IV Drip Rate Calculator

Saline solution: dosing, rate and drip factor

0.9% NaCl saline (308 mOsm/L) is isotonic with plasma and the most common IV fluid. To calculate the infusion rate: mL/h = total volume ÷ time in hours; gtt/min = (mL · drip factor) ÷ (time in min) — common drip factors are 20 gtt/mL (macrodrip) or 60 gtt/mL (microdrip, pediatric). For pediatric maintenance, the Holliday–Segar rule gives 100 mL/kg/day for the first 10 kg + 50 mL/kg/day for 10–20 kg + 20 mL/kg/day beyond 20 kg. The 4–2–1 rule converts this to hourly rate: 4 mL/kg/h (first 10 kg) + 2 mL/kg/h (next 10) + 1 mL/kg/h (above 20). Adults need ~30–35 mL/kg/day. For hypovolemia, give a 20 mL/kg bolus over 10–20 minutes. Example: a 25 kg child needs (10·100) + (10·50) + (5·20) = 1,600 mL/day; at 20 gtt/mL drip factor, that's ≈ 22 gtt/min.

Applications in Brazilian healthcare

Saline is the workhorse of emergency rooms, ICUs and pediatric wards. 0.9% NaCl covers most resuscitation and maintenance scenarios; Ringer's Lactate is preferred in surgery and burn cases (Parkland formula: 4 mL × kg × % body surface burned in the first 24 h); 5% dextrose (SG 5%) provides free water and minimal calories. Also used in oncology to dilute chemotherapy, obstetrics for labor hydration, and nebulization with bronchodilators. ANVISA regulates production; major suppliers in Brazil include Fresenius, Halex Istar and Eurofarma.

FAQ

Macrodrip or microdrip? Macrodrip (20 gtt/mL) for adults and higher volumes; microdrip (60 gtt/mL) for pediatrics and precise low-rate infusions where every drop counts.

Why isotonic? 0.9% NaCl has osmolarity close to plasma (~290 mOsm/L), so it doesn't cause cells to swell or shrink. Hypotonic solutions can cause hemolysis; hypertonic ones draw water out of cells.

Can saline cause problems? Yes — large volumes can cause hyperchloremic acidosis due to the high chloride content. Balanced solutions like Ringer's Lactate or Plasma-Lyte are alternatives for large-volume resuscitation.

Is this calculator a medical prescription? No. It's a teaching/checking aid. Prescriptions must be written by a licensed physician based on clinical assessment.