ProReckoner provides free clinical calculators trusted by nurses in Australia and worldwide. Every tool is built around the standard nursing formulas — from IV drip rate calculations and drug dosing to BMI assessment and shift hour tracking. All calculations are instant, work on any device, and support both metric and imperial units. No login or app download required.
IV & Fluids
3 toolsIV Drip Rate (Gravity)
Drops per minute for gravity-fed infusions. Select your giving set drop factor.
gtt/min = Volume (mL) × Drop factor ÷ (Time hrs × 60)
Example: 1500 mL, 10 hrs, 20 gtt/mL = 1500×20÷600 = 50 gtt/min
Infusion Time & Volume
Three-way calculator — find time remaining, total volume or flow rate from any two known values.
Volume = Rate × Time
Rate = Volume ÷ Time
Time = Volume ÷ Rate
Example: 2000 mL at 160 mL/hr → 2000÷160 = 12.5 hrs
Infusion Pump Rate (mL/hr)
mL/hr pump setting from volume and time ordered. Includes blood product 4-hour safety alert.
mL/hr = Volume ÷ Time (hours)
Blood products must complete within 4 hours of issue per international guidelines. Label bag with start time.
Medication
2 toolsTablet & Oral Liquid Dose
How many tablets or mL to give. SR ÷ SS × Volume — works for tablets, liquids and injections.
Amount = (SR ÷ SS) × Stock Volume
Liquid: 375 mg ordered, 250 mg/5 mL → (375÷250)×5 = 7.5 mL
Drug Dose by Weight (mg/kg)
Total dose and volume to administer from patient weight and prescribed mg/kg dose.
Total dose (mg) = Weight (kg) × Dose (mg/kg)
Volume (mL) = Total dose ÷ Stock (mg/mL)
Dilution & Reconstitution
2 toolsDrug Dilution Calculator
How much diluent to add to reach a target concentration. Common for morphine, heparin and potassium infusions.
Stock drawn = Drug required ÷ Stock concentration
Diluent = Final volume − Stock drawn
Example (morphine): 30 mg needed, stock 10 mg/mL, final 30 mLStock = 3 mL · Diluent = 27 mL saline
Reconstitution Calculator
Volume to draw up after adding diluent to a powdered vial. Enter displacement volume if stated on the label.
Concentration = Vial mg ÷ (Diluent + Displacement)
Volume to give = Ordered dose ÷ Concentration
Conversion
1 toolUnit Converter
Convert between common clinical units — weight, mass, volume, length and temperature.
× 1000: g→mg · mg→mcg · L→mL
÷ 1000: mg→g · mcg→mg · mL→L
lb→kg: × 0.4536 · °C→°F: ×9/5+32
Normal body temp: 36.1–37.2°C (97–99°F)
Assessment
1 toolBMI & Weight Status
BMI and clinical weight category per WHO guidelines. Includes adjusted ranges for older adults (65+).
BMI = Weight (kg) ÷ Height (m)²
For adults 65+, healthy BMI is 22–27 — higher than standard, as low BMI in older adults increases mortality risk.
Shift & Time
2 toolsShift Hours & Overtime
Total hours worked with break deduction and overtime flag. Handles overnight shifts.
Hours = (End − Start) − (Break ÷ 60)
Overnight example: start 22:00, finish 06:30 → enter end as 30.5
Military Time Converter
Convert between 12-hour AM/PM and 24-hour military time. Essential for correct medication documentation.
PM→24h: add 1200 (except 12PM=1200, 12AM=0000)