Tallypic

Take or choose a photo to countDrop a photo to count

Count bacterial colonies in a photo

Count bacterial colonies free online from a photo of the plate. Check one marker per colony, fix merged or missed ones and save the count with the date.

How to photograph bacterial colonies for counting ↓

What are you counting?135 types

For an accurate count

  • Shoot from directly aboveor straight at pipe, rebar and log ends.
  • Spread items in one layerPiles and overlaps cause misses.
  • Use a contrasting backgroundand avoid glare, shadows and blur.

How to photograph bacterial colonies for counting

  1. 1

    Photograph the plate from above

    Take the lid off or wipe away condensation, then hold the camera straight over the dish so the whole plate fits in the frame.

  2. 2

    Use a dark, even background

    Set the plate on black card or a dark mat and avoid glare from ceiling lights on the dish. Pale colonies need contrast against the agar.

  3. 3

    Check the rim, writing and merged colonies

    Zoom into the edge of the plate, marker pen on the dish and colonies that have grown together. Remove marks on bubbles or writing and add any small colonies that were missed.

A plate on a dark background makes pale colonies stand out from the agar.

Photo example

A plate on a dark background makes pale colonies stand out from the agar.

The tool's sample opens saved example markers; uploading your own photo runs a new count.

63 bacterial colonies are marked in the tool's sample photo.

When to count bacterial colonies from a photo

Microbiology, food and water testing labs and teaching labs count the colonies on each plate after incubation to work out CFU per millilitre or gram. Dotting colonies with a pen and clicking a tally counter is slow, and it's easy to lose your place. Photograph each plate, check one marker per colony and save the marked image, which shows the total and the date, with your plate records.

Questions about counting bacterial colonies

Is there a colony counter app for my phone?

You don't need to install one. Tallypic works in your phone's browser: open this page, tap Take a photo and shoot the plate from directly above. Check the markers, then save the marked image to your phone. There are free counts every day and no signup.

Can it calculate CFU/mL?

No. It gives the number of colonies on one plate. Pick plates within the countable range your method specifies, then apply the dilution factor and the volume plated yourself.

What if the colonies are tiny or crowded?

Choose Bacterial colonies (high precision) in the object picker and upload the same photo again. Whichever model you use, zoom into dense areas, remove duplicate markers and add any that were missed.

More counting guides

Steel pipesSteel pipesFace the pipe endsOpen counter & guide RebarRebarPhotograph the cut endsOpen counter & guide VialsVialsShow one visible layerOpen counter & guide CapsulesCapsulesSeparate touching capsulesOpen counter & guide TabletsTabletsMake a single layerOpen counter & guide Shrimp larvaeShrimp larvaeUse a shallow white basinOpen counter & guide SeedsSeedsSpread the seeds in one layerOpen counter & guide EggsEggsShoot from directly aboveOpen counter & guide LogsLogsFace the cut endsOpen counter & guide ScrewsScrewsSpread them outOpen counter & guide CoinsCoinsLay the coins flat in one layerOpen counter & guide PVC pipesPVC pipesShoot the open ends straight onOpen counter & guide