Skip to content
ENExplore Calculators

QT Interval Correction (QTc) Calculator

Work out qt interval correction (qtc) instantly with clear inputs, formula shown and shareable results.

About QT Interval Correction (QTc) Calculator

Corrects a measured QT interval for heart rate using the Bazett, Fridericia and Framingham formulae so the three can be compared.

Formula

Corrections

RR = 60/HR; Bazett QTc = QT/sqrt(RR); Fridericia QTc = QT/RR^(1/3); Framingham QTc = QT + 154(1 - RR)

Worked example

With the default values below, QT Interval Correction (QTc) Calculator returns QTc (Bazett) of 484.4. Change any input above and every figure here is recalculated in your browser.

Inputs used

Measured QT intervalaccepts 200–700 ms
400 ms
Heart rateaccepts 20–220 bpm
88 bpm

Results

QTc (Bazett)
484.4 ms
QTc (Fridericia)
454.5 ms
QTc (Framingham)
449.0 ms
Interpretation
Prolonged

Step by step

  1. 1Values used
  2. 2Corrections
  3. 3QTc (Bazett)= 484.4 ms
  4. 4QTc (Fridericia)= 454.5 ms
  5. 5QTc (Framingham)= 449.0 ms
  6. 6Interpretation= Prolonged

Assumptions and limits

  • The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 1 decimal place, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
  • Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.
  • This is an estimate for general information and not professional medical advice. See the full disclaimer for the limits that apply to this kind of calculator.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.

Frequently Asked Questions

Why are there three formulae?

Bazett over-corrects at fast rates and under-corrects at slow rates, so Fridericia and Framingham are often preferred outside 60-100 bpm.

What QTc is considered prolonged?

Commonly quoted thresholds are above 450 ms in men and 460 ms in women, with 500 ms marking markedly prolonged.

Related Calculators

QT Interval Correction (QTc) Calculator | Calcrivo