Conversion
Conversion Calculators
Convert a quantity from one unit into another, and see the factor or the standard that did it. This category is deliberately the specialist half of unit conversion: if you want centimetres in inches, a search box answers instantly and these pages are not trying to beat it. What sits here is the set of conversions a one-line widget cannot do honestly — an NPK fertilizer grade that means a different thing as oxide or as element, a thread pitch quoted as teeth per inch, a wire gauge that runs backwards, a viscosity that needs a density before it means anything, a tyre code that is part ratio and part millimetre, and two number systems that use the same word for different quantities, as a German Billion is a US trillion. Where a conversion is exact by definition the page shows the defining constant rather than a rounded decimal; where it is derived from a density, a temperature or a named industry standard, it says so instead of assuming one. What lives here is the conversion itself; a tool whose real subject is a body, a house, a kitchen or a race sits in that category instead — blood-test and supplement units under Health, a gas meter or a solar rating under Home & Energy, clothing and shoe sizes under Everyday, running pace under Sports.
Number Systems
Agriculture
Fuel
Area
Speed
Pressure
Kitchen
Data
Energy
Angle
Power
Density
Torque
Digital
Geographic
Mapping
Fasteners
Aviation
Signal
Automotive
Magnetism
Particle
Screen
Concentration
Chemistry
Precious Metals
Building
Fluids
Electrical
Mechanics
Light
Photography
Materials
Length
Sound
Weather
Land
Geometry
Acoustics
Engineering
Physics
Text
Who this is for
Built for anyone who has to restate a quantity in someone else’s units and needs to see the factor rather than trust it: a grower reading a fertiliser bag or a grain contract, a machinist matching a thread, an electrician sizing a conductor, a jeweller checking a hallmark, an engineer moving between magnetic or viscosity units on a spec sheet, and a reader working out whether a European “billion” means the same thing their own does.
How to choose a calculator
58 tools here so far, and they are deliberately the conversions a search box gets wrong rather than the ones it already answers. If you want centimetres in inches, use the search box. What is here is the set where the answer depends on a convention, a standard or a second measurement that a one-line widget does not ask for.
Start with the ones that hide a definition. The NPK Fertilizer Converter turns a grade into the nutrient actually in the bag, because the second and third numbers are oxides rather than elements — 10-10-10 is really 10-4.4-8.3. The Gold Purity Converter moves between karat, fineness, tola and troy ounce and says what a 916 stamp means. The Bushel to kg Converter covers eleven crops separately, because a bushel is a volume sold at a different weight for each one.
Three answer a question about a machine part rather than a quantity. The TPI to mm Pitch Converter carries the flank angle and taper that decide whether two threads actually mate, which the pitch alone does not. The Wire Gauge Converter puts AWG and SWG into mm, mm² and circular mils with resistance and voltage drop, and names the 14–21% gap the equivalence charts paper over. The Tyre Size Calculator reads a sidewall code into diameter and rolling circumference, and says how far a size change throws the speedometer out.
Three need a second measurement before they mean anything, and each one asks for it rather than assuming a default. The Viscosity Converter needs the density to cross between dynamic and kinematic units, and shows that the Saybolt 4.63 figure is a curve rather than a constant. The EC to TDS Converter prints all three ppm scales at once, because the factor is a meter’s convention and not a property of the water. The Octane Rating Converter gives RON, MON and AKI with a real uncertainty band, since no pump prints the sensitivity the conversion needs.
Three keep apart quantities that share a vocabulary. The Gauss to Tesla Converter groups tesla, gauss, oersted and weber by the quantity each measures, because gauss and oersted are not the same thing and only coincide in free space. The Force Converter keeps mass in its own panel and the three tons-force apart. The Textile Weight Converter holds yarn count and fabric weight apart, because no factor connects tex to GSM.
Two are screen geometry. The Pixel Density Calculator gives PPI, dot pitch and physical size from a resolution, and pixels per degree, which is what actually decides whether a pixel is visible from where you sit. The Aspect Ratio Calculator gives the exact ratio, the missing dimension, and what letterboxing costs — and flags the resolutions that are not the ratio they are sold as.
The Area Converter squares the factors for you, because a metre is 3.28 feet while a square metre is 10.76 square feet, and the mistake of using the length factor twice over is the commonest one in the dimension. The Energy Converter covers food, electrical and heating energy together and carries the two calories apart: a small calorie is 4.184 J, while the Calorie on a nutrition label is a kilocalorie, a thousand times larger and distinguished only by a capital letter.
Two are about how a number is written rather than what it measures. The Million, Billion and Trillion Converter handles the case where two conventions use the same word for different quantities — a German or French “Billion” is a US trillion — which is more dangerous than two conventions using different words, because nothing signals that a translation is needed. The Roman Numerals Converter transcribes between two ways of writing the same whole number, reads the older spellings you actually meet such as the clock-face IIII, and writes the standard modern form back.
Not all of these are exact. Where a conversion is fixed by definition the page shows the defining constant rather than a rounded decimal, so the result can be checked by hand. Where it depends on a density, a temperature, a meter convention or a named industry standard — viscosity, EC to TDS, octane, flight level — the page says so and asks for the missing input, instead of picking a default and returning a number it cannot justify.
Compare conversion calculators
What each calculator is best for, the main inputs it needs, what it shows, and what to keep in mind.
| Calculator | Best for | Key inputs | Shows | Keep in mind |
|---|---|---|---|---|
| Text Case Converter | Headlines and identifiers, where the styles genuinely differ | Any text — a headline, a variable name, a paragraph | Every case style at once, including three separate title-case styles, with word and character counts | No automatic case can know your proper nouns, and case conversion is locale-dependent — the tool flags text that lower-cases differently in Turkish |
| Coordinates Converter | Coordinates copied from a document, where the digits look like a decimal | Degrees, minutes, seconds and a hemisphere — or a decimal figure, for latitude or longitude | Both notations, plus a live figure for how far the digits-run-together misreading would land you from the real point | A coordinate needs a datum as well as numbers, and this page assumes none — the same point differs by about 100 m between OSGB36 and WGS 84 in Britain |
| Colour Converter | Picking a colour that text will actually be readable on | A hex code in three or six digits, with or without the hash, or an rgb() value | Hex, RGB and HSL together, plus the WCAG contrast ratio against white and black with a plain pass-or-fail verdict | A contrast ratio is a floor rather than a target — it does not model font weight, and it does not flag pairs that are specifically hard for colour-blind readers |
| Torque Converter | Fastener specs, where in·lb and ft·lb sit on the same sheet | A torque figure and the unit it is in — N·m, pound-feet, pound-inches, ounce-inches or kgf·m | Every torque unit at once, with the twelve-fold pair named apart rather than left to be read carefully | Refuses to convert torque into energy despite identical dimensions. And a converted figure cannot carry the spec’s conditions — a thread lubricated where the spec said dry gains 20–30% clamping force at the same reading |
| Numeral Base Converter | Byte dumps, permissions and colour codes, where hex and binary are the same bits | A value and the base it is written in — binary, octal, decimal, hex, base 32 or base 36; plus a width when the value is negative | Every base at once, with the 4-bit grouping that maps binary onto hex shown rather than asserted | A negative has no binary form without a width, and a value outside that width’s signed range is refused rather than wrapped into a valid encoding of a different number |
| Fuel Economy Converter | Comparing a car quoted in one market against one quoted in another | An economy figure and the unit it was quoted in — US mpg, imperial mpg, km/L or L/100 km | Every unit at once with the better direction labelled, the fuel used over 15,000 miles, and a table showing why small mpg gains beat large ones | The conversion is exact but the label figure is a test-cycle result — European figures moved from NEDC to WLTP and read 10–20% worse for the same car |
| Roman Numerals Converter | Years on cornerstones and credits, regnal numbers, and clock faces | A whole number from 1 to 3,999, or a numeral — including older spellings such as IIII | The number and its standard modern numeral side by side, with a reference table generated by the same engine | Refuses zero, negatives, fractions and anything above 3,999 rather than inventing notation — the system genuinely has no symbols for them |
| Volume to Weight Converter | Fuel, aggregates and ingredients, where the substance decides the answer | An amount, the volume and weight units, and — the part that makes it answerable — which substance it is | A typical figure alongside the realistic low-to-high range, with the reason for that range stated on the result | The only tool here whose answer is not exact. Densities move with moisture, compaction and grade, so this is for planning — a load that will be paid for should be weighed |
| Power Converter | Comparing an engine or appliance rating quoted in another market’s units | An amount and the unit it is in — watts, kilowatts, mechanical horsepower, metric horsepower or BTU per hour | Both horsepower listed apart, alongside the metric scale and the BTU/h used for heating and cooling capacity | The factors are exact but a RATING is not — pre-1972 SAE gross figures read about 20% high, and volt-amperes are not watts unless the power factor is 1 |
| Angle Converter | Trigonometry and coordinates, where degrees and radians get mixed up | An amount and the unit it is in — degrees, radians, gradians, turns, arcminutes or arcseconds | Every angle unit at once, with the π-based factors flagged as approximate rather than defined | These are the only inexact factors on the site, because π is irrational — and a spreadsheet’s SIN() takes radians, so SIN(90) returns 0.894 rather than 1 |
| Energy Converter | Nutrition labels and utility bills, where “calorie” means two different things | An amount and the unit it is in — joules, small calories, food Calories, watt-hours, BTU or therms | Food, electrical and heating energy in one list, with the small calorie and the food Calorie carried apart rather than merged | Energy is not power — converting one into the other throws rather than guessing. And a label Calorie is a measurement of the food, not of how much of it you absorb |
| Data Storage Converter | Capacity figures, where a “GB” may mean 10⁹ bytes or 2³⁰ and the label does not say | An amount and the unit it is in — bits and bytes, decimal kB to PB, and binary KiB to PiB | Both prefix systems at once under their real names, so the gap between them is visible rather than assumed | Both systems are exact — the difference is a definition, not a discrepancy. Formatted capacity is a separate reduction again, and RAM is genuinely binary |
| Area Converter | Floor and land area, where reaching for the length factor is a threefold error | An amount and the unit it is in — square units, acres, hectares, ares and the cent | Every area unit at once, with factors derived by squaring the exact length factors rather than stored separately | Carries only land units with one settled definition — the bigha, katha and gunta genuinely differ by Indian state, so no national figure is offered for them |
| Speed Converter | Speed limits abroad, and any figure quoted in knots | An amount and the unit it is in — mph, km/h, m/s, ft/s or knots | Every speed unit at once, with the nautical mile behind the knot explained rather than assumed | Pace in minutes per kilometre is a reciprocal rather than a speed unit and is deliberately not offered here; average speed is also not the mean of the speeds along the way |
| Pressure Converter | Tyre, hydraulic and process pressures, where psig and psia are 14.7 psi apart | An amount and the unit it is in — psi, ksi, bar, kPa, MPa, atm, torr, mmHg or kgf/cm² | Every pressure unit at once, with the torr and the millimetre of mercury carried separately rather than merged | Gauge and absolute pressure differ by an offset, not a factor, so no conversion bridges them — the tool says which question is which rather than inventing a local atmospheric pressure |
| Million, Billion and Trillion Converter | Reading a large figure when the source did not say which convention its “billion” follows | An amount and the scale name it was written as, chosen from the short-scale or long-scale list | Both naming conventions side by side, the full figure in grouped digits and in words, and a warning when the name you picked means a different number elsewhere | Exact arithmetic, but no tool can resolve an ambiguous source — if a document says “billion” without stating its convention, the date, language and publisher are the evidence, not the number |
| Lakh and Crore Converter | Reading a figure quoted in lakh or crore when you think in millions, or the reverse | A number, and which system it is written in — Indian (thousand, lakh, crore, arab) or international (thousand, million, billion, trillion) | The same quantity in both systems at once, the Indian 2,2,3 comma grouping alongside the international 3,3,3 one, the amount written out in words, and a reference table from one lakh to one lakh crore | Exact by definition, so the arithmetic cannot drift — but it converts scale only, never currency; a rupee figure still needs a dated exchange rate applied separately |
Best calculator path
- Pick the converter whose subject matches yours — a fertiliser grade, a thread, a conductor, a hallmark, a screen — rather than the dimension it happens to use.
- Read what the page says it needs. Several of these cannot answer from one number alone: viscosity needs a density, EC to TDS needs a scale, octane needs a sensitivity.
- Check the factor or standard the page prints beside the result, so the arithmetic can be repeated by hand rather than trusted.
- Where two conventions share a word — a billion, a ton-force, a gauss against an oersted — confirm which one your source meant before you carry the figure anywhere.
Common mistakes and limits
- Using a length factor on an area or a volume. A metre is 3.28 feet, so a square metre is 10.76 square feet and a cubic metre 35.3 cubic feet — applying 3.28 once is out by a factor of three, and the answer still looks plausible.
- Reading a fertiliser grade as elemental. The P and K figures on a bag are P2O5 and K2O, so a 10-10-10 carries about 4.4% phosphorus and 8.3% potassium — a soil test written in elements and a bag written in oxides are not directly comparable.
- Converting a viscosity, an EC reading or an octane number without the second input the conversion depends on. A default density or a default ppm scale turns a conversion into an assumption, and the error travels silently into whatever you do next.
- Trusting a wire or thread equivalence chart. AWG and SWG differ by 14–21% depending on the size, and a thread that shares a pitch can still refuse to mate if the flank angle or taper differs.
- Assuming “billion” is stable. The short-scale billion (109) is standard in English-language finance, but older British and several continental European usages put it at 1012. When a source is old or translated, check which one it means before converting anything.
When not to rely on calculators alone
A conversion is only as good as the unit it started in. The arithmetic on these pages is exact where the factor is exact, but it cannot tell you whether a quoted ton was metric, long or short, whether a soil report was written in elements or oxides, or whether a spec sheet meant gauge pressure or absolute. For anything that has to hold up — a purchase order, a drawing, an agronomic recommendation, an electrical install — confirm the unit against the document that defined it, and against the standard or code your work is held to.
Source and calculation basis
These are definition- and standard-based tools with no external data feed: every figure is computed from what you type. Where a factor is fixed by definition the page names the defining value it used; where the conversion rests on a published standard — a wire gauge table, a thread series, a Saybolt correlation, a ppm scale convention, the oxide-to-element factors for phosphorus and potassium — the page names that standard instead of presenting the result as if it were exact. Conversions that need a density, a temperature or an instrument convention ask for it rather than assuming one.
See the Methodology for how calculators are built and reviewed, who runs the site, the Disclaimer for the full terms, and the Contact page to report an issue.
Built and maintained by Jay Sudha · Last reviewed 15 September 2026. See a formula issue, unclear assumption, or broken result? Report it through the contact page.
Frequently asked questions
Common questions about conversion calculators and how to use them.
What calculators are in the Conversion section?
58 so far, and they are the specialist half of unit conversion rather than the everyday half. Several hide a definition inside the number: the NPK Fertilizer Converter turns a bag grade into the nutrient actually in it, because the second and third figures are oxides rather than elements; the Gold Purity Converter moves between karat, fineness, tola and troy ounce; the Bushel to kg Converter treats eleven crops separately, because a bushel is a volume sold at a different weight for each. Three are about a machine part rather than a quantity — the TPI to mm Pitch Converter, which carries the flank angle and taper that decide whether two threads mate; the Wire Gauge Converter, which puts AWG and SWG into mm, mm² and circular mils with resistance and voltage drop; and the Tyre Size Calculator, which reads a sidewall code into diameter, rolling circumference and speedometer error. Three need a second measurement before they mean anything and ask for it rather than assuming one: the Viscosity Converter, the EC to TDS Converter and the Octane Rating Converter. Three keep apart quantities that share a vocabulary: the Gauss to Tesla Converter, the Force Converter and the Textile Weight Converter. Two are screen geometry, the Pixel Density Calculator and the Aspect Ratio Calculator; the Flight Level to Feet Converter turns a flight level into a real height using the day’s altimeter setting; the Area Converter squares the factors for you and the Energy Converter carries the small calorie and the food Calorie apart; and two are about how a number is written rather than what it measures, the Million, Billion and Trillion Converter and the Roman Numerals Converter.
Why does a converter need a whole category when phones and search boxes already convert units?
For the simple cases it does not, and that is said plainly: if you want centimetres in inches, your search box answers instantly and these pages are not trying to beat it. The tools here exist for the conversions a one-line widget cannot do honestly. Turning a kinematic viscosity into a dynamic one needs the density of the specific fluid. Turning an EC reading into ppm needs to know which of three meter conventions your meter uses. Reading a fertiliser grade needs to know that the P and K figures are oxides. Those are the cases where showing the assumption matters more than showing the answer, and where a converter that hides the input is returning a number it cannot justify.
Are the conversion factors exact or rounded?
Both, and each page says which it is using. Where a factor is fixed by definition the page names the defining value rather than a rounded decimal — a tesla is exactly 10,000 gauss, a troy ounce is exactly 31.1034768 grams, a newton is exactly one kilogram-metre per second squared — so the arithmetic carries no uncertainty and a result can be checked by hand. Where the conversion rests on a published standard or a measured property it is derived rather than defined, and the page says so instead of implying otherwise: the Saybolt viscosity correlation is a curve, the EC-to-ppm factor is a meter convention, an octane conversion needs a fuel’s sensitivity that no pump prints, and a wire gauge equivalence is a table rather than a ratio. Where a result differs from another tool on an exact factor, it is a rounding or display decision rather than a disagreement about the factor.
Why is a lakh and crore converter here rather than in the Math section?
Because the intent is transcription, not calculation. Someone converting 250 crore to billions is reading a figure written in one convention and needs it in another; no mathematics is in question and the underlying quantity never changes. The Math category owns operations performed on numbers — percentages, algebra, statistics. Conversion owns restating the same quantity in a different unit or notation, which is a different question even when both are arithmetic underneath.
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