Pool chlorine levels chart: FC, TC & CC targets
Combined chlorine (CC) causes pool smell and irritation. Keep CC below 0.5 ppm regardless of CYA.
Normal pool free chlorine (FC) is 2–4 ppm — but only when cyanuric acid (CYA) is low or absent. Every threshold shifts as CYA rises: at CYA 80, 8 ppm FC is squarely in the target range and safe to swim in. The charts on this page start with the no-CYA baseline, then cover CYA-adjusted targets that apply to most real outdoor pools. Combined chlorine (CC) should stay below 0.5 ppm regardless of CYA.
Free chlorine (FC) levels — baseline (no CYA)
Free chlorine is the active sanitizer in your pool — the chlorine that's available to kill bacteria and algae. This is the most important number on your test. The table below applies to pools with little or no cyanuric acid (CYA under 20 ppm) — a freshly filled pool, an indoor pool, or one without any stabilizer added. If your pool has CYA, use the FC/CYA table further down instead.
| FC Level (ppm) | Status | Action |
|---|---|---|
| 0 | No sanitizer | Add chlorine immediately. Your pool has no protection against bacteria or algae |
| 0.1 – 0.9 | Dangerously low | Add chlorine now. Water is not safe for swimming |
| 1.0 – 1.9 | Low | Acceptable short-term, but raise to 2+ ppm soon |
| 2.0 – 4.0 | Ideal | No action needed. This is your target range |
| 4.1 – 7.9 | High | Let it drop naturally. Avoid swimming above 5 ppm (at low CYA — threshold rises with CYA; see table below) |
| 8.0+ | Too high | Do not swim at low CYA. Wait for FC to drop to a safe level. At CYA 50+, safe FC is higher — check the FC/CYA table below before acting |
CDC recommended levels
The CDC recommends a free chlorine concentration of at least 1 ppm in pools (at least 3 ppm in hot tubs and spas) with a pH of 7.2–7.8. That 1 ppm figure is a bare public-health minimum for water without stabilizer — not a target. In a real backyard pool with CYA, you need considerably more than 1 ppm to keep that chlorine active, which is what the FC/CYA chart below accounts for.
How CYA changes your FC target
Most outdoor pools contain cyanuric acid (CYA) — either from stabilized chlorine tablets or direct CYA addition. Once CYA is present, the baseline table above no longer applies. Your safe FC minimum scales with CYA: at CYA 30 the minimum is about 2.25 ppm; at CYA 50 it's about 4 ppm; at CYA 80 it's about 6 ppm. Saltwater/SWG pools use a lower ratio (CYA × 5%) because the salt cell continuously replenishes consumed chlorine.
For the full chart with exact minimums, target ranges, and shock levels at every CYA value — including a live calculator — see the FC/CYA chart →
Know your CYA-based FC target? Enter your pool volume, current FC, and target — get the exact ounces of liquid chlorine to add.
Use the calculator →Combined chlorine (CC) levels
Combined chlorine is chlorine that's already reacted with contaminants — it's spent and no longer sanitizing. You calculate it by subtracting FC from TC.
| CC Level (ppm) | Status | Action |
|---|---|---|
| 0 – 0.2 | Excellent | No action needed |
| 0.2 – 0.5 | Normal | Acceptable. Monitor on next test |
| 0.5 – 1.0 | Elevated | Consider shocking soon if this persists |
| 1.0+ | High | Shock the pool. Chloramines are building up |
High combined chlorine is what causes "that pool smell." It also irritates eyes and skin. If CC stays above 0.5 ppm across multiple tests, it's time to shock.
Total chlorine (TC) levels
Total chlorine is simply FC + CC. On its own, TC doesn't tell you much — what matters is how close it is to your free chlorine reading.
| Scenario | What It Means | Action |
|---|---|---|
| TC equals FC | No combined chlorine. All your chlorine is active | Nothing — this is perfect |
| TC slightly above FC | Small amount of CC. Normal after heavy use | Monitor. Shock if it persists |
| TC much higher than FC | High CC. Chloramines are building up | Shock immediately |
When to test chlorine
- Routine: 2–3 times per week during swim season
- After heavy use: Pool parties, lots of swimmers, heavy rain
- After shocking: Test the next day to confirm FC has dropped to safe levels. Pool still cloudy after shocking?
- After adding chemicals: Wait at least 30 minutes with the pump running, then retest
- Time of day: Morning gives the most accurate baseline — UV destroys chlorine throughout the day. Full testing schedule →
Frequently asked questions
What is the normal (ideal) chlorine level for a pool?
With little or no CYA, 2 to 4 ppm free chlorine is the target and combined chlorine should stay below 0.5 ppm. Once CYA is present — as it is in most outdoor pools — those thresholds rise with your stabilizer level. See the FC/CYA chart for exact targets at every CYA level.
What chlorine level is too high or too low for a pool?
Too low: Without CYA, below 2 ppm is under-sanitized and below 1 ppm is unsafe to swim in. With CYA present, "too low" rises with your stabilizer level — always check FC against your CYA, not as a standalone number.
Too high: Without CYA, above 5 ppm is uncomfortable and above 8 ppm you should wait before swimming. With higher CYA, the safe upper limit is proportionally higher. Combined chlorine (CC) above 0.5 ppm means chloramines are building up regardless of FC level — that's usually the bigger problem.
What chlorine level is safe to swim in?
At low CYA, water is safe to swim in from about 1 up to 5 ppm free chlorine, with 2–4 ppm ideal. Below 1 ppm is unsafe — the water is under-sanitized. Most authorities consider swimming acceptable up to roughly 10 ppm FC; above that, wait for it to drop. With CYA present the whole safe band shifts up: at CYA 80, 8 ppm is comfortably within range, and 3 ppm is actually unsafe-low. This is why "is 8 ppm chlorine safe?" has no single answer — it depends entirely on your CYA. Combined chlorine (CC) above 0.5 ppm is a separate problem regardless of how safe your FC looks.
What is the chlorine level for a saltwater pool?
Saltwater pools target the same free chlorine range as traditional chlorine pools — 2 to 4 ppm in low-CYA water. But salt water generators typically run with CYA at 60 to 80 ppm to protect the generated chlorine from sunlight, which pushes the FC target up to 4 to 6 ppm.
The chlorine itself behaves identically; only the source (salt cell vs liquid or tablets) is different. See saltwater vs chlorine pools for the broader comparison.
Common chlorine problems
Why is total chlorine higher than free chlorine?
When TC is noticeably higher than FC, it means combined chlorine (chloramines) are building up in your water. Combined chlorine is spent — it's already reacted with sweat, urine, sunscreen, or other organics and is no longer sanitizing.
A small gap (0.2 ppm or less) is normal. But if TC is 0.5 ppm or more above FC, chloramines are accumulating and you need to shock. Superchlorination breaks apart chloramines and resets your water. See Free Chlorine vs Total Chlorine for the full breakdown.
Why is my free chlorine low?
Free chlorine drops for a handful of predictable reasons:
- Sunlight without CYA: UV radiation destroys unprotected chlorine in hours. If your CYA is too low, FC won't hold
- CYA too high: Paradoxically, excess stabilizer locks up chlorine and makes it ineffective — your test reads "low" because less FC is available to sanitize
- Algae growth: Even an early bloom you can't see yet will consume chlorine rapidly. If FC drops faster than expected, check for signs of algae
- Heavy bather load: Swimmers introduce organics that react with and consume FC
- Chloramine buildup: If CC is high, some of your chlorine supply is being converted to useless combined chlorine instead of staying active
The fix depends on the cause. Start by testing CYA alongside FC — the FC/CYA chart tells you whether your FC is truly low or just appears low for your stabilizer level. If you need to raise it, see How to Raise Pool Chlorine Safely.
Why does my pool smell like chlorine?
A strong "chlorine smell" almost never means there's too much chlorine. It means there's too much combined chlorine. Chloramines — the byproduct of chlorine reacting with nitrogen-based contaminants — are what produce that harsh chemical odor and irritate eyes and skin.
The fix is counterintuitive: add more chlorine. Shocking the pool to breakpoint chlorination destroys chloramines and eliminates the smell. If CC is above 0.5 ppm on your test, that confirms the diagnosis. A properly chlorinated pool with low CC should have almost no smell at all.
Do pool chlorine levels change with water temperature?
Yes — warmer water demands more chlorine. Higher temperatures speed up bacteria and algae growth, increase the rate of chemical reactions that consume FC, and accelerate chlorine off-gassing. What's sufficient at 70°F may not be enough at 90°F.
As a rule of thumb: if your water temperature climbs above 84°F (29°C), test FC more frequently — daily during heat waves — and be ready to dose more often. The FC/CYA targets in the table above apply at typical pool temperatures; in very warm water, staying toward the top of your target range is safer than the bottom.
How do I raise pool chlorine levels quickly?
The fastest way to raise FC is liquid chlorine (sodium hypochlorite, 10–12.5%). It dissolves instantly, raises FC within minutes of adding with the pump running, and doesn't add CYA — so it won't push your stabilizer higher over time.
To calculate how much to add: you need your pool volume, current FC, and target FC. As a rough guide, 1 fl oz of 12.5% liquid chlorine raises FC by roughly 1 ppm per 1,000 gallons. For a 15,000-gallon pool that needs FC raised from 1 to 4 ppm, that's about 45 fl oz (just under 1.5 quarts). See the full chlorine dosing guide for exact amounts by pool size and chlorine type, or use the free chlorine dose calculator to get the exact number.
Track your chlorine levels over time
PoolChem Tracker logs FC, TC, and CC together, calculates dynamic chlorine targets based on your CYA level, and shows trends so you catch problems early.
Pool Chlorine Series
- Pool Chlorine Levels Chart
- FC/CYA Chart — how much chlorine you need
- Free Chlorine vs Total Chlorine
- What Causes High Combined Chlorine
- Pool chlorine too low? Causes & fixes
- How to raise pool chlorine safely
- Why won't chlorine stay in my pool?
- Liquid chlorine vs tablets
- Does liquid chlorine raise CYA?
Related reading
- Does Liquid Chlorine Raise CYA? — common myth, clear answer
- Baking Soda vs Soda Ash — adjusting pH and alkalinity once chlorine is dialed in
- Pool Chemistry for Beginners — chlorine in context of the 5 key numbers
- Why Is My Pool Water Cloudy? — low FC is the #1 cause of cloudy water
- Free Chlorine Dose Calculator — enter pool size, current FC, and target FC for exact amounts
- All 18 free pool chemistry calculators — dose, shock, pH, alkalinity, CYA, and more