Ammonia Concentration Calculator
Enter a % NH3 concentration to get density, specific gravity, g/L, and molarity — or enter a measured density to solve for concentration. Note: density falls as concentration rises for ammonia, opposite of caustic soda and mineral acids.
Why this curve runs backward
Sanity check first: a bigger percentage always gives a smaller number here. 0% NH₃ (plain water) is 0.9982 g/cm³; 30% NH₃ is about 0.892 g/cm³. If you're coming from the NaOH or HCl calculators on this site, where the density line climbs as concentration climbs, that's the opposite of what you'll see here — and it isn't a bug.
Sodium hydroxide and hydrochloric acid are strong electrolytes: nearly every molecule that dissolves splits into ions, and those ions pull surrounding water molecules into tight hydration shells, packing more mass into the same volume as concentration rises. Ammonia doesn't do that. NH₃ is a small, light molecule that stays overwhelmingly in its molecular form in solution rather than fully ionizing, and it loosens water's own hydrogen-bond network more than it adds compensating mass. The net effect is that the solution's volume grows faster than its mass does as you add more ammonia — so mass ÷ volume, which is density, falls.
This matters beyond trivia. If you're estimating the shipping weight of a full tote or drum from its volume, a 29% aqua-ammonia tote is measurably lighter, gallon for gallon, than a 10% one — the reverse of what you'd assume moving up from a caustic tank. Run the two concentrations through this calculator (or a tank volume calculator if you're working from a partially filled vessel) before you write a number on a bill of lading.
Worked examples
Mixing a 10% degreasing bath
A shop needs to know the density and molarity of a 10% technical ammonia solution to convert a mixing recipe from volume to mass for a bulk tank.
- Concentration
- 10% w/w
- Basis
- 20°C
≈ 0.9575 g/cm³ (SG 0.9592), 5.62 mol/L
Checking an incoming aqua-ammonia delivery
A plant operator dips a hydrometer into a tanker delivery of aqua ammonia for an SCR NOx-control system and reads 0.923 g/cm³ — before accepting the load, they need the % NH₃ to confirm it matches the reagent-grade spec on the order.
- Measured density
- 0.923 g/cm³
- Basis
- 20°C
≈ 19.97% w/w, 10.82 mol/L
How the calculator works
The reference table lists independently measured density values at fixed weight-percent points, all at 20°C. Rather than force one algebraic curve across the full 0–30% range — real solutions don't oblige, and ammonia's is no exception — the calculator brackets your input between the two nearest table rows and interpolates linearly across that short segment. Because the segments are closely spaced, a straight line between neighbors tracks the true (slightly curved, and here downward-sloping) curve closely.
Once density is known, converting to molarity is the same mass balance used on this site's other concentration pages: a liter of solution weighs 1000 × density grams, the % w/w share of that mass is dissolved NH₃, and dividing by ammonia's molar mass (17.031 g/mol) gives moles per liter.
M = 10 × density × wt% / 17.031
Checking the numbers against published references
Interpolating this table at exactly 25.00% NH₃ gives 0.9070 g/cm³ — which lines up with the 0.90–0.91 g/mL density that reagent-grade "25% ammonia solution" carries on safety data sheets from major lab suppliers. At 28%, one of the table's own measured rows reads 0.8980 g/cm³, matching the ≈0.898 specific gravity long quoted on technical 28–30% ammonium hydroxide product sheets — a different figure, from a different kind of source (a commercial spec rather than a lab reference table), landing on the same number. When two independently sourced figures agree at two different concentrations, that's a reasonable basis for trusting the curve in between.
For comparison, the same interpolation method applied to this site's NaOH and HCl tables checks out the same way against their own commercial reference grades — the method doesn't change from compound to compound, only the shape of the curve it's walking.
Where this comes up: cleaning, exhaust treatment, and blueprints
"Aqua ammonia," "ammonia solution," and "ammonium hydroxide" are the same product family at different strengths, and the strengths people actually work with vary widely by industry. Household glass and floor cleaners run 5–10% or less; industrial degreasers and janitorial concentrates land in the 10–15% range diluted from a stronger stock (see dilution math in practice for the general recipe-scaling approach, or the solution dilution calculator for the mass-balance directly); and stationary Selective Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR) systems — the NOx-scrubbing equipment on power plants and industrial boilers — typically inject 19% or 29% reagent-grade ammonia (≈0.9262 g/cm³ and ≈0.8950 g/cm³ by this table, respectively). Checking a bulk storage tank's contents by dip stick works the same way it does for any liquid — see reading tank dip charts and the tank strapping chart calculator — but converting that dipped volume to a mass of NH₃ delivered still runs through this page's density, not a generic water-based chart.
Don't confuse this with Diesel Exhaust Fluid (DEF). DEF, the fluid poured into a separate tank on modern diesel trucks and cars for mobile SCR, is a 32.5% solution of urea in deionized water — no ammonia at all until the catalyst thermally splits the urea apart inside the hot exhaust stream. It's easy to conflate the two because both systems exist to strip NOx and both ultimately react ammonia at a catalyst, but the fluid you buy, store, and dose is chemically different in each case, and DEF's density-vs-concentration behavior has nothing to do with the table on this page.
Before photocopiers and CAD plotters took over, architecture and drafting offices ran drawings through diazo ("whiteprint" or "blueline") reproduction machines, which developed light-exposed diazo-coated paper by passing it through ammonia vapor — typically boiled off a reservoir of 25–30% aqueous ammonia inside the machine. A handful of these machines are still in service today for large-format archival reproduction, and the strong-ammonia stock they run on is exactly the upper end of this table.
Safety: never combine an ammonia-based cleaner with bleach — the reaction releases toxic chloramine vapors. Keep the two off the same rag, bucket, or drain. See the bleach dilution calculator for the same warning from the other side of that mistake.
NH₃ density reference table (20°C)
| Concentration | Density | Specific gravity | g/L | Molarity |
|---|---|---|---|---|
| 0.00% | 0.9982 g/cm³ | 1.0000 | 0.0 g/L | 0.00 mol/L |
| 2.00% | 0.9895 g/cm³ | 0.9913 | 19.8 g/L | 1.16 mol/L |
| 4.00% | 0.9811 g/cm³ | 0.9829 | 39.2 g/L | 2.30 mol/L |
| 6.00% | 0.9730 g/cm³ | 0.9748 | 58.4 g/L | 3.43 mol/L |
| 8.00% | 0.9651 g/cm³ | 0.9668 | 77.2 g/L | 4.53 mol/L |
| 10.00% | 0.9575 g/cm³ | 0.9592 | 95.8 g/L | 5.62 mol/L |
| 12.00% | 0.9501 g/cm³ | 0.9518 | 114.0 g/L | 6.69 mol/L |
| 14.00% | 0.9430 g/cm³ | 0.9447 | 132.0 g/L | 7.75 mol/L |
| 16.00% | 0.9362 g/cm³ | 0.9379 | 149.8 g/L | 8.80 mol/L |
| 18.00% | 0.9295 g/cm³ | 0.9312 | 167.3 g/L | 9.82 mol/L |
| 20.00% | 0.9229 g/cm³ | 0.9246 | 184.6 g/L | 10.84 mol/L |
| 22.00% | 0.9164 g/cm³ | 0.9181 | 201.6 g/L | 11.84 mol/L |
| 24.00% | 0.9101 g/cm³ | 0.9117 | 218.4 g/L | 12.83 mol/L |
| 26.00% | 0.9039 g/cm³ | 0.9055 | 235.0 g/L | 13.80 mol/L |
| 28.00% | 0.8980 g/cm³ | 0.8996 | 251.4 g/L | 14.76 mol/L |
| 30.00% | 0.8920 g/cm³ | 0.8936 | 267.6 g/L | 15.71 mol/L |
Sources: Density–concentration data compiled from standard aqueous ammonia references at 20°C, consistent with the aqueous-ammonia density data reproduced in the CRC Handbook of Chemistry and Physics and Perry's Chemical Engineers' Handbook. 0% anchored to the standard density of water (0.9982 g/cm³ at 20°C). Cross-checked at 25% and 28% against reagent-grade and technical-grade supplier specification sheets — see the validation note above.
Frequently asked questions
A higher percentage is giving me a lower density — did I break the calculator?
No, that's the correct behavior for ammonia. On this site's NaOH and HCl calculators, dissolving more solute makes the solution denser — but aqueous ammonia works the other way: 0% NH3 (plain water) is 0.9982 g/cm³, and by 30% NH3 the density has dropped to about 0.892 g/cm³. If your instinct says "more concentrated should mean heavier," that instinct is right for caustic soda and mineral acids, just not for ammonia — see the section above the calculator for why.
"Ammonia," "ammonium hydroxide," "aqua ammonia" — are these the same thing?
For labeling purposes, yes — all three describe NH3 gas dissolved in water, and this table applies to any of them. "Ammonium hydroxide" (NH4OH) is the traditional formula written on the bottle, but it's a simplification: in solution, only a small fraction of the dissolved NH3 actually reacts with water to form NH4⁺ and OH⁻ ions. Most of it stays as free molecular NH3, which is also why the solution keeps releasing ammonia vapor (that sharp smell) rather than behaving like a fully ionized base.
Is Diesel Exhaust Fluid (DEF) just diluted ammonia?
No, and this is a genuinely common mix-up. DEF is a 32.5% solution of urea in deionized water — it contains no ammonia at all until it hits the hot exhaust stream, where the SCR catalyst thermally breaks the urea down into ammonia on the spot. This calculator's table describes actual aqueous ammonia (the reagent some stationary SCR/SNCR systems at power plants and industrial boilers store and inject directly), not urea solution — DEF has its own, completely different density-vs-concentration curve.
Why does the reference table stop at 30% NH3 instead of going higher?
30% is close to the practical ceiling for aqueous ammonia at room temperature and atmospheric pressure. Push much past it and the solution's vapor pressure climbs sharply — it off-gasses aggressively, fumes visibly when opened, and needs respiratory protection and specialized handling that 25–29% "strong ammonia water" doesn't. Commercially available concentrated ammonium hydroxide tops out in roughly the same 28–30% band for exactly this reason, so there's little practical reference data above it.
Does temperature affect this more than it does for NaOH or HCl?
In one extra way, yes. Like any aqueous solution, ammonia's density shifts a bit with sample temperature, which is why this table (like the others on this site) is fixed to 20°C. But ammonia is also volatile — a warm, opened sample keeps losing dissolved NH3 to the headspace as you measure it, quietly lowering both the true concentration and the reading. NaOH and HCl solutions don't evaporate their solute out from under you like that. Keep the container closed and the sample cool until the moment you measure it.
What is the difference between density and specific gravity?
Density is mass per volume with real units (g/cm³). Specific gravity (SG) is a unitless ratio — the solution's density divided by the density of water under a reference condition, here 20°C water at 0.9982 g/cm³. Because water's density is so close to 1, density in g/cm³ and SG stay numerically close for aqueous ammonia too, but a hydrometer marked "SG" is reading that ratio directly, not grams per milliliter — and remember that for ammonia, a lower SG reading means a stronger solution, not a weaker one.