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Bleach Dilution Calculator

Ready to calculate
CDC/EPA Compliant.
Any Stock %.
Bidirectional.
100% Free.
No Data Stored.

How it Works

01Enter Stock %

Provide starting bleach concentration.

02Set Target ppm

Match target to your application standard.

03Final Volume

How much diluted solution you need.

04Mix Volumes

Returns mL of stock and water to combine.

What is a Bleach Dilution Calculator?

The Bleach Dilution Calculator tells you exactly how much concentrated household or industrial bleach (sodium hypochlorite, NaClO) to mix with water to reach a target ppm chlorine concentration in a specific final volume. CDC, FDA, and EPA all specify dilution targets in ppm or % free chlorine — but bottle labels typically list percent NaClO (5.25%, 6%, 8.25%, 12.5%), creating endless room for math errors.


Inputs: stock bleach concentration (% NaClO), target free chlorine (ppm), and final volume (L, gal, oz). Output: exact bleach volume + water volume to mix. Standard reference targets: 200 ppm sanitizer (food contact surfaces), 500 ppm disinfectant (countertops, gen. cleaning), 5,000 ppm disinfectant (CDC blood/biohazard).

How to Use the Calculator

Enter stock concentration (% NaClO): 5.25–6% (typical household), 8.25% (concentrated household), 10–12.5% (industrial/pool).
Enter target ppm: 50, 200, 500, 1000, 2500, 5000 — pick from CDC/EPA reference levels or enter custom.
Enter final volume: total mixed solution wanted.
Calculate: Returns mL bleach + mL water. Cross-check with the use-case reference table.

The Math Behind It

Standard dilution math (C₁V₁ = C₂V₂):


Bleach volume = (target ppm × final volume) / (stock % × 10,000)


The "10,000" converts percent (e.g., 6) to ppm (60,000). Example: 200 ppm in 1 L from 6% bleach: V = (200 × 1000 mL) / (6 × 10,000) = 3.3 mL bleach in (1000 − 3.3) ≈ 997 mL water. Bleach loses 1–2% strength per month after opening; replace stock every 90 days for accurate dilutions.

Real-World Example

Worked Example

500 ppm general disinfectant from 5.25% household bleach, 1 gallon (3,785 mL) final:

  • Bleach = (500 × 3785) / (5.25 × 10,000) = 36 mL bleach (~2.4 tbsp)
  • Water: 3785 − 36 = 3,749 mL water
  • Mix in a labeled spray bottle; replace solution every 24 hours (free chlorine degrades).

Who Uses It

1
🍽 Restaurants / Food Service: 200 ppm sanitizer for 3-compartment sinks (FDA Food Code).
2
🏥 Healthcare / Daycare: 500–5000 ppm disinfectant for surface decontamination.
3
🏊 Pool / Spa: Maintain 1–4 ppm free chlorine; shock at 10–30 ppm.
4
🌱 Hydroponic / Greenhouse: 50 ppm root-zone sanitizer; 200 ppm tool dip.
5
🐔 Poultry / Livestock: 5–20 ppm drinking water sanitization.
6
🏠 Mold Remediation: 5,000 ppm (1:10 dilution) for non-porous surfaces.

Technical Reference

Reference dilution targets:

  • 50 ppm: Hydroponic root zone, drinking water shock
  • 100–200 ppm: Food-contact surface sanitizer (FDA Food Code, no rinse)
  • 500 ppm: General disinfectant (countertops, bathrooms)
  • 1,000 ppm: Healthcare hard-surface disinfection
  • 2,500 ppm: CDC mold/mildew (non-porous)
  • 5,000 ppm (1:10): CDC blood/body fluid disinfection
  • 10,000 ppm: Severe biohazard, industrial use

NEVER mix bleach with: ammonia (chloramine gas), acids/vinegar (chlorine gas), hydrogen peroxide, alcohol. Use in ventilated area; wear eye protection for >500 ppm.

Key Takeaways

Free chlorine concentration matters more than NaClO percentage. Always match target ppm to the regulatory standard for your application: 200 ppm sanitizer for food contact, 500 ppm general disinfection, 5,000 ppm for biohazards. Mixed bleach solutions degrade within 24 hours — make fresh daily.

Frequently Asked Questions

How long does diluted bleach last?
Free chlorine in dilute solution degrades within 24 hours, faster in light or warm conditions. Make fresh daily for sanitizer and disinfectant use. Stock concentrate loses ~1–2% strength per month after opening; ~50% over a year unopened.
What's the difference between sanitizer and disinfectant?
Sanitizer (50–200 ppm): reduces bacteria by 99.9% on food-contact surfaces; no rinse needed. Disinfectant (500–5000 ppm): kills 99.99%+ of bacteria, viruses, fungi on hard surfaces; requires contact time (1–10 min). Sterilizer: kills all microbes including spores; not achieved by bleach in normal use.
Can I use scented bleach?
For laundry yes; for food-contact sanitization NO. EPA only registers unscented bleach for surface disinfection. Scented bleach contains surfactants that leave residue.
Why does my bleach solution smell stronger over time?
You're smelling chlorine gas off-gassing as the solution degrades. Cap tightly and use within 24 hours. Strong chlorine smell + headache = ventilation problem.
Is bleach safe on stainless steel?
Short contact (≤10 min) yes; prolonged contact (overnight) can pit the surface. Always rinse with clean water after disinfection contact time.
What about pool shock vs bottled bleach?
Pool shock is calcium hypochlorite (Ca(OCl)₂, 65–75% available chlorine) — granular, more concentrated. Bottled bleach is sodium hypochlorite (NaClO, 5.25–12.5%). Both deliver free chlorine but use different math; this calculator is for liquid NaClO.

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Disclaimer

Bleach is corrosive. Wear gloves and eye protection. Never mix with ammonia, acids, peroxide, or alcohol — toxic gas hazard. Use in ventilated areas. Free chlorine degrades within 24 hours of dilution; mix fresh daily. For regulated environments (food service, healthcare), follow specific agency guidelines (FDA Food Code, CDC, OSHA).