QTc Hodges Calculator
The formula
What the hodges qtc tells you
A simple linear rate correction — add 1.75 ms per beat above 60 — that behaves predictably across the physiologic range.
Calculation: QTc = QT + 1.75 × (HR − 60). Enter your inputs and every substitution is shown below the result.
Reading the result
When Hodges, Fridericia and Bazett disagree, the Bazett value is the outlier to distrust.
Rules of thumb: Normal same bands; used in ICH E14 QT studies
Limitations and best practice
The linear form diverges from reality at bradycardia extremes just as power laws do at tachycardia — pick by rate zone.
This calculator gives an estimate based on standard formulas; it is not professional financial, medical, legal or engineering advice. Verify anything you plan to act on with a qualified professional and your own records.
Frequently asked questions
Why use Hodges?
Does Hodges beat Fridericia?
Source & methodology
Hodges 1983.
QTc Hodges explained: formula, worked example and honest limits
You are here because you need a specific number, and you want to see how it was produced before you rely on it. There are plenty of pages about QTc Hodges; almost none of them show the working. This one does: the formula, every input, a fully computed example, and a sensitivity analysis calculated live from this engine’s own defaults.
The number itself is the easy part. What takes judgement is knowing which inputs are facts in your situation and which are guesses wearing a decimal point — a distinction this page makes explicit for every field above.
A calculation like this one is worth roughly as much as a careful sentence: it forces several vague considerations into one comparable quantity. Once QTc Hodges is on the table, the argument can stop being about impressions.
Every figure in the prose is generated by the engine rather than written beside it — the worked example resolves to qTc (Hodges) = 467 ms on the default inputs, and the sensitivity section ranks the inputs that move the result — Measured QT first, at ≈9.1 % of the headline for a ten-percent error either way in that input — which is the thread the rest of this guide pulls on.
Inside the QTc Hodges calculation: formula and every input
Here is the complete model this tool runs — QTc = QT + 1.75 × (HR − 60) — with each input explained below. If a competitor’s page gives you a different answer from the same inputs, this is the text that settles which of you is right.
Measured QT (ms) (example value 425) is a quantity rather than a category — precision here is cheap and worth having. Replace the example with the figure from your own records — the tool recomputes instantly and the printed steps follow your numbers.
Heart rate (bpm) (example value 84) is a plain measured quantity — the unit shown in the label is the unit the formula expects. Enter it exactly as your document states it — quoted annual, monthly and effective rates are three different numbers.
QTc Hodges with real numbers, step by step
The tool prints its own working; this is the same arithmetic on the example values, reproduced so you can follow it by hand. Starting figures: Measured QT (ms), Heart rate (bpm). Run to the end, the qTc (Hodges) resolves to 467 ms — Hodges’ linear rate correction gives 467 ms — linear models stay stable across rates, which is why FDA cardiac-safety guidance likes them on the bands this tool uses.
- HR − 60 = 24
- QTc = 425 + 1.75 × 24 = 467 ms
- Three methods bracket the answer: 467 (Hodges) / 475 (Fridericia) / 503 (Bazett)
Bazett at this rate — 503 ms. Compare it against the main result of 467 ms before drawing conclusions.
Fridericia at this rate — 475 ms. This is the number experienced users quote when the headline alone would mislead.
Risk band — prolonged. Compare it against the main result of 467 ms before drawing conclusions.
Method — linear. If your inputs change, this is usually the first companion figure to move.
Re-running with your own figures is instant; re-running by hand once is the best way to know the tool is telling you the truth.
The QTc Hodges corridor: your result across a realistic band
The honest version of any estimate is a corridor, and this one is cheap to produce: QTc Hodges was recomputed at 5 points along the dominant input, with every other field left untouched.
| Measured QT setting | QTc (Hodges) |
|---|---|
| 80 % of the example value | 382 ms |
| 90 % of the example value | 425 ms |
| example inputs | 467 ms |
| 110 % of the example value | 510 ms |
| 120 % of the example value | 552 ms |
Across 5 settings of Measured QT, the result spans 382 ms to 552 ms. A decision that only works at one row of this table is a decision waiting for an input to move. Reproduce it in the form above by editing Measured QT alone; the substitution steps will follow your figures exactly.
Sensitivity: which inputs change QTc Hodges the most
Nobody should have to guess which input matters. The engine was re-run once per field below — ten percent up, ten percent down, everything else frozen — and the results ranked by how far they moved the qTc (Hodges). It is the fastest honest answer to “what matters most in QTc Hodges?” — and it is specific to these defaults, because sensitivity moves with the starting point.
- Nudge Measured QT by ±10 % and QTc Hodges lands between 425 ms and 510 ms (sensitivity ≈9.1 %)
- Nudge Heart rate by ±10 % and QTc Hodges lands between 452 ms and 482 ms (sensitivity ≈3.1 %)
Measured QT is the dominant lever here: ten percent either way moves the result by about 9.1 %, from 425 ms to 510 ms. That is where a careless figure does the most damage, so check it against a source, and treat Heart rate as the second priority (≈3.1 % per ten percent). Everything below that can stay approximate, which is a licence to stop chasing data that would not change the decision.
Reading the result: bands, zones and thresholds
The value above only becomes useful the moment you know what it is being measured against. The verdict attached to the default calculation — “Hodges’ linear rate correction gives 467 ms — linear models stay stable across rates, which is why FDA cardiac-safety guidance likes them” — is one band on a ladder your own figure may sit somewhere else on. The sensitivity list shows how far a modest input error moves you along that ladder: for Measured QT, ±10 % covers 425 ms to 510 ms. The practical reading rules: ask what would have to change to move you one band. If the answer is “a small, plausible input difference”, the band itself is not the finding — the uncertainty is.
Set QTc Hodges beside its neighbours and it usually plays a specific role: this figure establishes the size of something, and the neighbouring tools establish whether that size is acceptable. Skipping the first step makes the second one arbitrary.
The errors that quietly break a QTc Hodges figure
The linear form diverges from reality at bradycardia extremes just as power laws do at tachycardia — pick by rate zone. This calculator gives an estimate based on standard formulas; it is not professional financial, medical, legal or engineering advice. Verify anything you plan to act on with a qualified professional and your own records.
Comparing a QTc Hodges computed here with a figure from another source that uses different conventions. Same name, different denominator — the disagreement is usually in the definitions, not the data.
This model has its own particular trap: Measured QT carries ≈9.1 % of the response per ten percent of error, so effort spent elsewhere is largely decorative.
The subtlest error is answering the wrong question precisely. Confirm that qTc (Hodges) is actually the quantity your decision needs — the arithmetic is flawless either way, which is what makes the mistake invisible.
A quick check for any QTc Hodges figure
- State, in one sentence, which convention each rate, unit or period in the form is using.
- Compare the output against one published benchmark or a colleague’s independent estimate.
- Put Measured QT under a magnifier; the sensitivity table above is the reason why.
- Recompute once with the dominant input deliberately set low, and see whether the decision changes.
- Check that every field the formula needs actually arrived from a document, not from recollection.
- Confirm the answer against one independent method or published benchmark for QTc Hodges.
A routine for decision-grade QTc Hodges
The tool does the arithmetic; the routine below is what makes the arithmetic trustworthy. Five steps, a minute total — and afterwards you will know not just what the number is, but which assumption produced it.
Step 1 — start from evidence. The inputs behind QTc Hodges are measured qt (ms), heart rate (bpm). Write them down with their source next to each one; if you cannot name where a figure came from, that is the input most likely to be wrong. Write the assumptions in the same file as the result, and future arguments take minutes instead of meetings.
Step 2 — compute the version you would not be embarrassed by. If a stranger audited your inputs, which set would you hand over? Enter that set, read the result, and treat everything else as upside. The inputs are the part of the work that nobody else can do for you.
Step 3 — isolate your variables. Change one field, observe, revert. The live sensitivity list does the ranking for the default inputs; verify it against your own, because dominance shifts when the starting point shifts. Half of a good calculation is knowing which input you would hate to be wrong about.
Step 4 — run the scenario trio. Expected, pessimistic, optimistic. The gap between pessimistic and expected is the number to plan against; the optimistic result is useful only as a ceiling. Say the answer out loud before you save it; if it sounds wrong, the model did not change, your understanding did.
Step 5 — write the one-line memo. “QTc (Hodges) = 467 ms on this date, from these inputs.” That line is the entire deliverable; everything else on this page is how you earned the right to write it. One decimal place more than your data supports is one decimal place of fiction.
Who actually uses QTc Hodges — and when
Most Clinical Calculators disagreements are arithmetic disagreements in disguise. When QTc (Hodges) of 467 ms sits on the table with its working shown, the conversation stops being about who sounds more confident and starts being about which input is wrong. Numbers are cheap to produce and expensive to retract; the extra minute is the cheapest insurance available.
Professionals in Clinical Calculators use this style of calculation as a screening filter before spending real money or effort: a quick QTc Hodges check eliminates weak options in minutes, and the survivors earn the deeper, slower analysis. Estimates improve most when the worst case is written down in ink.
There is a personal-administration use people overlook: periodic self-checking. QTc Hodges quietly drifts as life changes — rates move, bodies change, costs compound — and re-running it a few times a year catches drift while correction is still cheap. A result worth acting on survives having its two shakiest inputs halved.
People also ask about QTc Hodges
What affects QTc Hodges the most?
The short answer: Measured QT. The longer answer is the sensitivity table on this page, where every numeric input was probed by ten percent and the qTc (Hodges) recalculated — Measured QT moved it furthest, by roughly 9.1 % (425 ms to 510 ms).
Which matters more: heart rate or measured qt?
Measured QT, by a factor of about 2.9. Concretely: ten percent on Measured QT is worth ≈9.1 % of QTc Hodges, the same nudge on Heart rate only ≈3.1 %. That ranking is re-computed for each page from that page’s own defaults.
What is a typical QTc Hodges?
On the worked example above QTc Hodges comes out at 467 ms. Treat that as one point on a distribution rather than a norm: the bands, the companion outputs and the sensitivity ranking tell you how wide the plausible range really is.
How do I calculate QTc Hodges by hand?
QTc = QT + 1.75 × (HR − 60) is the entire method. Work the inputs in that order — HR − 60 = 24 — and you will reach 467 ms on the default figures, the same number this tool prints.
What happens to QTc Hodges if measured qt changes by 10 %?
On these inputs a ±10 % change in measured qt takes QTc Hodges to 510 ms against the 467 ms example — around 9.1 % of the headline. The same test on every other field is in the sensitivity section.
Is the QTc Hodges result of 467 ms good or bad?
Neither, on its own — the label “Hodges’ linear rate correction gives 467 ms — linear models stay stable across rates, which is why FDA cardiac-safety guidance likes them” is the band this figure falls in for the example inputs, and your own inputs will place you elsewhere on the same ladder. Judge the number against your history and your alternatives, and remember that a ten-percent error in Measured QT alone moves it by ≈9.1 %.
How accurate is QTc Hodges for me personally?
The formula encodes averages; body-composition and measurement error typically shifts results by a few percent in either direction. Use ranges and trends, and treat any single 467 ms as approximate.
When should I take QTc Hodges to a professional?
Whenever the verdict band is far from your everyday range, or the inputs include medication-influenced values. QTc Hodges is a screening lens — a clinician holds the diagnostic instruments.
Why use Hodges?
It is linear and stable in the 50–120 bpm range, matching how ICH E14 QT studies model rate dependence.
Does Hodges beat Fridericia?
Near-identical in the mid-rate range; Fridericia edges ahead at bradycardia, Hodges at moderate tachycardia.
Do I need an account to use this QTc Hodges calculator?
No, and no data leaves the tab. The engine runs in the page itself, which is why the worked example, the bands and the sensitivity ranking all respond instantly to your keystrokes.
What the labels on this page mean
- Bazett at this rate
- 503 ms on the example inputs — a companion figure printed beside the headline of QTc Hodges so that no result is read in isolation.
- Fridericia at this rate
- 475 ms in the default QTc Hodges calculation — one of the secondary figures an experienced reader checks before trusting the primary number.
- Risk band
- prolonged in the default QTc Hodges calculation — one of the secondary figures an experienced reader checks before trusting the primary number.
- QTc (Hodges)
- The primary output of this tool: 467 ms for the default inputs, computed exactly from QTc = QT + 1.75 × (HR − 60).
- Worked example
- Every substitution in order, from the example inputs to 467 ms — the audit trail for the headline figure.
- Verdict band
- The interpretation attached to a result (“Hodges’ linear rate correction gives 467 ms — linear models stay stable across rates, which is why FDA cardiac-safety guidance likes them” on these inputs), which turns a bare number into a position on a scale.
- Sensitivity (±10 %)
- How far the QTc Hodges moves when a single input is nudged ten percent either way; the ranked list on this page is computed live from this engine.
Method, sources and what this tool cannot tell you
The model is published arithmetic implemented exactly as written: QTc = QT + 1.75 × (HR − 60). Source of record: Hodges 1983. Where a professional version of this calculation differs, it differs in inputs and jurisdiction-specific coefficients, not in the algebra — which is why re-checking your inputs beats hunting for a second calculator.
This page is an estimation aid, not professional advice. The design rule is simple: two people entering identical figures must get identical answers. Nothing is smoothed, weighted or adjusted behind the scenes; where judgement enters, this page says so and names the input responsible.
What to do with your QTc Hodges next
Save the number together with its inputs and today’s date; a QTc Hodges figure without context is unusable the moment an input changes.
Whoever you are (people who need one trustworthy number before their next decision), the next step is the same: replace the example inputs with your own, note the date, and re-run whenever a figure moves. In Health & Medical, a dated figure is a trend, and an undated one is a rumour.