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QTc Interval (Bazett)

QTc = QT / √RR. Free online QTc Interval (Bazett). Calculate qtc interval (bazett) online — fast, accurate, mobile-friendly, no signup needed.

QTc (ms)
460.086948

Derivation

  1. ├── 01GivenQT_ms = 420, hr = 72
  2. ├── 02Formulat / √(60 / a)
  3. └── 03Compute QTc (ms)460.086948
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§01What is

Understanding the QTc Interval (Bazett)

The QTc Interval (Bazett) computes QTc (ms) from 2 inputs: qt (ms), heart rate (bpm). QTc = QT / √RR.

Health metrics give us objective checkpoints against a body that can feel unreliable. Used alongside professional guidance — not in place of it — these numbers help you track progress and spot trends that matter. The QTc Interval (Bazett) sits in that toolkit — it QTc = QT / √RR. Enter your numbers above and the result updates instantly; every step of the math is shown in the Derivation panel so you can see exactly how the answer was reached.

§02The Formula

How it’s calculated

t / √(60 / a)

Where

QT_ms
QT (ms)
hr
Heart rate (bpm)
§03Practical Example

Step-by-step walkthrough

Scenario

Apply the formula to a realistic set of inputs: QT (ms) = 420, Heart rate (bpm) = 72.

  1. 01Start by noting the input — QT (ms): 420.
  2. 02Start by noting the input — Heart rate (bpm): 72.
  3. 03Substitute these values into the formula: t / √(60 / a)
  4. 04Compute QTc (ms): the calculator returns 460.087.
  5. 05Cross-check the answer by opening the Derivation panel above — every line of math is shown so you can follow the computation end-to-end.
§04Variants

Common QTc Interval (Bazett) Problems

The formula gets rearranged depending on which variable you need. Here are the patterns you’ll run into in the real world — find the one that matches your problem and follow the worked steps.

01 · PATTERN

QT (ms) halved

QT_ms = 210 (from 420)

Keep every other input at its default and halve the qt (ms). See how qtc (ms) responds.

  1. 01New QT (ms): 210
  2. 02Baseline QTc (ms): 460.087
  3. 03New QTc (ms): 230.043
  4. 04QTc (ms) decreases by 50% → use this sensitivity to plan for real-world variation.
02 · PATTERN

QT (ms) doubled

QT_ms = 840 (from 420)

Keep every other input at its default and double the qt (ms). See how qtc (ms) responds.

  1. 01New QT (ms): 840
  2. 02Baseline QTc (ms): 460.087
  3. 03New QTc (ms): 920.174
  4. 04QTc (ms) increases by 100% → use this sensitivity to plan for real-world variation.
03 · PATTERN

Heart rate (bpm) halved

hr = 36 (from 72)

Keep every other input at its default and halve the heart rate (bpm). See how qtc (ms) responds.

  1. 01New Heart rate (bpm): 36
  2. 02Baseline QTc (ms): 460.087
  3. 03New QTc (ms): 325.331
  4. 04QTc (ms) decreases by 29.3% → use this sensitivity to plan for real-world variation.
04 · PATTERN

Heart rate (bpm) doubled

hr = 144 (from 72)

Keep every other input at its default and double the heart rate (bpm). See how qtc (ms) responds.

  1. 01New Heart rate (bpm): 144
  2. 02Baseline QTc (ms): 460.087
  3. 03New QTc (ms): 650.661
  4. 04QTc (ms) increases by 41.4% → use this sensitivity to plan for real-world variation.
§05FAQ

Frequently asked questions

Yes. The calculator implements the standard formula as documented and returns exact floating-point results. No approximations are used unless noted in the formula.
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