Anesthesia Dosage Calculator

Patient & Settings

Patient label (optional)

Used in downloads; avoid personal identifiers.

Age (years)

Sex

Weight (kg)

Height (cm)

Required for ideal/adjusted dosing weight.

ASA Class

Weight basis for mg/kg scaling

Drug-specific exceptions may apply.

Rounding step

Applies to dose and volume outputs.

Guardrails

Respect max dose caps (when set)

Max dose caps are optional and editable per drug.

Frail / high sensitivity

Hepatic impairment

Renal impairment

Opioid-naïve patient

Pregnant

These modifiers are generic and conservative. Many drugs require individualized adjustments.

Drug Library (Editable)

Default values are typical examples; change them to match your protocol.

Use	Drug	Category	Unit	Min	Max	Concentration	Max dose (mg)
						mg/mL or mcg/mL	Opioids: mg cap
						mg/mL or mcg/mL	Opioids: mg cap
						mg/mL or mcg/mL	Opioids: mg cap
						mg/mL or mcg/mL	Opioids: mg cap
						mg/mL or mcg/mL	Opioids: mg cap
						mg/mL or mcg/mL	Opioids: mg cap
						mg/mL or mcg/mL	Opioids: mg cap

Results appear above this form after you calculate.

Example Data Table

These examples are fictitious and meant to show formatting only.

Case	Age	Sex	Wt (kg)	Ht (cm)	ASA	Basis	Propofol Range (mg)	Fentanyl Range (mcg)
Demo A	35	M	70	170	II	Actual	70–175	70–140
Demo B	72	F	82	160	III	Adjusted	52–130	50–100
Demo C	54	M	110	178	II	Ideal	75–188	75–150

The calculator will compute these values dynamically from your inputs and editable drug settings.

Formula Used

Base dose range: Dose = (min…max) × dosing_weight (mg/kg or mcg/kg).
Global modifier: Multiplies dose to reflect sensitivity flags (age, ASA, frailty, hepatic/renal). This is a conservative generic scaler.
Ideal body weight (Devine): IBW = 50 + 2.3×(inches−60) (male), 45.5 + 2.3×(inches−60) (female).
Adjusted body weight: AdjBW = IBW + 0.4×(Actual−IBW).
Volume conversion: mL = dose / concentration using mg/mL or mcg/mL.
Rounding: Values are rounded to the selected step for easier preparation.

Many anesthetic agents use different weight scalars (e.g., lean body weight) and patient-specific titration. Treat the modifier and basis as configurable tools—not fixed recommendations.

How to Use This Calculator

Enter patient age, sex, weight, and height (height is needed for ideal/adjusted weight).
Select the dosing weight basis that matches your protocol for the chosen drug(s).
Check sensitivity flags only when clinically appropriate; keep them off if unsure.
In the Drug Library, tick “Use” for the drugs you want and edit ranges/concentrations as needed.
Click Calculate. Review the dose and volume ranges shown above.
Download a CSV/PDF for documentation, then verify everything clinically.

Clinical Notes

Dose Range Structure

The calculator outputs a minimum–maximum range per drug based on your editable table. For mg/kg agents, it multiplies the selected mg/kg limits by dosing weight. For mcg/kg agents, it multiplies mcg/kg limits by dosing weight. This design supports protocol-driven titration rather than a single “correct” number.

Weight Basis Selection

Weight basis changes the dosing weight used in scaling. Actual weight is direct input. Ideal weight uses the Devine method derived from height and sex. Adjusted weight uses IBW plus 0.4 of the excess weight over IBW. When obesity or low muscle mass is present, reviewing the basis per drug can reduce outlier doses.

Modifier Transparency

Sensitivity flags apply a conservative global modifier that reduces the computed range. Older age, higher ASA class, frailty, hepatic impairment, renal impairment, and pregnancy each apply a modest reduction. For opioid entries, an additional opioid‑naïve reduction can be applied. These modifiers are intentionally visible so teams can audit what changed and why.

Concentration to Volume Conversion

If a concentration is supplied, the tool converts dose to volume using mL = dose ÷ concentration. Concentration can represent mg/mL for most agents or mcg/mL for opioids. Volume ranges help preparation, syringe labeling, and handoff communication. If concentration is blank, the calculator leaves volume empty to avoid accidental assumptions.

Rounding and Preparation Workflow

Rounding aligns outputs with practical preparation steps. Selecting 0.1 may match common syringe increments, while 1.0 supports quick mental checks. Rounding applies to both dose and volume. Use rounding as a presentation layer, not as a dosing rule, and confirm that rounding does not exceed any institutional maximums.

Export and Audit Readiness

CSV export supports spreadsheets, checklists, and charting. PDF export supports documentation and review. Each export includes the calculation timestamp, basis, modifier, and drug rows used for computation. This structure improves reproducibility across teams and helps quality reviews when practice changes require protocol updates review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review review.

FAQs

1) Is this a prescription tool?

No. It’s an educational calculator for double-checking ranges and converting volumes. Always follow institutional protocols and clinician judgment for final dosing decisions.

2) Why do I see “mixed units” in the chart?

If you select drugs using both mg and mcg outputs, the visualization labels the axis as mixed units. Consider charting mg and mcg drugs separately for clearer comparison.

3) When should I use ideal or adjusted weight?

Some protocols recommend IBW or adjusted weight for specific agents in obesity or unusual body composition. Use the basis that matches your local guideline for each drug.

4) What do the modifiers represent?

They are conservative sensitivity reductions for factors like age, ASA class, frailty, and organ impairment. They are not drug-specific pharmacokinetic models and must be validated clinically.

5) Can I add my own drugs or concentrations?

Yes. Use “Add custom drug,” then set your protocol ranges, units, concentration, and optional max cap. Select “Use” to include it in results and exports.

6) How are volume ranges calculated?

When concentration is provided, the calculator divides the dose range by concentration to estimate mL range. If concentration is blank or zero, volume remains empty to prevent assumptions.