Count bacterial colonies on an agar plate from a photo
Works with JPG, PNG, WEBP · Free up to 20 MB, Premium 50 MB
Spread the colonies one layer deep on a tray or flat surface and photograph from directly above — counted detections receive dots for review. Built for microbiology labs, QC teams and research groups — review and correct each photo before adding it to a CSV or PDF tally.
- Review the photo, then count visible colonies
- Count without marking; add example boxes if you need a guided recount
- Stop counting the same colonies twice to be sure of the total
- Free to use · No signup required · Without watermark
Works with JPG, PNG, WEBP · Free up to 20 MB, Premium 50 MB
Upload Image
Tips for an accurate count
• Use an even, well-lit photo with the colonies fully in frame
• Check that each marked example boxes a whole colonies rather than a repeated part
• Dots and heatmap show retained detections — review and correct the tally
About the Bacterial Colonies Counter
The bacterial colonies counter counts visible colonies from your photo and marks detections for review. Auto mode uses the selected item name. For a guided recount, mark up to three examples of what you want counted. Visibility, overlap and similar-looking items can affect the total. Built for microbiology labs, QC teams and research groups.
How It Works
1. Photograph your colonies
2. Check that colonies is selected, then choose Count
3. Review the markers and correct the tally; add example boxes for a guided recount if needed
4. Add to the tally sheet and export your count as CSV
Perfect For
• A fast draft CFU tally before the manual read is signed off
• Second-reader checks on plates near the countable range
• Keeping plate framing consistent across a study
• Teaching labs where every student counts the same plate
Colony counter app for a draft CFU tally from a plate photo
Microbiology labs, QC teams and teaching labs use this colony counter as a draft read of an agar plate: a fast tally before the manual count is signed off, a second reader on plates where the count is borderline, and a way to keep plate photos framed the same way across a study. It counts the colonies visible in the photo and marks each one; the number is yours to review, and it is not a validated instrument or a regulatory method.
Photograph the plate from directly above on a dark, non-reflective surface, with soft light from the side or a light box underneath. Condensation on the lid forms droplets that look a lot like small colonies, so take the lid off or shoot through the base with the plate inverted. The plate rim reflects light as a bright ring; crop to the agar with the image cropper before counting. Writing on the base shows through pale agar, so label the plate edge instead. In Similar items, mark two or three clear, well-separated colonies as examples, choosing different sizes if the plate mixes them.
Touching colonies are often read as one, so check every marker where growth meets and adjust the tally row by hand. Record each plate as a row labelled with sample and dilution; turning the count into CFU is your own calculation. For microscope fields rather than plates, the cell counter is the matching page.
Plate photo checks
- Lid off, or plate inverted, so condensation does not show
- Dark matte background and soft, even light
- Photo cropped to the agar so rim glare is out of frame
- Two or three clear colonies marked as examples
Frequently asked questions
- Do the items need to be separated before counting?
- Slight touching can work, but full overlaps hide items and make the result less reliable. Spread them one layer deep under even light, mark a clear example, and review every result marker.
- Can it separate colonies that have grown into each other?
- Merged growth is the hardest case and a confluent patch is often marked as one. Mark two or three clear, well-separated colonies as your examples, then review the markers and split or add any the counter merged. Plates read while the colonies are still discrete give the most reliable draft.
- What if the photo has more than just colonies in it?
- Auto mode uses the selected item name to find what to count. For a guided recount, mark one complete, clearly visible bacterial colonies — up to 3 examples for different-looking kinds. Similar-looking distractors can still affect the result, so review every marker before using the total.
- Can I count several photos into one total?
- Yes — count each photo and add every reviewed result to the tally sheet as a labelled row. If you use example boxes, mark them separately on each photo. Export the tally as CSV or a PDF report, or save it to your account.
- Is it free and private?
- Yes. You can count, review and download a free result without an account. Downloads are free without a watermark. No signup required. Server-processed photos are encrypted in transit and removed under our Security policy.
What you can do with Object Counter
Review the main capabilities before you begin.
- Count objects in a photo instead of tallying by hand
- Tally coins, pills, cells, parts and beads
- Optionally mark an example to target a specific item
- Review counted detections with overlay markers
- Run a bulk audit across many photos
- Fine-tune sensitivity to ignore tiny specks
Settings reference
12 settings
Available controls for Object Counter.
Upload
- Single photo / Bulk auditPresets
- Choose a single-photo count or a Premium bulk audit. Review every result.Options: Single photoBulk audit
Count
- Add to tallyOne-click
- Add this photo as a row in the current stock-take.
- Counting modePresets
- Chooses the counting engine: Auto and Similar items count from your marked examples — mark 1 to 3, one complete object per different-looking kind; Distinct objects labels separate, fully visible items without an example.Options: AutoSimilar itemsDistinct objects
- Included markersSliderRange: 0–1 · Default: 0.21
- Starts at 21%; slide toward Show more to include weaker markers or Only strongest to hide them.
- Overlay stylePresets
- Choose dots, a heatmap, both or a clean preview.Options: BothDotsHeatNone
- What to countText input
- Type the item to count, such as cow, bottle or car, so other objects in the photo are ignored; leave it blank to count everything.
- Detection sensitivitySliderRange: 0–1 · Default: 0.5
- Adjust detection sensitivity for larger or smaller visible items.
Examples
- Mark example itemsDraw on image
- Drag a tight box around one complete, clearly visible item. The counter uses it as a visual reference; review every result marker for lookalikes or missed items.
Tally
- LabelText input
- Rename this row so it is identifiable in the exported stock-take.
- CountNumber input
- Correct this row's count; totals and exports update automatically.
Advanced
- Result overlayDropdown
- Choose how count markers appear on the downloaded result.Options: Dots + heatmapDots onlyHeatmap only
- Ignore small detectionsSliderRange: 0–1 · Default: 0
- Ignore detections below the selected size.
Related tools for Object Counter
Tools for common next steps after Object Counter.
Counting & Inventory
Live Object Counter
Aim your phone at separated, fully visible items and review the detector markers as the count updates in real time.
Try it now
Counting & Inventory
People Counter
Estimate how many people appear in a photo. Review the markers and verify the count before official use.
Try it now
OCR & Data Extraction
Image to Text (OCR)
Extract editable text from a screenshot, photo or scan in 30+ supported languages.
Try it nowHow Object Counter helps you get it done
Real problems it solves every day — for businesses, creators, and everyday tasks. Find the use case that fits you and start.
Reviewed Warehouse Cycle Counts
Use Bulk audit to run Distinct objects mode across every shelf photo in the queue, review every result, and correct the per-shelf tally before exporting a cycle count.
Small-Parts Inventory for Makers & Etsy Sellers
Mark the bead, screw or component you need in the Examples setting — 1-3 examples, one per part type — then run the count. Review the matching markers for background mistakes, then add the corrected result to the tally sheet.
Classroom & Lab Supply Counts
Create an AI-assisted draft of dice, counters, test tubes or lab kits, then review and correct the markers before exporting a reorder tally.
Shareable Stock-Take Reports for Teams
Save a completed stock-take to your account, generate a branded PDF report, and share a read-only link so managers or teammates can review the count without re-uploading anything.
Batch QC Counts for Packed Finished Goods
Run Similar items mode after marking 1-3 example units in the Examples setting — one per pack type in the shot. Review every marker and correct misses or duplicates before shipping.
Hobby Collection Counts for LEGO, Trading Cards & Models
Mark 1-3 example pieces in the Examples setting — one per piece type you're counting — then run the count. Review the result markers and correct the tally instead of starting a manual count from zero.
Guides for this tool
- A Shelf Can Look Full While the Products Customers Want Run LowA full-looking shelf can hide gaps in the products people want. Explore Pixoate visible-object counts and the context needed for a useful stock review.
- How to Count Shop Inventory from Shelf PhotosCount visible shelf stock, review object markers and export a tally. Learn how to handle hidden items, mixed products and inventory discrepancies.
Watch each transformation land
Every photo crosses the slash untouched and comes out the other side finished.
