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Calculator

Serial Dilution Calculator

Calculate per-tube concentrations for a serial dilution series.

Microbiology #cfu #microbiology #serial-dilution #dilution-series
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Formula & Clinical Notes

Formula

Tube n = Initial concentration / Dilution factorⁿ

Clinical Notes

Each tube reduces the concentration by the dilution factor: tube n = initial / factorⁿ. For a 10-fold serial dilution of a 10⁸ CFU/mL culture, tubes contain 10⁷, 10⁶, 10⁵, 10⁴, 10³ and 10² CFU/mL. Ideal plates come from tubes giving 25–250 colonies.

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