What is the Hartford nomogram?

The Hartford nomogram is the most widely used guideline for once-daily aminoglycoside dosing. It uses a 7 mg/kg dose and selects the interval (q24h, q36h, or q48h) based on creatinine clearance. A 6–14 h post-dose level is then plotted on the nomogram to confirm the interval is appropriate for that patient.

How is dosing weight calculated?

Ideal body weight (IBW) is estimated with the Devine formula (50 kg + 2.3 × inches above 5 ft for males; 45.5 kg + 2.3 × inches for females). If actual body weight (ABW) ≤ 1.3 × IBW, ABW is used. If ABW > 1.3 × IBW (obese), an adjusted dosing weight DW = IBW + 0.4 × (ABW − IBW) is used to avoid toxicity from overdosing fat tissue.

How is creatinine clearance estimated?

CrCl is estimated with the Cockcroft-Gault equation: CrCl = [(140 − age) × weight × (0.85 if female)] ÷ (72 × SCr). A serum creatinine floor of 0.6 mg/dL is applied to avoid over-estimating CrCl in cachectic patients.

What peak and trough targets should I use?

Targets depend on indication. For UTI/pyelonephritis: peak 4–8 mg/L, trough < 1 mg/L (low-dose synergy). For serious infections/sepsis: peak 8–10 mg/L, trough < 1–2 mg/L. For endocarditis synergy: peak 3–4 mg/L, trough < 1 mg/L (low-dose). For CF/bronchiectasis: peak 10–12 mg/L, trough < 1 mg/L. These are guides; actual targets depend on MIC and institutional protocol.

When should once-daily dosing NOT be used?

Once-daily gentamicin is generally avoided in pregnancy, burns > 20% BSA, ascites, endocarditis (except low-dose synergy regimens under specialist guidance), and CrCl < 20 mL/min. Traditional dosing with pharmacokinetic monitoring is preferred in these situations.

Does this replace therapeutic drug monitoring?

No. Gentamicin requires serum level monitoring — peaks and troughs for traditional dosing, or a Hartford 6–14 h level for once-daily — to individualize therapy and prevent nephrotoxicity and ototoxicity. This calculator provides initial estimates only. All doses must be verified and adjusted by a licensed pharmacist or physician.

Gentamicin Dosing Calculator

Name: Gentamicin Dosing Calculator
Availability: InStock
Author: Nham Vu

Compute once-daily (7 mg/kg Hartford) and traditional (1.7 mg/kg q8h) gentamicin doses from actual weight, CrCl, and clinical indication — with peak/trough monitoring targets.

Patient Parameters

Age (years)

Sex

Height (cm)

Actual Weight (kg)

Serum Creatinine (mg/dL)

Clinical Indication

Educational reference only. All dosing results must be verified by a licensed pharmacist or physician before administration. This tool does not replace clinical judgment or therapeutic drug monitoring.

Enter patient data and click Calculate Dose

Summary

Compute once-daily (7 mg/kg Hartford) and traditional (1.7 mg/kg q8h) gentamicin doses from actual weight, CrCl, and clinical indication — with peak/trough monitoring targets.

How it works

Enter patient age, sex, height, and actual body weight.
Enter the serum creatinine to estimate creatinine clearance (Cockcroft-Gault).
Select the clinical indication to display appropriate peak and trough targets.
The calculator determines dosing weight — actual body weight (ABW) if not obese, or adjusted body weight (DW) if ABW > 1.3 × IBW.
Once-daily dose is computed at 7 mg/kg dosing weight; interval (q24h / q36h / q48h) is selected by CrCl using Hartford nomogram criteria.
Traditional dose is computed at 1.7 mg/kg (or 2 mg/kg for severe infections) per interval, with the interval lengthened for reduced CrCl.
Dose recommendations and peak/trough targets are shown side by side for clinical decision support.

Use cases

Calculate an initial once-daily gentamicin dose for gram-negative bacteremia.
Determine traditional q8h/q12h gentamicin dosing for a patient with mild renal impairment.
Look up indication-specific peak and trough targets before ordering monitoring levels.
Estimate CrCl from a bedside serum creatinine before selecting the dosing interval.
Support pharmacy students learning gentamicin pharmacokinetics and monitoring.
Cross-check a clinical dose recommendation during infectious disease rounds.
Assess dose adjustment needed for a renally impaired critically ill patient.
Review Hartford nomogram interval selection criteria at the point of care.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu