Direct answer: build a Coverage matrix from creator-defined themes, formats and promise roles; mark which combinations are applicable; attach an approved asset ID to every covered cell; and calculate Coverage rate as covered applicable cells divided by total applicable cells. Send uncovered important cells to a Gap queue with evidence, owner and review date.
This calculator measures a creator-defined library. It does not name or store files, design backups, calculate production capacity, plan the first 30 posts, or recommend which content should be free or paid. Coverage describes structural presence in the declared matrix, not quality, freshness, demand, or sales value.
First define what the library is expected to support. A quality review belongs in the content quality checklist. An asset can pass structural coverage and still fail accuracy, presentation, consent, technical, or editorial checks.
Freeze the library scope and snapshot
Name the library, owner, snapshot date, included collection, excluded collection, approved status definition, and intended audience experience. Use one stable inventory export or manual snapshot. Do not count files added after the snapshot without issuing a new version.
Choose the unit of inventory: approved asset, approved set, or publishable content item. Do not mix units in one matrix. A raw clip, edited set, thumbnail, and final post should not become four covered cells when the unit is one publishable item.
Record duplicate and derivative rules. If one asset can legitimately cover two roles, cite it in both cells and explain why. Do not inflate coverage by counting filename variants that provide the same experience.
Define creator-owned themes
List three to seven active themes from the creator's current strategy. Give each an inclusion rule, exclusion rule, example, owner, and status. Themes should be specific enough that two reviewers can classify an asset consistently.
Do not add a theme solely because a competitor uses it. The matrix reflects the creator's approved promise. Retired and experimental themes can appear in a reference table but should not enter the active denominator unless explicitly included.
If an asset fits several themes, choose a primary theme and optional secondary theme. The matrix can reference both when each combination is applicable, but the evidence note should make the overlap visible.
Define formats by audience experience
Format labels might include still set, short video, extended video, written update, audio, or another creator-defined medium. Define minimum characteristics without turning the worksheet into a production specification.
Separate file type from format. An MP4 can be a short loop, full scene, or tutorial-style sequence. The audience experience and intended use determine the format row, while file properties belong in asset metadata.
Remove formats the creator does not provide. Empty cells for irrelevant formats create false gaps and lower the rate without representing an actual promise.
Add Promise role as a third dimension
Promise roles explain why an item exists: discovery, orientation, continuity, depth, completion, variation, or another defined role. Keep the list short and tied to the library purpose.
A theme-format pair can be present but one-dimensional. Promise roles reveal whether every item is an introduction while deeper or continuing value is absent. They also reveal unnecessary duplication where many assets perform the same job.
Use separate matrix tabs by role or one row per theme-format-role combination. Choose the representation reviewers can audit most reliably.
Mark applicable cells before counting coverage
For every possible combination, mark applicable, not applicable, or undecided. An applicable cell corresponds to an approved creator promise and feasible format. Not applicable requires a reason. Undecided stays outside the denominator until the responsible owner resolves it.
Freeze the applicability table before attaching assets. Otherwise a reviewer can mark empty cells not applicable merely to improve the rate. Changes after counting require a new matrix version and a decision note.
The denominator is the number of applicable cells, not every mathematical combination. This is why the worksheet reflects a creator-defined strategy rather than a universal completeness score.
Attach evidence and assign cell status
A covered cell needs at least one approved asset ID that meets the theme, format, and Promise role definitions at the snapshot date. Add last-reviewed date and reviewer. A filename without review is inventory, not coverage evidence.
Use covered, partial, uncovered, and stale as working statuses. Define partial precisely, such as an asset that fits theme and format but does not fulfil the declared role. Define stale using a creator-selected review rule, not an arbitrary universal age.
Only covered cells enter the numerator. Partial and stale cells remain visible in the queue. This conservative rule stops uncertain evidence from being silently treated as complete.
Calculate Coverage rate transparently
The formula is: Coverage rate = covered applicable cells divided by applicable cells, multiplied by 100. If 24 cells are applicable and 18 have approved evidence, the fictional example rate is 75 percent. Show 18 of 24 beside the percentage.
Do not calculate when the denominator is zero. Display “scope not defined.” If applicability is still changing, label the rate provisional and list undecided cells separately.
Calculate sub-rates by theme, format, and role to locate concentration. Do not average percentages with different denominators. Sum covered cells and applicable cells, then calculate the combined rate.
Build a Gap queue from uncovered cells
Every uncovered, partial, or stale applicable cell enters the Gap queue with matrix version, theme, format, role, status, evidence note, importance rule, estimated effort handoff, owner, decision, and review date. The queue is a decision list, not an automatic production order.
Prioritise using creator-defined relevance and evidence. A gap tied to a central promise may matter more than several optional cells. Mark keep open, create, revise, retire applicability, or defer, with a reason.
Send approved production items to the content calendar planning system. The matrix finds structural gaps but does not choose dates or claim capacity.
Run scenario and reviewer checks
Test a newly approved asset, a duplicate, a multi-theme item, a stale item, and an asset that fits no current role. Two reviewers should reach the same cell status from definitions and evidence. Resolve repeated disagreement by improving definitions.
Recalculate after a single controlled change and confirm the numerator, denominator, and sub-rate move as expected. Keep a before and after snapshot. Never type a percentage manually when it can be derived from the counted cells.
If the library is just beginning, use the first 30 posts planner separately. This calculator evaluates a defined library rather than prescribing its opening sequence.
Copy the calculator fields
Use: matrix ID; snapshot; theme; format; Promise role; applicability; applicability reason; asset ID; asset status; coverage status; review date; reviewer; evidence note; gap importance; queue decision; owner; and next review.
Publish counts with scope: covered cells, applicable cells, undecided cells, partial cells, stale cells, and snapshot date. A percentage without those details is not an auditable coverage statement.
Maintain versions without erasing old gaps
Issue a new matrix version when a theme, format, Promise role, applicability rule, or approved-status definition changes. Record the previous value, new value, reason, owner, and effective date. Do not recalculate an old snapshot under the new definition and present it as though the historical library had changed.
When a new asset covers a queued gap, attach its ID, review status, and completion date to the queue row. Then recalculate from the source cells. A gap closes because evidence changed, not because someone manually removed it from the list.
Keep retired cells in the change history. If an applicability decision removes a cell, report the effect on the denominator separately from the effect of adding coverage. Otherwise a rate can rise even though no content was added.
Use a concise change summary: added assets, revised definitions, applicability changes, expired evidence, numerator movement, denominator movement, and unresolved queue. This makes successive snapshots comparable without pretending the category system is permanent.
Interpret sub-rates with raw counts
A theme with one of one cells covered has a 100 percent sub-rate, but it carries less structural evidence than a theme with nine of ten. Always show the fraction. Do not rank themes by percentage alone when denominators differ sharply.
Use sub-rates to locate the kind of gap. A low format rate can reveal dependence on one medium. A low role rate can show that the library introduces themes but rarely provides continuity or depth. These are inventory observations, not audience preferences.
When one asset supports several cells, report both unique approved assets and covered cells. That distinction exposes concentration risk: apparent matrix breadth may depend on very few underlying items.
Limitations and sources
Limitations: coverage depends on creator-defined categories and reviewer consistency. It does not measure audience satisfaction, asset quality, uniqueness, production readiness, or commercial performance. Different matrices cannot be compared without aligning definitions.
The gap-mapping approach adapts GOV.UK guidance to map a whole problem and create evidence-led maps. The matrix, denominator rules, and queue are original SirenCY editorial tools.