What this worksheet does — and what it does not
This worksheet multiplies an uncorrected interval by a correction factor you supply, and shows the result with an uncertainty band either side.
It does not implement the Henssge nomogram. It performs the arithmetic of applying a factor and a confidence interval, once you have obtained both from an appropriate published source. The factor is the science; this page is the multiplication. These tools are teaching aids. They are not validated for casework, and no result from them should appear in a statement, report or investigation.
Correction worksheet
Important limitation
This page does not reproduce or replace the Henssge nomogram. It only performs arithmetic after the user supplies the uncorrected interval and the case-appropriate correction factor.
Before you use it
- The corrective factor comes from Henssge's published tables and depends on body mass, clothing or covering, the surrounding medium and air movement. It cannot be guessed.
- Factors below 1.0 indicate faster cooling than the standard case — light clothing, air movement, immersion. Factors above 1.0 indicate slower cooling — heavy covering, still air, insulation.
- The default uncertainty of 2.8 hours is the published 95% confidence interval for the standard case under favourable conditions. It widens considerably otherwise.
- The nomogram itself requires body mass and both temperatures, and is read graphically or with validated software.
Henssge's model is calibrated for a standard case: an unclothed body of a given mass, in still air, on a thermally neutral surface. Real bodies are none of those things. The corrective factor scales the effective body mass to account for the difference, which is why the same measured temperature can correspond to very different intervals depending on the circumstances.
How this calculator works
A multiplication and a band:
Corrected interval = uncorrected interval × correction factor
Range = corrected interval ± stated uncertaintyThe uncertainty is a stated confidence interval, not a rounding allowance. Reporting a Henssge estimate without it is a misuse of the method — the interval is part of the result rather than a caveat attached to it.
The published figure of ±2.8 hours applies to the standard case. Where conditions are less favourable — unusual clothing, strong air movement, uncertain ambient temperature, immersion — the interval widens, in some circumstances to ±7 hours or more.
Worked example: a 10 hour uncorrected interval
Using the default figures — 10 hours uncorrected, a factor of 1.0, uncertainty of 2.8 hours:
- Corrected interval: 10 × 1.0 = 10.0 hours
- Illustrative range: 7.2 to 12.8 hours
A factor of 1.0 means the standard case, so nothing changes. Apply a factor of 1.4 for a heavily covered body in still air and the interval becomes 14 hours, ranging 11.2 to 16.8. Apply 0.7 for a lightly clothed body in moving air and it becomes 7 hours, ranging 4.2 to 9.8. Those two ranges do not overlap at all — from the same measured temperature. The factor is not a refinement, it is the answer.
Common mistakes
- Believing this implements Henssge. It applies a factor you supply; it does not derive one.
- Guessing the correction factor. It comes from published tables against specific conditions.
- Reporting the interval without the range. The confidence interval is part of the result.
- Using the standard ±2.8 hours in unfavourable conditions. The interval widens substantially.
- Applying the method beyond its validated range. It loses reliability as the body nears ambient.
Frequently asked questions
What is the Henssge nomogram?
A graphical method, published by Claus Henssge in the 1980s, for estimating the post-mortem interval from rectal temperature, ambient temperature and body mass, using a double-exponential cooling model. It is read by drawing a line between scales on a chart, and it produces both a point estimate and a confidence interval. It remains the most widely used temperature-based method in forensic pathology.
Where do correction factors come from?
Henssge's published tables, which give factors against combinations of clothing or covering, the surrounding medium — still air, moving air, still water, flowing water — and the surface the body rests on. They range from well below 0.5 for immersion in flowing water to above 2.0 for a heavily insulated body. A forensic pathologist selects the factor from the scene conditions.
How reliable is the method?
Under favourable conditions, well validated within its stated confidence interval — which is itself wide. The published ±2.8 hours for the standard case is a 95% interval, meaning one case in twenty falls outside it even when everything is done correctly. Reliability degrades sharply where ambient temperature is uncertain or variable, where the body has been moved, or where conditions do not match a tabulated case.
Why not just use software?
Validated implementations exist and are used. The reason to understand the arithmetic is that the software's output is only as good as the corrective factor entered, and selecting that factor requires judgement about the scene. Understanding what the number does is what makes the judgement possible.
Is what I enter stored?
No. Values are processed entirely in your browser and never transmitted or retained. Do not enter identifiable case information into any public website.
Related tools
References
- GOV.UK — Forensic Science Regulator codes of practice and method validation requirements
- National Institute for Health and Care Excellence — clinical guidance on body temperature measurement
Sources are checked at publication and can change — how I choose and check references.