What this calculator works out
This calculator expresses the number of recovered skeletal elements as a percentage of the number expected, giving a simple completeness figure.
It is a count, not an assessment. Which elements are present usually matters more than how many, and this figure treats a phalanx and a femur as equal. This is a teaching aid, not a casework tool.
Element counts
Before you use the figure
- The default expected count of 206 is the conventional adult figure. Actual counts vary with sesamoid and sutural bones, and differ substantially for subadults, where unfused elements are counted separately.
- Decide and record what counts as an element. Fragments, teeth and unfused epiphyses are handled differently by different protocols.
- The percentage says nothing about which elements are missing. Record that separately.
- Recovery percentage is not the same as preservation quality. Present but degraded elements still count.
Recovering the skull, pelvis and both femora gives a far better basis for analysis than recovering fifty hand and foot bones, yet the second scores higher on a simple count. Standard recording protocols use zonation systems that record which parts of which bones are present, precisely because a raw percentage obscures this.
How this calculator works
A percentage of counted elements:
Completeness = recovered elements ÷ expected elements × 100The calculator rejects a recovered count above the expected count. In practice that situation signals commingling — remains from more than one individual — which is a substantive finding rather than an input error, and is assessed by counting duplicated elements.
The subadult skeleton contains more separately counted elements than the adult figure, because epiphyses have not yet fused. Applying 206 to a juvenile understates completeness considerably.
Worked example: 150 of 206
Using the default figures — 150 elements recovered from an expected 206:
- Completeness: 72.8%
72.8% sounds substantial, and it may be. But the same figure results from a skeleton missing the skull, pelvis and both femora as from one missing fifty-six hand and foot bones, and those two recoveries support entirely different analyses. The percentage is a summary for a report; the element inventory is the working record.
Common mistakes
- Applying 206 to a subadult. More elements are counted before fusion.
- Treating the percentage as a measure of analytical value. Which elements matter more than how many.
- Counting fragments inconsistently. Decide the convention and record it.
- Ignoring duplicated elements. They indicate more than one individual.
- Confusing recovery with preservation. They are separate observations.
Frequently asked questions
Why 206 bones?
It is the conventional count for a typical adult, but it is not fixed. Sesamoid bones beyond the patellae vary between individuals, sutural bones in the skull are variable, and some people have an additional rib or vertebra. The figure is a convention for reporting rather than an anatomical constant.
How is commingling identified?
Primarily by duplication — two left femora indicate at least two individuals. Beyond that, analysts look at size and robusticity consistency, age indicators that do not match, and where available, DNA. The minimum number of individuals is established from the most frequently duplicated element.
What recording systems are used in practice?
Zonation systems, which divide each bone into defined zones and record which are present, are standard in both forensic and archaeological contexts. They capture partial recovery, which a whole-element count cannot, and make quantification comparable between analysts.
Does a low percentage limit what can be determined?
It depends entirely on what survived. Sex can often be determined from the pelvis alone, stature from a single long bone, and age from several indicators. A 20% recovery including the pelvis and a femur may support more conclusions than a 60% recovery of the extremities.
Is what I enter stored?
No. Counts are processed entirely in your browser and never transmitted or retained.
Related tools
References
- GOV.UK — Forensic Science Regulator codes of practice and recording standards
- National Institute for Health and Care Excellence — clinical guidance relevant to skeletal assessment
Sources are checked at publication and can change — how I choose and check references.