Which weight should I use — total body weight or ideal body weight?

For propofol and etomidate, total body weight (TBW) is used in most references for average-weight adults. In obese patients, lean body weight (LBW) or adjusted body weight is often preferred to avoid overdose; this calculator uses the weight you enter, so enter LBW if that is your clinical practice. Ketamine dosing is generally based on total body weight.

Why does propofol show a lower dose for elderly patients?

Elderly and hemodynamically compromised patients have reduced cardiac output and plasma protein binding, leading to higher free propofol concentrations. Doses are typically reduced by 30–50% (to 1–1.5 mg/kg) and given in slow incremental boluses to avoid hypotension.

Is etomidate safe for repeated doses?

Etomidate suppresses adrenocortical function via 11-beta-hydroxylase inhibition. A single induction dose causes transient suppression lasting 6–12 hours. It is not recommended for prolonged sedation infusions, but a single induction dose is widely accepted in high-risk patients.

Can I use this calculator for pediatric patients?

This calculator includes a pediatric dose range for each agent. Pediatric induction dosing requires additional weight confirmation, careful titration, and monitoring. Always verify against current pediatric anesthesia references and institutional guidelines.

Are these doses applicable during rapid sequence induction (RSI)?

The ranges displayed represent standard induction doses and are generally applicable to RSI. For RSI, the full induction dose is typically given as a single bolus rather than titrated. Etomidate and ketamine are common RSI choices due to hemodynamic stability.

Induction Dose Calculator

Enter patient weight and select an anesthetic agent to get the standard induction dose range for propofol, ketamine, or etomidate.

Patient & Agent

Patient Weight

Induction Agent

Propofol Standard: 1.5–2.5 mg/kg IV

Ketamine Standard: 1–2 mg/kg IV

Etomidate Standard: 0.2–0.3 mg/kg IV

Patient Category

Enter weight and select an agent to calculate the induction dose.

Clinical reminder: These ranges are reference values for a healthy adult unless otherwise noted. Always adjust for ASA status, age, comorbidities, premedication, and co-induction agents. Confirm against your institution's drug formulary and current references before administration.

Summary

Anesthetic induction doses are weight-based and vary by agent, patient population, and clinical context. This calculator provides standard adult induction dose ranges for three commonly used agents — propofol, ketamine, and etomidate — based on total body weight. Dose ranges reflect widely cited references; always adjust for ASA status, age, hemodynamic stability, and co-medications.

How it works

Enter the patient's weight in kilograms or pounds.
Select the induction agent: propofol, ketamine, or etomidate.
Choose the patient category (standard adult, elderly/compromised, or pediatric) to apply the appropriate dose range.
The calculator multiplies the mg/kg range by the entered weight to show the minimum and maximum dose.
Review the displayed dose range and notes before drawing up the drug.
Always confirm doses against your institution's protocols and current pharmacopeia.

Use cases

Quick bedside dose check before induction in the operating room.
Cross-checking a drawn-up dose against the standard range for the patient's weight.
Anesthesia resident and CRNA education on weight-based dosing principles.
Estimating doses during emergency airway management outside the OR.
Comparing dose requirements across different agents for a given patient weight.
Refreshing recall of dose ranges when switching between infrequently used agents.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu