# Plaque Forming Units Calculator (PFU/mL)

Compute PFU/mL titer from plaque counts, dilution factor, and plated volume, with multi-plate statistics and 30–300 counting-range warnings.

> Canonical page: https://elysiatools.com/en/tools/plaque-forming-unit

- **Category:** Health

- **Keywords:** pfu calculator, pfu/ml, plaque assay, plaque count, bacteriophage titer, serial dilution, double layer agar, viral titer, plaque forming units, phage enumeration, microbiology, lab calculator

## Overview

The Plaque Forming Units Calculator converts plaque-assay counts into PFU/mL titer. Enter one or more plate counts, the fold-dilution of the plated sample, and the volume plated in microliters to obtain mean titer, multi-plate statistics, and 30–300 counting-range warnings.

## Inputs

- **Plaque counts per plate** (textarea): Plaque counts from each plate, separated by commas, spaces, or new lines.
- **Dilution factor plated** (number): Fold-dilution of the plated sample relative to the original (10⁻⁶ → 1000000).
- **Plated volume (µL)** (number): Volume of the diluted sample mixed into the top agar (100 µL is typical).

## When to use

- After counting plaques on double-layer agar plates from a serial dilution.
- When averaging replicate plates at the same dilution to report a stock titer.
- When checking whether mean plaque counts fall in the reliable 30–300 range before calculating PFU/mL.

## How it works

- Enter plaque counts from each plate, separated by commas, spaces, or new lines.
- Enter the fold-dilution of the plated sample (for example 1000000 for a 10⁻⁶ dilution) and the plated volume in µL (100 µL is typical).
- The tool averages the counts, converts plated volume to mL, and computes PFU/mL = mean plaques × dilution factor ÷ volume in mL.
- It reports standard deviation, CV%, and warns if the mean count is below 30 or above 300.

## Use cases

- Bacteriophage enumeration after serial dilution and double-layer agar plating.
- Viral plaque-assay titer calculations in a teaching or research lab.
- Checking replicate-plate agreement and counting-range validity before reporting PFU/mL.

## Frequently asked questions

### How is PFU/mL calculated?

PFU/mL = mean plaque count × dilution factor ÷ plated volume in mL. Volume entered in µL is divided by 1000.

### Can I use counts from more than one plate?

Yes. List one number per plate. The calculator uses the mean and reports SD and CV%.

### What do the 30–300 warnings mean?

A mean below 30 is statistically less reliable; a mean above 300 often means plaques merged and the titer is underestimated. Use a less or more dilute sample.

### What value do I enter for dilution factor?

The fold-dilution of the sample that was actually plated relative to the original stock. A 10⁻⁶ dilution is entered as 1000000.

### What plated volume should I use?

The volume of diluted sample mixed into the top agar, in microliters. 100 µL is a common default.

## Related tools

- [Extended BMR Calculator (Mifflin / Schofield Multi-Formula Comparison)](https://elysiatools.com/en/tools/basal-metabolic-rate-ext): Compare Mifflin-St Jeor, original and revised Harris-Benedict, Schofield (FAO/WHO/UNU), and Katch-McArdle BMR equations side by side with mean and spread in kcal/day. Not medical advice.
- [Cell Confluency Estimator (Microscopy Grid Method)](https://elysiatools.com/en/tools/confluency-estimator): Estimate adherent-cell confluency with the grid-count method: confluency% = occupied/total squares × 100 per field, with multi-field mean ± SD and optional time-to-target from the doubling time.
- [Free Water Clearance Calculator](https://elysiatools.com/en/tools/free-water-clearance): Calculate solute-free water clearance (C_H₂O) and electrolyte-free water clearance (eC_H₂O) to differentiate hypo-/hypernatremia. Classic: C_H₂O = V·(1 − U_osm/P_osm); positive = dilute urine excreting free water (diabetes insipidus, polydipsia, water-load recovery), negative = concentrated urine conserving free water (dehydration, SIADH). Electrolyte-free: eC_H₂O = V·(1 − (U_Na + U_K)/P_Na), which better predicts the direction of serum sodium change — a negative eC_H₂O means the urine is electrolyte-free-water-rich and tends to raise serum Na⁺, informing IV fluid choice. Optional Na/K inputs enable the electrolyte-free calculation. Derived from Rose, Shimizu 2002 (Nephron), and NephSIM. Point estimate; interpret with full clinical context. Not medical advice.
- [Mean Arterial Pressure (MAP)](https://elysiatools.com/en/tools/mean-arterial-pressure): Calculate MAP = DBP + (SBP − DBP)/3. Normal 70–100; ≥65 sepsis target; <65 hypoperfusion. Derived from Geddes 1984, SSC 2021, BTF 2017, StatPearls, LITFL. Not medical advice.
- [Mean Platelet Volume (MPV) Analyzer](https://elysiatools.com/en/tools/mean-platelet-volume-analyzer): Analyze Mean Platelet Volume (MPV) in fL, an index of platelet production kinetics. Reference range ≈ 7.5–11.5 fL (lab- and method-dependent). Low MPV (< 7.5 fL, small old platelets) indicates suppressed marrow production (aplastic anemia, chemotherapy/radiation, recent platelet transfusion, iron-deficiency regeneration, Wiskott-Aldrich). High MPV (> 11.5 fL, large young platelets) indicates peripheral destruction with compensatory turnover or macrothrombocytopenia (immune thrombocytopenia ITP, post-splenectomy, myeloproliferative neoplasms, severe sepsis in recovery, Bernard-Soulier / MYH9, megaloblastic anemia; elevated MPV after acute MI marks platelet activation and adverse prognosis). Optionally enter the platelet count to refine the differential: low platelets + high MPV → peripheral destruction; low + low → underproduction; high + low → reactive thrombocytosis; high + high → myeloproliferative neoplasm. Pre-analytical caveat: platelets swell in EDTA over ~2 h raising MPV, and values are method-dependent (impedance > optical > immuno) — compare within the same lab and analyzer. Derived from Bath 1996, Leader 2012, Vagdatli 2010, and MDCalc. Not medical advice.
- [Pulmonary Vascular Resistance Calculator (PVR)](https://elysiatools.com/en/tools/pulmonary-vascular-resistance): Compute PVR = (mPAP − PCWP) / CO in Wood units and dyn·s/cm⁵. Normal < 3 Wood; elevated in pulmonary hypertension. Derived from Grossman 1991, Simonneau 2019, Humbert ESC/ERS 2022, StatPearls, LITFL. Not medical advice.
- [Pulse Pressure Calculator (PP = SBP − DBP)](https://elysiatools.com/en/tools/pulse-pressure-calculator): Calculate PP = SBP − DBP and MAP = DBP + PP/3. Normal ~30–40 mmHg; wide PP → high SV or stiff arteries; narrow PP → low SV. Pulsus paradoxus flags tamponade/asthma/PE. Derived from McDonald's, Franklin 1999, Blacher 1999, StatPearls, LITFL. Not medical advice.
- [Red Cell Distribution Width (RDW) Analyzer](https://elysiatools.com/en/tools/rdw-analyzer): Analyze Red Cell Distribution Width (RDW) with MCV to help differentiate anemias. RDW-CV reference ≈ 11.5–14.5%, RDW-SD ≈ 39–46 fL (lab-dependent). Elevated RDW reflects anisocytosis. Classic Bessman patterns: high RDW + low MCV → iron deficiency anemia (IDA), which raises the RDW early — before MCV/Hb fall; normal RDW + low MCV → thalassemia trait (uniform microcytosis). Other patterns: high RDW + high MCV → megaloblastic anemia (B12/folate), MDS, drugs, hemolysis with reticulocytosis, preleukemia, or mixed populations (combined iron + B12 deficiency, post-transfusion); high RDW + normal MCV → early/mixed nutritional deficiency, dimorphic anemia, marrow recovery; normal RDW + normal MCV → anemia of chronic disease is classically normocytic. Interpret with Hb, ferritin, Hb electrophoresis, and clinical context. Based on Bessman 1983 and Teixeira 2014. Not medical advice.

## Samples

- [Web Image Processing Python Samples](https://elysiatools.com/en/samples/web-image-processing-python): Web Python image processing examples using PIL/Pillow including reading, saving, resizing, and format conversion
- [Android Image Processing Java Samples](https://elysiatools.com/en/samples/android-image-processing-java): Android Java image processing examples including reading/saving images, scaling, and format conversion
- [Android Image Processing Kotlin Samples](https://elysiatools.com/en/samples/android-image-processing-kotlin): Android Kotlin image processing examples including reading/saving images, scaling, and format conversion
- [Web Image Processing Rust Samples](https://elysiatools.com/en/samples/web-image-processing-rust): Web Rust image processing examples including image read/save, scaling, and format conversion