Mixtures & Solutions
Water and lab chemistry calculators built around one recurring question: how concentrated is a solution, and how does that concentration actually behave under real conditions. The Alkalinity and Ammonia PPM Calculators handle water-testing math, the Activity Coefficient Calculator corrects concentration for ionic strength, and the Alligation and Bleach Dilution Calculators work out mixing ratios for everything from pharmacy compounding to household sanitizing.
Calculators & Tools
Concentration Calculator
The Concentration Calculator is a unit converter hub: enter a value in molarity, molality, mass percent, ppm, ppb, or mg/L, and it works out every other unit at once using the solute's molar mass and the solution's density. Replaces the need for separate percent-to-molarity and percent-to-ppm converters with one bidirectional tool.
Bleach Dilution Calculator
The Bleach Dilution Calculator works out exact bleach and water quantities for a target chlorine concentration, with presets for food-contact sanitizing, general surface disinfecting, and bloodborne pathogen cleanup, accounting for whether the bleach is 5.25%, 6%, or 8.25% strength. A separate Emergency Drinking Water mode runs the CDC's drops-per-gallon method for disinfecting water in an emergency.
Dilution Calculator
The Dilution Calculator solves the C1V1 = C2V2 dilution equation for any of the four variables, stock concentration, stock volume, final concentration, or final volume, then shows the exact diluent volume to add plus both the dilution factor and dilution ratio side by side. General-purpose and unit-agnostic, not tied to a specific chemical like bleach.
Percent Solution Calculator
The Percent Solution Calculator computes % w/v (grams of solute per 100 mL of solution, standard for solids dissolved in liquids) and % v/v (mL of solute per 100 mL of solution, standard for liquids dissolved in liquids). Covers the volume-referenced percent formats specifically; distinct from the mass-referenced % w/w handled by the General PPM Calculator's Mass/Mass mode.
Alkalinity Calculator
The Alkalinity Calculator computes total alkalinity in mg/L as CaCO3 either from titration data (titrant volume, acid normality, sample volume) or from known carbonate, bicarbonate, and hydroxide concentrations. Its Convert & Compare mode converts between mg/L, meq/L, and dKH and checks the result against drinking water, pool, freshwater aquarium, and reef aquarium target ranges side by side.
Alligation Calculator
The Alligation Calculator works out the mixing ratio of two ingredients at different strengths needed to hit a target strength, using the classic alligation alternate grid, then converts that ratio directly into actual quantities for a specified batch size. A built-in Diluting With Water toggle handles the common special case of diluting one active solution down to a target strength.
Activity Coefficient Calculator
The Activity Coefficient Calculator computes ionic strength directly from a list of ions and their concentrations, then estimates the activity coefficient (gamma) for a target ion using three standard models side by side: Debye-Hückel limiting law, Extended Debye-Hückel (with a built-in ion-size parameter lookup), and the Davies equation. Each result is flagged if it falls outside that model's valid ionic strength range.
EC to PPM Converter
The EC to PPM Converter takes an electrical conductivity reading and converts it to PPM across all three scales in active use, 500, 640, and 700, at the same time, since the same EC reading produces meaningfully different PPM numbers depending on which scale a meter or nutrient chart assumes. Also shows conductivity factor (CF) for Bluelab/Truncheon-style meters and compares the reading against typical target EC ranges for common hydroponic crops.
Chlorine PPM Calculator
The Chlorine PPM Calculator works out how much chlorine product, liquid, cal-hypo, dichlor, trichlor, or gas, is needed to raise a known water volume from a current to target ppm. Its Breakpoint Chlorination mode calculates the larger dose needed to overcome chloramine buildup specifically, using the standard 10x combined-chlorine rule, a calculation most bleach-focused dilution tools skip entirely.
Water Hardness Calculator
The Water Hardness Calculator computes total hardness (mg/L as CaCO3 = 2.497 x Calcium + 4.118 x Magnesium) with automatic conversion to grains per gallon and degrees dH plus a soft-to-very-hard classification, and separately estimates water softener regeneration frequency from daily water use, hardness in gpg, and softener grain capacity. Distinct from the TDS Calculator (all dissolved solids, not just Ca/Mg) and Alkalinity Calculator (acid-buffering capacity from carbonate/bicarbonate, unrelated to calcium or magnesium).
Mixing Ratio Calculator
The Mixing Ratio Calculator computes two-part mixing ratios (Part A : Part B), such as 2-stroke fuel-oil ratios and epoxy resin-hardener ratios, either from a known amount of one part or from a target total mixed amount. Distinct from the meteorological mixing ratio (already covered by the site's Humidity Calculator) and from concentration-based tools like PPM or percent solution calculators, since a ratio describes parts relative to each other, not a component relative to a whole.
Neutralization Calculator
The Neutralization Calculator computes the volume of base needed to fully neutralize a given acid using the equivalents-based formula MaVana=MbVbnb, accounting for polyprotic acids and bases. Also includes a practical baking soda (NaHCO3) spill neutralization estimator for common household and lab acids. Distinct from the Buffer pH Calculator, which covers buffer equilibrium rather than complete neutralization.
Ammonia PPM Calculator
The Ammonia PPM Calculator works out how much of a total ammonia reading is actually toxic to fish, using the standard pH- and temperature-dependent Emerson equation, and flags the result as safe, caution, or dangerous based on species sensitivity. Its Unit Convert mode also handles straightforward mg/L, ppm, and mmol/L conversion for lab or reporting use.
Fertilizer PPM Calculator
The Fertilizer PPM Calculator converts a fertilizer's guaranteed analysis percentage, mixing rate, and optional injector dilution ratio into the actual delivered PPM of nitrogen, phosphorus, or potassium, converting oxide label forms (P2O5, K2O) to elemental nutrient automatically. Distinct from EC-based PPM estimation, this works directly from label and mixing data rather than a conductivity meter reading.
Fluoride PPM Calculator
The Fluoride PPM Calculator checks a known fluoride concentration against official reference levels, the CDC's 0.7 ppm optimal target, the EPA's 2.0 ppm secondary standard, and the EPA's 4.0 ppm maximum contaminant level, side by side. Its Municipal Dosing mode calculates the pounds per day of sodium fluoride, sodium fluorosilicate, or fluorosilicic acid needed to reach a target level above natural background.
Buffer pH Calculator
The Buffer pH Calculator uses the Henderson-Hasselbalch equation to find a buffer's pH from pKa and concentrations, solve backward for the conjugate base to acid ratio needed to hit a target pH, or work out the actual grams and moles needed to prepare a buffer at a target volume and concentration. Preset common buffer systems, acetate, phosphate, Tris, and more, load pKa and typical molar masses automatically.
TDS Calculator
The TDS Calculator computes Total Dissolved Solids by the gravimetric method (TDS = (Final Weight - Initial Weight) x 1,000 / Sample Volume) or by summing major dissolved ion concentrations, and rates any TDS value against the WHO palatability scale (excellent under 300, good 300-600, fair 600-900, poor 900-1200, unacceptable over 1200 mg/L). Distinct from the EC to PPM Converter, which estimates TDS from a conductivity meter reading rather than from direct gravimetric or ion data.
Saponification Value Calculator
The Saponification Value Calculator computes lye (NaOH or KOH) needed for a multi-oil soap recipe using each oil's published SAP value with a configurable superfat/lye discount, and separately computes measured saponification value from titration data using SV = (Blank - Sample) x Molarity x 56.1 / Sample Weight, the standard mg KOH per gram analytical formula. Covers both the practical soap-making use case and the analytical chemistry/QC lab use case in one tool.
Iron PPM in Water Calculator
The Iron PPM in Water Calculator compares an iron reading against the EPA Secondary Maximum Contaminant Level (0.3 ppm) and the lower staining/taste threshold, and converts PPM (mg/L) to grains per gallon for water treatment equipment sizing. Content covers the ferrous versus ferric iron distinction and why a water softener alone often can't fix high iron.
Raoult's Law Calculator
The Raoult's Law Calculator computes partial and total vapor pressure for a binary solution using P_i = X_i x P°_i (ideal), or P_i = X_i x gamma_i x P°_i (non-ideal, with activity coefficient correction), flagging positive or negative deviation from ideal behavior. Includes real preset pairs (benzene/toluene near-ideal, ethanol/hexane positive deviation, acetone/chloroform negative deviation). Distinct from the Activity Coefficient Calculator, which covers ionic strength for electrolyte solutions rather than vapor-liquid equilibrium.