How to Dilute Sodium Hypochlorite | Making 0.02%, 0.05% and 0.1% Solutions, and ppm
When you make a disinfectant from chlorine bleach, being told to “dilute to 0.05%” or “make it 200 ppm” still leaves you wondering how many capfuls go into a plastic bottle. Household bleach varies from about 5% to about 6% depending on the product, and the amount changes with it. This guide covers how % relates to ppm, when to use 0.02%, 0.05% and 0.1%, dilution tables for 6% and 5% bleach, step-by-step instructions for a plastic bottle, how to handle the diluted solution, and what you must never mix it with.
0.05% is 500 ppm | Converting between % and ppm
ppm (parts per million) expresses how many parts per million, and 1% = 10,000 ppm. Multiply a percentage by 10,000 to get ppm, and divide ppm by 10,000 to get %. Disinfectant strengths are written in % in some sources and in ppm in others, so first put them in the same unit.
| % | ppm | Main uses |
|---|---|---|
| 0.02% | 200 ppm | Soaking dishes, chopping boards and cloths; everyday disinfection of door handles and similar |
| 0.05% | 500 ppm | Wiping surfaces that hands touch often |
| 0.1% | 1000 ppm | Disinfecting floors and objects soiled with vomit or faeces |
Sodium hypochlorite, the active ingredient in household chlorine bleach (for kitchen or laundry use), is sold at about 5 to 6% depending on the product. The safest approach is to check the strength on the label or the manufacturer’s website before you calculate.
Dilution tables for 6% and 5% bleach
The dilution factor is “stock concentration ÷ target concentration”. With 6% bleach, 0.02% is 300 times, 0.05% is 120 times and 0.1% is 60 times. The amount of bleach is “final volume ÷ dilution factor”.
| From 6% bleach | Factor | 500 mL | 1 L | 2 L |
|---|---|---|---|---|
| 0.02% (200 ppm) | 300× | about 1.7 mL | about 3.3 mL | about 6.7 mL |
| 0.05% (500 ppm) | 120× | about 4.2 mL | about 8.3 mL | about 16.7 mL |
| 0.1% (1000 ppm) | 60× | about 8.3 mL | about 16.7 mL | about 33.3 mL |
| From 5% bleach | Factor | 500 mL | 1 L | 2 L |
|---|---|---|---|---|
| 0.02% (200 ppm) | 250× | 2 mL | 4 mL | 8 mL |
| 0.05% (500 ppm) | 100× | 5 mL | 10 mL | 20 mL |
| 0.1% (1000 ppm) | 50× | 10 mL | 20 mL | 40 mL |
5% bleach gives round numbers, but 6% bleach leaves fractions. A bottle cap holds about 5 mL, so making 500 mL of 0.05% from 6% bleach takes about 4.2 mL (about 0.8 of a cap), and 0.1% takes about 8.3 mL (about 1.7 caps). The dilution factor calculation itself is explained in How to Calculate Dilution Ratios.
Making disinfectant in a plastic bottle, step by step
- 1
Get ready
Open a window for ventilation and put on rubber gloves. Have an empty 500 mL or 2 L plastic bottle and a cap or measuring spoon for measuring (kept separate from the ones used for food).
- 2
Fill the bottle about halfway with water
Put tap water into the bottle until it is about half full. If you add the bleach first, the water you pour in afterwards tends to make it foam and splash.
- 3
Measure and add the bleach
Measure the amount of bleach from the table or the tool and add it. For 500 mL of 0.05% from 6% bleach that is about 4.2 mL; for 2 L it is about 16.7 mL (about 3.3 caps).
- 4
Top up to the full volume
For 500 mL, add water up to the 500 mL line (around the bottle’s shoulder), close the cap and mix gently.
- 5
Label the contents
So nobody drinks it by mistake, write “Disinfectant (0.05%), not for drinking” and the date on the bottle, and keep it out of children’s reach.
Whether you add water to a “full 500 mL” or to a “finished 500 mL” changes the concentration slightly, but with a large factor such as 120 the difference is around 1%. Putting one capful (5 mL) of 6% bleach into a 500 mL bottle and filling it gives about 0.06% (600 ppm). Enter the amounts of bleach and water you used in the tool’s “Check a solution’s concentration” and it works out the actual concentration and ppm.
How to use it and how to handle the diluted solution
- For wiping, soak a cloth or paper towel in the diluted solution, wipe, leave it for about 10 minutes and then wipe again with water. Metal corrodes easily, so don’t skip the water wipe
- For soaking, leave dishes, cloths and the like in the 0.02% solution for a few minutes up to about 10 minutes, then rinse well
- Don’t use it to disinfect hands or skin. Wash hands with soap and running water
- The diluted solution loses effectiveness over time, so make it fresh each time and throw away what is left. The bleach itself also weakens as it ages
- Coloured or patterned fabrics, wood, aluminium and similar materials can fade or be damaged, so take care
- When cleaning up vomit, wear disposable gloves, a mask and an apron, gently wipe it up with paper from the outside inwards, then disinfect with the 0.1% solution, and seal everything you used in a plastic bag before throwing it away
For how to make the right strength when you want to disinfect with alcohol, see How to Dilute Anhydrous Ethanol to 70%.
FAQ
- How many mL of bleach do I put in 500 mL to make a 0.05% disinfectant?
- If the bleach is 6%, the factor is 120, so about 4.2 mL (about 0.8 of a cap); if it is 5%, the factor is 100, so 5 mL (one cap). Check the product’s strength before you calculate.
- What percentage is 200 ppm?
- 1% = 10,000 ppm, so 200 ppm is 0.02%. 500 ppm is 0.05% and 1000 ppm is 0.1%.
- How do I make the 0.1% solution used for disinfecting vomit?
- Dilute 6% bleach 60 times: about 8.3 mL for 500 mL, or about 16.7 mL for 1 L. With 5% bleach it is 50 times, so 10 mL (two caps) for 500 mL. Ventilate the room and wear gloves while you work.
- How long can I keep the disinfectant I made?
- The diluted solution loses effectiveness over time, so the rule is to make it each time you use it. Light and heat also speed up its breakdown, so don’t make it in advance, and discard any that is left over.
- What concentration do I get from one capful in a 500 mL bottle?
- A capful is about 5 mL, so with 6% bleach you get about 0.06% (600 ppm), and with 5% bleach about 0.05% (500 ppm).
Tools in this article
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