Lidocaine Dose Calculator: Max Safe Dose by Weight
Enter the patient weight, drug concentration, and whether epinephrine is included to find the maximum allowable dose of lidocaine in milligrams and millilitres. Switch between kg and lb, or select a different amide local anesthetic. The step-by-step panel shows exactly how the limit is reached so clinicians can verify the math at a glance. This tool is for educational reference; always confirm dosing with local protocols and clinical judgment.
Formula
Worked example
A 70 kg patient receiving plain 1% lidocaine: dose limit = 4.5 mg/kg x 70 kg = 315 mg, but the absolute ceiling for plain lidocaine is 300 mg, so 300 mg applies. At 1% (10 mg/mL) that is 300 / 10 = 30 mL. With epinephrine the limit rises to 7 mg/kg x 70 kg = 490 mg (under the 500 mg ceiling), giving 49 mL at 1%.
How the lidocaine dose calculation works
The maximum safe dose of lidocaine has two components: a per-kilogram limit and a hard absolute ceiling. For plain lidocaine (no vasopressor) the per-kg limit is 4.5 mg/kg and the ceiling is 300 mg; with epinephrine they rise to 7 mg/kg and 500 mg. The calculator applies whichever is lower: weight-based or absolute.
Volume is derived by dividing the milligram maximum by the solution concentration in mg/mL. Because percentage concentration equals ten times mg/mL (a 1% solution is 10 mg/mL, a 2% solution is 20 mg/mL), doubling the concentration halves the allowable volume.
Plain vs epinephrine-containing formulations
Epinephrine acts as a vasoconstrictor, slowing absorption of the local anesthetic into the bloodstream and reducing peak plasma concentration. This is why regulatory and clinical bodies permit a higher dose when epinephrine is present. Standard dilutions are 1:100,000 (10 mcg/mL) or 1:200,000 (5 mcg/mL).
Epinephrine-containing formulations are contraindicated at end-arterial sites: fingers, toes, the tip of the nose, the ear pinnae, and the penis. Ischemic necrosis has been reported with injection at these sites. In patients with uncontrolled hypertension, cardiac arrhythmias, or severe coronary artery disease, discuss the risk-benefit ratio before using epinephrine.
Choosing the right weight basis
For patients with a body mass index above 30, the American Society of Regional Anesthesia (ASRA) recommends calculating the dose on lean body weight (LBW) rather than actual body weight. Fat tissue is poorly perfused and does not meaningfully increase drug distribution volume for these agents, so using actual weight in an obese patient risks calculating a dose that produces a dangerously high plasma concentration in the perfused compartment.
Lean body weight can be estimated with the Devine formula (men: 50 + 2.3 x (height in inches above 60); women: 45.5 + 2.3 x (height in inches above 60)) or measured more precisely with bioimpedance analysis. Enter the LBW value in the weight field and select "lean body weight" from the weight basis selector.
Recognizing and managing local anesthetic systemic toxicity (LAST)
LAST can occur even below the calculated maximum dose, most commonly from inadvertent intravascular injection rather than dose excess. Early neurological symptoms include perioral tingling, a metallic taste, tinnitus, and light-headedness. Progression leads to agitation, confusion, and seizures. Cardiovascular signs include widening QRS, arrhythmias, and cardiovascular collapse - these are more prominent with bupivacaine than lidocaine.
ASRA LAST management steps: stop injection immediately, call for help, prioritize airway management, treat seizures with benzodiazepines, and initiate 20% lipid emulsion (Intralipid) therapy. Bolus dose is 1.5 mL/kg IV over 1 minute, then 0.25 mL/kg/min infusion. Avoid propofol as a substitute. Cardiopulmonary bypass may be required for refractory cardiovascular collapse. Aspiration before and incremental injection during administration are the most effective preventive measures.
Comparing common amide local anesthetics
Lidocaine is the most versatile amide: fast onset (2-5 minutes), reliable block, and a predictable safety profile. Its duration is relatively short (30-120 minutes plain), which can be an advantage when a short procedure is anticipated. Bupivacaine offers a much longer duration (up to 8 hours with epinephrine) but has a narrower safety window, particularly for cardiac toxicity, which makes it less forgiving if an accidental intravascular injection occurs. Mepivacaine sits between the two in duration and is preferred in dental practice. Ropivacaine is structurally similar to bupivacaine but is less cardiotoxic at equivalent doses, making it common in epidural and regional blocks where larger volumes are used.
Amide local anesthetic maximum dose reference
| Drug | Plain (mg/kg) | Plain max (mg) | With epi (mg/kg) | With epi max (mg) | Onset | Duration |
|---|---|---|---|---|---|---|
| Lidocaine | 4.5 | 300 | 7.0 | 500 | Fast (2-5 min) | 30-120 min (120-240 with epi) |
| Bupivacaine | 2.5 | 175 | 3.0 | 225 | Slow (5-15 min) | 120-175 min (180-480 with epi) |
| Mepivacaine | 4.5 | 400 | 6.6 | 500 | Fast (3-5 min) | 45-90 min (120 with epi) |
| Ropivacaine | 3.0 | 225 | 4.0 | 225 | Medium (5-10 min) | 120-240 min (180-480 with epi) |
Standard adult limits. Use lean body weight for obese patients. Absolute ceilings apply regardless of weight. Source: Iowa Head and Neck Protocols, ASRA guidelines.
Frequently asked questions
What is the maximum dose of lidocaine without epinephrine?
The standard maximum dose of plain lidocaine is 4.5 mg/kg, not to exceed an absolute ceiling of 300 mg for subcutaneous or infiltration use. For a 70 kg patient that is 4.5 x 70 = 315 mg, capped to 300 mg. Some protocols cite 3 mg/kg for more conservative settings.
What is the maximum dose of lidocaine with epinephrine?
With epinephrine the maximum dose rises to 7 mg/kg with an absolute ceiling of 500 mg. For a 70 kg patient that is 7 x 70 = 490 mg (below the 500 mg ceiling, so the weight-based figure applies). Epinephrine slows systemic absorption and effectively extends the safe dose window.
How do I convert concentration percentage to mg/mL?
Multiply the percentage by 10. A 1% solution contains 10 mg/mL; a 2% solution contains 20 mg/mL; a 0.5% solution contains 5 mg/mL. This is a direct consequence of the definition: 1% w/v = 1 g per 100 mL = 10 mg per mL.
Should I use actual or lean body weight for obese patients?
ASRA recommends lean body weight for obese patients (BMI above 30) because adipose tissue is poorly perfused and does not proportionally distribute local anesthetics. Using actual body weight in a very heavy patient overstates the safe dose in the perfused tissue compartment. Enter the estimated lean weight in the calculator when this applies.
Can I use this calculator for spinal or epidural lidocaine?
No. Spinal and epidural dosing uses much smaller volumes at much lower concentrations and is governed by separate protocols based on block level, patient physiology, and adjuncts used. This calculator applies to infiltration, field block, and peripheral nerve block techniques only.
What is local anesthetic systemic toxicity (LAST)?
LAST is a potentially life-threatening reaction to high plasma concentrations of a local anesthetic, most often caused by inadvertent intravascular injection rather than exceeding the dose limit. Symptoms range from perioral tingling and tinnitus to seizures and cardiovascular collapse. Treatment includes stopping injection, securing the airway, and administering 20% lipid emulsion (Intralipid) per ASRA LAST guidelines.
Why does bupivacaine have a lower dose limit than lidocaine?
Bupivacaine binds more strongly and for longer to cardiac sodium channels, making its cardiotoxicity both more severe and harder to reverse than lidocaine toxicity. This narrow cardiac safety margin is why the per-kg limit (2.5 mg/kg plain) is about half that of lidocaine, and why ropivacaine - which has a similar duration but less cardiac affinity - is preferred for high-volume regional techniques.