What are dosage calculators, and how do I use them?

Dosage Calculators — How to Use Them

The Calculators page lets you convert between mg↔tablets↔mL, build pediatric liquid doses, compute IV infusion rates, mix bags, estimate renal function, dose by BSA, explore simple PK dosing, and convert opioids to MME. Educational use only — not for patient care.

Where to Find Them

1. From the Student dashboard, open Quick Launch → Calculators.
2. Pick the tool that matches your task (e.g., Weight-Based Dose, Pedi Liquid, IV Infusion Rate, etc.).

1) Weight-Based Dose (tablets + liquid)

Compute a per-dose amount from weight and optionally convert to tablets or liquid volume.

1. Enter Weight (kg) and desired Dose (mg/kg) (leave “max per dose” blank unless you need a cap).
2. Optional: enter Tablet strength (mg/tab) and choose tablet rounding (e.g., ½ tab).
   Optional: enter Liquid strength (mg/mL) and choose volume rounding (e.g., 0.1 mL).
3. Read the Calculated per-dose (mg), plus estimated tablets and/or liquid (mL).

• Common uses: adult/teen weight-based dosing, quick tablet conversions, liquid equivalents.
• Watch for: mg vs mcg; rounding that creates impractical doses; entering lb instead of kg.

2) Pediatric Liquid Dosing (mg/kg/dose)

Build a per-dose liquid regimen with a schedule and daily caps.

1. Enter Weight (kg) and Dose (mg/kg/dose).
2. Choose the Schedule (e.g., q8h, q12h, etc.).
3. Provide the Liquid strength (mg per mL) and pick rounding (0.1 mL typical).
4. Optional caps: set Max mg per dose and/or mg/kg/day.
5. Results show per-dose mg and volume (mL), plus per-day totals.

• Watch for: mixing up mg/kg/dose vs mg/kg/day; forgetting daily maximums from a reference.

3) IV Infusion Rate

Convert a weight-based or flat infusion dose into a pump rate (mL/hr) or drops/min.

1. Enter Weight (kg) (if using mg/kg/min) and the Desired dose (pick units, e.g., mcg/kg/min).
2. Provide the Bag concentration (e.g., mg in mL) and, if needed, a drip set (gtt/mL).
3. Read the Pump rate (mL/hr); optionally see gtt/min.

• Watch for: mcg vs mg, mL/hr vs gtt/min, and correct bag concentration (don’t mix up “amount in bag” vs “per mL”).

4) Bag Mixing Helper

Figure out how much diluent to add to reach a target concentration.

1. Enter the Drug amount on hand (mg) and the target concentration (mg/mL).
2. Option A: give a final volume → see achieved concentration and adjust.
   Option B: give the current volume → tool returns the required diluent to add.

• Watch for: using mL vs L; entering the powdered vial amount incorrectly.

5) Cockcroft–Gault CrCl & Dosing Weight

Estimate creatinine clearance and pick the dosing weight used in the equation.

1. Enter Age, Sex, SCr (mg/dL), Height (cm), and Weight (kg).
2. Choose the weight for CrCl (Auto picks IBW/ABW/AdjBW based on rules; you can override).
3. See IBW/ABW/AdjBW estimates and the resulting CrCl (mL/min).

• Watch for: unstable renal function; using non-steady-state SCr; rounding SCr up/down without policy.

6) BSA (Mosteller) & mg/m² Dosing

Compute BSA and (optionally) a dose based on mg/m².

1. Enter Height (cm) and Weight (kg).
2. Optional: enter a Target dose (mg/m²) and pick rounding.
3. Read BSA (m²) and the calculated dose (mg).

7) PK: Loading & Maintenance Dosing

Simplified PK tool for meds where you know Vd, CL, and desired target concentration.

1. Enter Weight (if Vd is L/kg), Vd, CL, Target C (mg/L), and Interval (h).
2. Get a suggested Loading dose and Maintenance (mg/hr or mg/qXh).

• Watch for: using appropriate units; the model is simplified and for education only.

8) Equianalgesic Converter (MME)

Educational only — not for patient care. Converts current opioid regimens to morphine milligram equivalents.

1. Select the opioid, route, and dose (mg) and frequency.
2. Optional: set a cross-tolerance reduction (many references suggest 25–50%).
3. View MME/day and per-dose equivalents.

• Not for: methadone, fentanyl, buprenorphine, or patches (per tool warning).

Safety & Best Practices

• Educational use only: The calculators are for exam prep and skill-building, not clinical decision-making.
• Verify with references: Always cross-check doses, caps, and schedules with trusted guidelines/texts.
• Units discipline: Re-read units for every field (mg vs mcg; mL vs L; mg/kg/dose vs mg/kg/day).
• Rounding: Match rounding to what you can actually dispense (½ tab, 0.1 mL, etc.).
• Copy with context: When you paste a result, include the units and schedule to avoid ambiguity.

Quick Workflow (At-a-Glance)

Dashboard → Calculators
Pick the calculator for your task
Enter inputs with correct units → choose rounding
Review results → Copy
Double-check with a trusted reference (educational only)

Disclaimer: Numbers shown by the tools are for educational simulation. They do not replace clinical judgment, institutional policies, or prescribing references.