24-Hour Fluid Balance Calculator (Intake vs Output)
Tally a patient's 24-hour fluid intake (oral, IV, tube, blood/products) against output (urine, drains, NG, stool, insensible) and compute the net balance.
≈ 0.5 baseline; +10% per °C above 37; higher with tachypnoea.
Clinical decision support tool — confirm against the patient chart; not a substitute for clinical judgment. Insensible losses are estimates; actual loss varies with temperature, ventilation, and ambient humidity.
General calculation reads
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About this tool
A 24-hour fluid balance — total intake minus total output — is one of the most frequently asked questions on a ward round and one of the most error-prone arithmetic tasks at the bedside, because there are many small contributors that all add up. This tally sheet lists them in two columns: intake (oral, IV maintenance, IV piggyback meds, tube feeds, blood and blood products) on the left, output (urine, drains, NG aspirate, stool, vomit, blood loss, and an insensible-losses estimate based on weight) on the right. Type in millilitres for each, and the calculator sums each column, computes the net (positive = patient retaining fluid, negative = net loss), and reports urine output in mL/kg/h if you give a weight — a more useful number than total volume because the clinical thresholds (oliguria <0.5 mL/kg/h) are expressed that way. The default insensible-losses estimate is roughly 0.5 mL/kg/h (about 800–1000 mL/day for a 70 kg adult) and is editable. This is a clinical decision support tool — confirm against the chart; not a substitute for clinical judgment.
How to use it
- Enter each intake item in mL (skip what does not apply).
- Enter each output item in mL.
- Enter the patient weight in kg if you want urine output as mL/kg/h.
- Read the net balance, the urine output in mL/kg/h, and the column totals.
Frequently asked questions
- What counts as insensible losses?
- Water lost through skin (sweat, evaporation) and breath, not measurable. A rough estimate is 0.5 mL/kg/h, higher with fever (+10% per °C above 37) and tachypnoea. The tool defaults to 0.5 mL/kg/h and lets you override.
- What is normal urine output?
- Adults: ≥0.5 mL/kg/h is generally adequate; <0.5 mL/kg/h sustained for several hours is oliguria. Children/infants want closer to 1 mL/kg/h. These are protocol thresholds — interpret with context.
- Why does the net balance matter?
- It is a quick perfusion + volume status proxy. A large positive balance in a septic or post-op patient may indicate fluid overload; a negative balance in dehydration suggests under-resuscitation. Trends over days matter more than a single 24-hour value.
- Should I include blood and blood products as intake?
- Yes — packed cells, platelets, FFP, albumin all count toward intake. Volume on the bag label, not just the cellular content.
- How precise are these tallies in practice?
- Routinely off by 10–20% due to spillage, evaporation, missed inputs, drain leaks. Use the trend, not the single decimal place. The calculator reports exact arithmetic from what you entered; the limit is the chart, not the math.
- Is anything sent anywhere?
- No. All addition runs in your browser.