume often estimated
Tachypnea / burns	Increased insensible losses—individualize
SIADH / heart failure / renal failure	Often restrict below calculated maintenance—specialist guidance

Fever example: baseline 65 mL/hr at 38°C → ~71.5 mL/hr (+10% per °C above 37). Replace measured NG/emesis losses on top of maintenance.

Holliday-Segar formula (quick reference)

Hourly mL/hr = 4×(first 10 kg) + 2×(kg 11–20) + 1×(kg >20)

Daily mL/day = hourly × 24

References

Holliday MA, Segar WE. Pediatrics. 1957The maintenance need for water in parenteral fluid therapy — origin of the 4-2-1 / MDCalc-style maintenance fluid formula.
NICE NG29 — Intravenous fluid therapy in adultsPrinciples for maintenance vs resuscitation and fluid types.
AAP / pediatric hospital protocolsIsotonic maintenance and hyponatremia prevention themes.

For dehydration boluses and deficit math, see our pediatric dehydration calculator.

Worked example

25 kg child — default demo

Holliday-Segar step-by-step

40 + 20 + 5.0 kg × 1 mL/kg/hr = 65.0 mL/hr

Rate: 65 mL/hr · 24 h: 1,560 mL

Standard maintenance for 25.0 kg using the 4-2-1 rule (Holliday-Segar).

Frequently Asked Questions

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IV fluids · Holliday-Segar / MDCalc-style

Maintenance Fluid Calculator

Direct answer — MDCalc maintenance fluids / 4-2-1

4-2-1 table and weight breakpoints first — then the interactive calculator. Last updated: August 9, 2026.

Holliday-Segar 4-2-1 table

Same bedside tiers used in MDCalc-style maintenance fluid tools.

Holliday-Segar weight segments
Weight segment	Hourly	Daily equivalent	Example
First 10 kg (≤10 kg)	4 mL/kg/hr	100 mL/kg/day	8 kg → 32 mL/hr (768 mL/day)
Next 10 kg (11–20 kg)	+2 mL/kg/hr	+50 mL/kg/day	15 kg → 40 + 10 = 50 mL/hr
Each kg above 20 kg	+1 mL/kg/hr	+20 mL/kg/day	25 kg → 40 + 20 + 5 = 65 mL/hr

Weight breakpoints

Exact rates at common tier ends and adult anchors.

Weight	mL/hr	mL/day	Note
10 kg	40	960	End of first tier: 10 × 4
20 kg	60	1,440	End of second tier: 40 + 20
30 kg	70	1,680	60 + 10 × 1
40 kg	80	1,920	60 + 20 × 1
50 kg	90	2,160	60 + 30 × 1
70 kg	110	2,640	Adult 4-2-1; many services cap ≤150 mL/hr
100 kg	140	3,360	4-2-1 uncapped; compare IBW / protocol

Rate by weight (quick chart)

Precomputed from this page's Holliday-Segar logic.

kg	mL/hr	mL/day	Arithmetic
5	20	480	5 × 4
8	32	768	All weight in first tier
10	40	960	Breakpoint: first tier complete
15	50	1,200	40 + (5 × 2)
20	60	1,440	Breakpoint: second tier complete
25	65	1,560	40 + 20 + (5 × 1)
30	70	1,680	40 + 20 + (10 × 1)
40	80	1,920	60 + 20
50	90	2,160	60 + 30
70	110	2,640	Adult 4-2-1; may cap in tool
100	140	3,360	Uncapped 4-2-1; often protocol-limited

Calculate your maintenance IV rate

Enter weight for the same 4-2-1 math as the tables above, with neonate/adult notes and an optional adult rate cap at 150 mL/hr.

Holliday-Segar table above the form

kg or lbs · neonate / child / adult guidance

Step-by-step calculation string

Maintenance fluid calculator

Holliday-Segar 4-2-1 hourly rate and 24-hour volume

Body weight

Weight unit

Age group (guidance)

Fluid requirements

Maintenance rate

65 mL/hr

24-hour volume

1,560 mL/day

Calculation

40 + 20 + 5.0 kg × 1 mL/kg/hr = 65.0 mL/hr

Standard maintenance for 25.0 kg using the 4-2-1 rule (Holliday-Segar).

•Use isotonic maintenance fluid per hospital policy (often D5 0.9% NaCl).
•Add KCl ~20 mEq/L after adequate urine output and normal potassium.
•Replace ongoing losses (emesis, diarrhea) in addition to maintenance.
•Reassess rate every 8–12 h with exam, UOP, and electrolytes.

Maintenance only—not bolus resuscitation. Adjust for losses, fever, and renal/cardiac status per protocol.

Maintenance only. Do not use for shock boluses, DKA protocols, or deficit replacement without separate calculations. Verify with your hospital IV fluid policy. Not affiliated with MDCalc.

Example rates (from calculator logic)

25 kg child

65 mL/hr

1,560 mL/day

8 kg infant

32 mL/hr

15 kg child

50 mL/hr

70 kg adult

110 mL/hr

4-2-1; may compare to 25–30 mL/kg/day

Maintenance vs resuscitation fluids

Aspect	Maintenance	Resuscitation
Purpose	Replace normal daily urine, stool, and insensible losses	Correct hypovolemia, shock, or large deficits quickly
Rate	Steady mL/hr (e.g. 50–65 mL/hr for 15–25 kg child)	Bolus 10–20 mL/kg over minutes—protocol specific
This tool	Holliday-Segar 4-2-1 only	Use separate dehydration/shock algorithms

Common maintenance IV fluids (teaching)

Fluid	Typical use
D5 0.9% NaCl (isotonic dextrose-saline)	Common maintenance in many hospitals; lowers hyponatremia risk vs hypotonic alone
D5 0.45% NaCl (half-normal + dextrose)	Traditional pediatric maintenance; monitor sodium
Balanced crystalloid (e.g. LR)	When chloride load or acid-base balance is a concern—follow protocol
Potassium	Typically 20 mEq/L after urine output confirmed and K+ safe

Fever and other rate adjustments

Trigger	Adjustment
Fever	+10% maintenance per °C above 37 (or ~12% per °F above 98.6) — teaching rule
Vomiting / NG losses	Replace measured output (mL for mL) plus maintenance
Diarrhea	Replace stool losses per protocol; stool volume often estimated
Tachypnea / burns	Increased insensible losses—individualize
SIADH / heart failure / renal failure	Often restrict below calculated maintenance—specialist guidance

Fever example: baseline 65 mL/hr at 38°C → ~71.5 mL/hr (+10% per °C above 37). Replace measured NG/emesis losses on top of maintenance.

Holliday-Segar formula (quick reference)

Hourly mL/hr = 4×(first 10 kg) + 2×(kg 11–20) + 1×(kg >20)

Daily mL/day = hourly × 24

References

Holliday MA, Segar WE. Pediatrics. 1957The maintenance need for water in parenteral fluid therapy — origin of the 4-2-1 / MDCalc-style maintenance fluid formula.
NICE NG29 — Intravenous fluid therapy in adultsPrinciples for maintenance vs resuscitation and fluid types.
AAP / pediatric hospital protocolsIsotonic maintenance and hyponatremia prevention themes.