Pool chlorine dosage calculator
Raising 10,000 US gallons from 1 to 3 ppm with 10% liquid bleach takes 25.6 fl oz, or 1.668 lb of product. Enter the pool volume, both chlorine readings and the label strength, and dose without guessing. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Volume
- 10,000
- Current free-chlorine
- 1
- Target fc
- 3
- Product strength
- 10
- Volume unit
- US_gal
- Fc unit
- ppm
- Strength unit
- percent
- Delta ppm
- 2
Keeping free chlorine in the safe residual range starts with four numbers you can read from a test kit and a product label: pool volume in US gallons, the current free-chlorine reading in parts per million, the target free-chlorine residual you want after dosing, and the available-chlorine strength printed on liquid bleach, calcium hypochlorite, or trichlor packaging. This pool chlorine dosage calculator converts those inputs into the product mass and liquid-equivalent volume to add, using the same closed-form mass balance pool stores and service charts publish for one-part-per-million raises. Use the result for daily maintenance tops, shock planning inputs, bag and jug shopping, and written work orders where under-dosing leaves water unsafe and over-dosing wastes chemical and irritates swimmers.
How chlorine product dose is computed from volume and free chlorine
Start from the identity used on every US pool service chart: one part per million is one pound of pure available chlorine per one million pounds of water. With water at eight point three four pounds per US gallon, the pure chlorine mass in pounds equals pool gallons times the free-chlorine increase in parts per million times eight point three four divided by one million. The product you buy is only partially available chlorine, so divide that pure mass by the strength fraction on the label.
Algebraically, dose in pounds equals volume times delta parts per million times eight point three four divided by one million times product strength over one hundred, which is identical to volume times delta times eight point three four divided by ten thousand times the percentage number. A classic check is ten thousand gallons, a one part per million raise, and ten percent liquid sodium hypochlorite: zero point one gallons of product, or twelve point eight fluid ounces, matching consumer bleach charts.
Another check is twenty thousand gallons, a two part per million raise, and sixty-five percent calcium hypochlorite: pure chlorine mass is about zero point three three three six pounds and product mass is about zero point five one three pounds. The pipeline is deterministic floating-point arithmetic with no random seeds, no wall-clock timestamps, and no network calls. Volume must be strictly positive; free-chlorine levels must be non-negative; product strength must be greater than zero and at most one hundred.
What you can do with it
Daily free-chlorine top-up
Read the test kit, set target residual, pick the jug or bag strength, and measure the exact fluid ounces or pounds of product to restore a safe free-chlorine level.
Retail bag and jug shopping
Help DIY buyers turn pool volume and product label percent into a purchase quantity without over-buying bleach or cal-hypo.
FAQ
What units should I use?
Volume is US gallons. Product strength is available chlorine percent on the label (for example 10 for 10% liquid).
What does it cost?
The browser tool is free and runs locally.
How much bleach raises chlorine by 1 ppm in a 10,000 gallon pool?
With 10% liquid bleach you need 0.1 gallon, which is 12.8 fl oz. That matches the classic consumer bleach charts, because one part per million is one pound of pure chlorine per million pounds of water.
What happens if my target chlorine level is below the current reading?
The calculator only works out a dose to raise the level, so a target below the current reading is refused instead of giving a negative dose. If both readings are equal, the dose is simply zero.
What strength should I enter for my chlorine product?
Enter the available chlorine percentage printed on the label: 10 for 10% liquid bleach, 65 for calcium hypochlorite or 90 for trichlor. Weaker products need proportionally more weight for the same raise.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/home/pool-chlorine \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"volume":10000,"current_fc":1,"target_fc":3,"product_strength":10}'const res = await fetch("https://api.kit.forhosting.com/home/pool-chlorine", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"volume": 10000,
"current_fc": 1,
"target_fc": 3,
"product_strength": 10
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/home/pool-chlorine",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"volume": 10000,
"current_fc": 1,
"target_fc": 3,
"product_strength": 10
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/home/pool-chlorine", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"volume":10000,"current_fc":1,"target_fc":3,"product_strength":10}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"volume":10000,"current_fc":1,"target_fc":3,"product_strength":10}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/home/pool-chlorine", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"volume": 10000,
"current_fc": 1,
"target_fc": 3,
"product_strength": 10
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "home.pool_chlorine",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
When the target residual sits below the current reading the request fails with a clear invalid_input message instead of inventing a negative dose or a dechlorination path you did not ask for.
How chlorine product dose is computed from volume and free chlorine
The calculator returns pure_chlorine_lbs, dose_lbs, a dose_lbs_check from the compact form, dose_gallons and dose_fl_oz for liquid-equivalent volume under the density-approximately-water approximation, plus delta_ppm and strength_fraction for audits. A target free-chlorine value below the current level is always invalid_input because this tool only computes a raise dose.
What you send and what you get back
Non-positive volume, negative free-chlorine values, product strength of zero or near zero, negative strength, and strength above one hundred are rejected the same way. Equal current and target levels succeed with a zero dose so automation can no-op cleanly. Send four required finite numbers: volume for pool water in US gallons, current_fc for the present free-chlorine residual in parts per million, target_fc for the residual you want after dosing in the same units, and product_strength for the available chlorine percentage on the product label such as ten for ten percent liquid bleach or sixty-five for calcium hypochlorite. Missing required fields, non-numeric strings, NaN, and Infinity fail with invalid_input and are not charged. When target_fc is strictly less than current_fc the request fails with a message that the target is below the current level, so clients correct the readings or choose a dechlorination workflow instead of receiving a negative dose. On success the response echoes cleaned inputs, sets volume_unit to US_gal, fc_unit to ppm, and strength_unit to percent, returns delta_ppm, strength_fraction, pure_chlorine_lbs, dose_lbs, dose_lbs_check, dose_gallons, dose_fl_oz, water_lb_per_gal, a unit_note describing the conventions, and a short formula string for documentation. Pricing for successful API calls is the published base of $0.002 per item; validation failures do not consume prepaid balance.
Where pool chlorine dosage calculators show up in real work
Homeowners following a weekly free-chlorine program need a trustworthy product volume before opening jugs or bags, especially when a single under-dose leaves water unsafe for swimming and over-dose wastes chemical while raising combined chlorine risk. Garden centres and e-commerce product pages often embed a chlorine helper next to liquid bleach and granular hypochlorite SKUs so shoppers convert pool size and test-kit readings into the fluid ounces or pounds they should buy. If you later need cyanuric acid demand curves, breakpoint chlorination time series, salt-system output estimates, pH and alkalinity balancing, or metric-litre pool volumes with country-specific product densities, treat those as separate search intents and landings rather than overloading this pool chlorine dosage calculator page. Pool service crews write material take-offs from measured or plate-volume gallons and a published residual target; a single deterministic endpoint reduces spreadsheet drift between the dispatcher and the technician who measures bleach or scoops cal-hypo at the curb. Property managers with multiple community pools feed each basin’s volume, current residual, target residual, and product strength through the API and attach dose_lbs or dose_gallons to work orders so inventory drawdowns stay intentional. Because this capability is a pure parse engine, API pricing is the published base of $0.002 per successful item and failed validation does not consume balance.
Integration use cases
Service-route material lists
Convert each stop’s pool gallons, current FC, target FC, and product strength into dose_lbs or dose_gallons so vans stock the right chemical mass.
Technical questions
How is pool chlorine dose calculated?
Pure chlorine mass in pounds is volume_gallons × (target_fc − current_fc) × 8.34 / 1,000,000. Divide by product_strength/100 to get product pounds; liquid gallons assume density ≈ water.
What happens if the target free chlorine is below the current level?
The request fails with invalid_input. This calculator only computes a raise dose; it will not return a negative quantity or a dechlorination path.
Does dose_gallons work for granular products?
dose_lbs is the primary mass for solids such as cal-hypo or trichlor. dose_gallons and dose_fl_oz are liquid-equivalent volumes assuming density near water and are most natural for sodium hypochlorite solutions.