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Tags: Education , Game , Puzzles , Randomness , Text
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Bingo grid with a center free tile.

Bingo cards are square grids filled with short prompts drawn from a list, used for quick games in classrooms, workshops, and events. A custom bingo card maker helps you turn any topic list into neat cards that print cleanly and can be reproduced later with the same settings.

You provide the list, pick the grid size, choose whether to include a center tile, and generate one or many cards. Items are sampled to fill the grid, and you can save the result as a document or an image when you are ready.

A typical setup uses a 5 to 5 grid with a center tile and a list of short activities. Each card will show a different layout, and using a seed lets you recreate the same set another day.

If your list has fewer unique items than the grid requires, repeats will appear inside a card. Short, specific items read best on paper, and consistent capitalization makes scanning easier during play.

Set a seed for reproducibility, and use the shuffle control for fresh variations when you want a new draw from the same list.

Technical Details:

The generator observes a list of text items and a square size to construct a bingo board. A pseudorandom number generator (PRNG) determines item order in a way that can be reproduced from a seed, so the same inputs yield the same cards.

The primary quantity is the number of filled cells in the grid. From a list of unique items, the sampler draws without replacement until either the grid is filled or the list is exhausted, then cycles to reuse items only if more are required.

Results change with the seed, the list content, and the grid size. A center tile appears only on odd sizes when enabled, and it does not draw from the list. Multiple cards are independent draws that share the same base seed but use distinct per‑card streams.

Comparisons between runs are meaningful only when the list and settings match. The system does not score or verify gameplay and is not suitable for wagering.

  1. Normalize the list: convert tabs and commas to new lines, trim, drop empties, and remove exact duplicates while keeping order.
  2. Clamp settings: grid size 3 to 10, cell size 28 to 72, cards 1 to 100.
  3. Compute filled cells from the grid size and center‑tile choice.
  4. For each card, derive a per‑card PRNG from the base seed and shuffle the item list.
  5. Take as many items as needed; if insufficient, wrap around to reuse items.
  6. Fill the grid row by row, place the center tile when applicable, then randomly swap mirrored rows.
  7. Render the grid with optional column headers and prepare exports on demand.
Symbol Meaning Unit/Datatype Source
n Grid side length integer 3 to 10 Input
I Center tile indicator 0 or 1 Derived
c Filled‑cell count integer Derived
m Unique items in list integer Derived
k Number of cards integer 1 to 100 Input
s Base seed 32‑bit unsigned Derived from input
r PRNG for a card function Derived
c = n2 − I I = 1 if n is odd and center enabled , 0 otherwise
Worked example
n=5 I=1 (center enabled) c= 52−1=24
With 30 unique items, the sampler draws 24 without replacement, places a center tile, and renders a 5 to 5 card.

Validation & bounds from the interface:

Field Type Min Max Step/Pattern Error Text Placeholder
Title text — — — — BINGO
Items textarea — — Tabs/commas treated as new lines — One item per line
Upload list file — — .txt, .csv, .tsv — —
Grid size number 3 10 1 — —
Include center tile switch 0 1 — — —
Center tile text text — 20 chars — — FREE
Cell size range 28 72 2 — —
Cards number 1 100 1 — —
Column headers switch + text — — Default B I N G O — B I N G O
Template (color) select — — Classic, Pastel, Bold, Monochrome, High Contrast — —
Style (layout) select — — Standard, Compact, Spacious, Grid Lines, Lined — —
Font scale range 80 140 2 — —
Cards per page select 1 4 1, 2, 4 — —
Page size select — — A4, US Letter — —
Orientation select — — Auto, Portrait, Landscape — —
Margins number 0 — mm — —

I/O formats:

Input Accepted Families Output Encoding/Precision Rounding
Text list Typed lines; upload .txt, .csv, .tsv Rendered card Screen pixels —
Export image — PNG snapshot 2× capture scale —
Export document — PDF with 1, 2, or 4 per page Millimeters; two‑decimal placement Two‑decimal positions
Export table — CSV for current card Header row optional —

Randomness, seeds, and reproducibility:

  • Per‑card randomness comes from a 32‑bit PRNG seeded by a 32‑bit hash of your seed text.
  • Shuffle derives a new draw stream while keeping other settings unchanged.
  • The displayed seed is an eight‑digit hexadecimal value for quick reference.
  • Multiple cards use independent streams derived from the base seed and the card index.

Performance & complexity:

  • Shuffling and selection are linear in the number of items.
  • Rendering is proportional to grid area and export scale.
  • PDF export repeats capture for each card; memory use grows with card count.

Diagnostics & determinism:

  • Identical seed, list, and settings regenerate identical cards.
  • Changing any input or using Shuffle yields a new layout.
  • The on‑card footer shows the card index and seed for traceability.

Security considerations:

  • File names are sanitized to safe characters before download.
  • Untrusted text is rendered as text only; no code is executed from list items.
  • Exports include exactly what is visible; avoid sensitive content in shared files.

Privacy & compliance:

Processing occurs in the browser, including list parsing and exports. No data is transmitted or stored server‑side.

Outcomes are purely random and have no monetary value.

Assumptions & limitations:

  • Duplicates are removed before sampling; exact string match determines uniqueness.
  • If the list is shorter than the grid requires, items repeat to fill remaining cells.
  • Center tile appears only on odd sizes when enabled, using your provided text.
  • Headers default to B I N G O on 5 to 5; otherwise letters A to Z are used.
  • Row‑level swaps introduce variation but do not fully shuffle columns.
  • Font sizing adapts to cell and text length; very long strings may shrink visibly.
  • CSV export reflects the current card and optional header row only.
  • PDF orientation may be forced to portrait when placing four cards per page.

Edge cases & error sources:

  • Empty lists yield blank cells except a center tile when enabled.
  • Whitespace‑only lines are ignored after trimming.
  • Tabs and commas are treated as separators and become new lines.
  • Windows line endings are normalized to single new lines.
  • Grid, cell size, and card counts outside bounds are clamped to safe ranges.
  • Seed text is case‑sensitive and trimmed before hashing.
  • Very small lists cause repeated items inside a card.
  • Export requires the rendering layer; if unavailable, no file is produced.
  • Large card sets increase memory during capture and may slow export.
  • Header labels shorter than the column count are auto‑filled with defaults.

Step‑by‑Step Guide:

Bingo card generation starts with a clear list and a chosen grid size, then produces printable cards.

  1. Paste your list, one item per line. List
  2. Select the grid size. 3 to 10
  3. Toggle the center tile and set its text, if desired.
  4. Optionally enable column headers for quick scanning.
  5. Set the number of cards and press generate.
  6. Adjust style, size, and margins for your paper.
  7. Save as a PDF or image, or download the table for reference.
Example: A 5 to 5 with a center tile and 30 items creates cards with 24 unique prompts plus the center.

You now have reproducible cards ready for printing or sharing.

FAQ:

Is my data stored?

No. All parsing, layout, and exporting happen in the browser. Nothing is sent to a server.

Why do I see repeated items?

Repeats occur when the unique list is smaller than the grid needs. Add more items or use a smaller grid.

How does the seed work?

A text seed is hashed to a 32‑bit value used to drive the random draw. The same seed and settings reproduce the same cards.

Can I add custom column headers?

Yes. Provide labels separated by spaces. If labels run out, defaults fill the remaining columns.

What formats can I save?

Save a PDF with multiple cards per page, a PNG image of the current card, or a CSV of the current grid.

Does it work without a network?

Yes, once the page is loaded. All operations run locally, including exports.

How do I make a 3 by 3 card?

Set the grid size to 3, enter at least 9 items for best variety, then generate.

What does the seed shown on the card mean?

It is the eight‑character hexadecimal form of the active base seed, useful for reproducing the same layout later.

Troubleshooting:

  • Nothing happens on export: reload the page and try again.
  • PDF fits poorly: adjust margins or orientation and retry.
  • Text looks cramped: increase cell size or reduce font scale.
  • Headers misalign: ensure the number of labels meets the column count.
  • Unexpected repeats: add more unique items to the list.
  • Wrong paper size: change A4 or US Letter to match your printer.

Advanced Tips:

  • Keep items short so the font remains large and legible.
  • Use a seed to share exact layouts with colleagues.
  • Increase margins when placing multiple cards per page for easier cutting.
  • Prefer the high‑contrast theme for dim rooms or distance viewing.
  • Headers help players scan columns quickly in larger grids.
  • Shuffle after small text edits to refresh variety while keeping the seed.

Glossary:

Grid size (n)
The number of rows and columns in the square.
Center tile
A free space placed in the middle of odd‑sized grids.
Seed
Text used to initialize the random draw for reproducibility.
PRNG
Pseudorandom number generator that drives shuffling.
Sampler
The process that selects items to fill the grid.
CSV
Comma‑separated text table of the current card.