Once you can count, the next layer of numerical Spanish is the vocabulary for what you do with numbers: arithmetic, percentages, and the units of measurement Spanish speakers actually use. This page covers the four basic operations, percentages (with their characteristic Spanish article el), the metric system as Spain lives it, and the way height, weight, distance, volume and temperature are expressed in normal speech.
The single most important thing to absorb: peninsular Spanish lives entirely in the metric system. Pints, miles, ounces and Fahrenheit are foreign units. Don't translate them — convert them.
The four basic operations
Spanish has clean one-word names for each arithmetic operation, and they parallel the English mathematical vocabulary. The verb after the equation is either es (for one item on the left) or son (for plural).
| Operation | Symbol | Spanish |
|---|---|---|
| addition | + | más |
| subtraction | − | menos |
| multiplication | × | por |
| division | ÷ | entre / dividido por / dividido entre |
| equals | = | es / son / igual a |
Dos más dos son cuatro.
Two plus two is four.
Cinco menos tres son dos.
Five minus three is two.
Seis por siete son cuarenta y dos.
Six times seven is forty-two.
Veinte entre cuatro son cinco.
Twenty divided by four is five.
Diez por diez es igual a cien.
Ten times ten equals one hundred. (formal)
The verb agrees with the result, not the operands. Dos más dos son cuatro (plural result, son); cinco menos cuatro es uno (singular result, es).
Nueve menos ocho es uno.
Nine minus eight is one.
Doce entre dos son seis.
Twelve divided by two is six.
Por: the multiplier word
The word por has many uses in Spanish, and one of them is multiplicative. It glues two numbers together as "times" or "by":
La habitación mide tres por cuatro metros.
The room measures three by four metres.
El folio es de veintiuno por veintinueve coma siete centímetros.
The sheet is 21 by 29.7 centimetres. (A4 paper)
Tres por cuatro son doce.
Three times four is twelve.
This is the same por used in kilómetros por hora ("kilometres per hour") — the distributive sense — so a single tiny preposition does heavy lifting in technical writing.
Percentages: the obligatory article
In Spanish, percentages take a definite article — el 10 por ciento, el 50%, el 100%. English doesn't do this ("10 percent" stands on its own); Spanish does it consistently.
El veinte por ciento de los españoles vive solo.
Twenty per cent of Spaniards live alone.
La tasa de paro juvenil es del veintitrés por ciento, una barbaridad.
The youth unemployment rate is 23%, outrageous.
Te devuelven el 80% si cancelas con antelación.
They refund 80% if you cancel in advance.
The construction with de + percentage uses the merged form del:
Hablamos de un crecimiento del cinco por ciento anual.
We're talking about 5% annual growth.
Una caída del diez por ciento en bolsa.
A 10% drop on the stock market.
The shorthand % can be read aloud as por ciento. Note that por ciento is two separate words (not porciento) in standard spelling, and por cien is incorrect in this fixed expression — even though cien is the form used in counting.
The metric system in everyday speech
Spain uses the Système international (SI) units across the board. The most common ones in daily conversation:
| Quantity | Unit | Abbrev. | Common in speech |
|---|---|---|---|
| length | milímetro | mm | — |
| centímetro | cm | height of people, sizes | |
| metro | m | height, room sizes | |
| kilómetro | km | distances, running | |
| area | metro cuadrado | m² | flats, plots of land |
| volume | centímetro cúbico | cm³ / cc | engines |
| mililitro | ml | medicine, perfumes | |
| litro | l | drinks, fuel | |
| mass | gramo | g | cooking, small items |
| kilogramo (kilo) | kg | weight of people, groceries | |
| tonelada | t | industry, lorries | |
| temperature | grados Celsius | °C | weather, body temperature |
In speech, kilogramo is universally shortened to kilo, and the plural kilos functions as the default word for weight: un kilo de naranjas, peso setenta kilos. The full kilogramo sounds slightly technical.
Compré un kilo de manzanas y medio kilo de queso.
I bought a kilo of apples and half a kilo of cheese.
El piso tiene ochenta y cinco metros cuadrados, con dos balcones.
The flat has 85 square metres, with two balconies.
Bebe al menos dos litros de agua al día.
Drink at least two litres of water a day.
Corre veinte kilómetros antes de desayunar, está loco.
He runs twenty kilometres before breakfast, he's mad.
Heights, weights, and personal measurements
Spanish has a fixed way of expressing how tall someone is and how much they weigh — using the verbs medir (to measure) and pesar (to weigh) without an article.
Mide un metro setenta y cinco.
He's one metre seventy-five tall (1.75 m).
Mi hermana mide uno sesenta y cinco.
My sister is 1.65 m tall.
¿Cuánto mides?
How tall are you?
Pesa unos setenta y dos kilos, más o menos.
He weighs about seventy-two kilos, give or take.
El bebé pesó tres kilos doscientos al nacer.
The baby weighed 3.2 kg at birth.
Note the construction uno sesenta y cinco — in casual speech, the metre is often dropped entirely, so 1.65 m becomes simply uno sesenta y cinco (or un metro sesenta y cinco in full).
Temperatures and the weather
Temperatures use grados with the appropriate number. Below zero, Spanish uses bajo cero ("below zero") or the negative form menos.
Hoy estamos a treinta grados a la sombra.
It's thirty degrees in the shade today.
Ayer hizo menos diez grados en Burgos.
Yesterday it was minus ten degrees in Burgos.
En invierno la temperatura cae por debajo de cero casi todas las noches.
In winter the temperature drops below zero almost every night.
Tiene treinta y nueve y medio de fiebre, hay que llamar al médico.
He's running 39.5° fever — we need to call the doctor.
The preposition is a: estamos a treinta grados, not en treinta grados. The verb estar a is the standard way to give the current temperature.
Distance and speed
Distances are in kilometres. Speed is in kilómetros por hora, abbreviated km/h and read as kilómetros por hora.
Hay unos cuatrocientos kilómetros entre Madrid y Valencia.
It's about 400 km between Madrid and Valencia.
En autovía el límite es de ciento veinte kilómetros por hora.
On a motorway the limit is 120 km/h.
Caminé diez kilómetros y todavía no había llegado.
I walked ten kilometres and still hadn't arrived.
The compound preposition a + speed is used after motion verbs: iba a cien por hora ("he was going a hundred per hour"). In colloquial speech, the km part is often dropped — a cien, a ciento veinte — when the context (driving) is clear.
Cooking, recipes, and small measures
In recipes and shopping, the metric units stay metric but the lexicon is rich and specific.
Añade doscientos gramos de harina y un cuarto de litro de leche.
Add 200 g of flour and a quarter litre of milk.
Necesitas media cucharadita de sal.
You need half a teaspoon of salt.
Compré un cuarto de jamón y doscientos gramos de queso.
I bought a quarter (kilo) of ham and 200 g of cheese.
The fraction un cuarto in the cured-meat counter at a Spanish supermarket means a quarter of a kilo (250 g), not 250 ml or anything else — context fills in the missing unit. Un cuarto y mitad is an idiomatic phrase for 375 g (a quarter of a kilo, plus half of that quarter) — still heard at older delis, though many shoppers today just say trescientos setenta y cinco gramos or simply cuatrocientos gramos.
Currencies and money
The official currency is the euro, abbreviated €, and the unit goes after the number — 5 €, 5 euros — never before, unlike in English.
El menú del día cuesta diez euros con cincuenta.
The lunch menu costs €10.50.
Me han subido el alquiler doscientos euros de golpe.
They've put up my rent two hundred euros at a stroke.
Cuesta tres euros con noventa y cinco.
It costs €3.95.
The construction con + céntimos — diez con cincuenta — is the standard spoken form for prices with cents. You can also say diez euros y cincuenta céntimos, but it sounds slightly more formal.
Common mistakes
❌ Dos más dos es cuatro.
Acceptable but unusual: the verb usually agrees with the plural result (son cuatro).
✅ Dos más dos son cuatro.
Two plus two is four.
❌ Veinte por ciento de los estudiantes aprobó.
Incorrect: percentages take the article el in Spanish.
✅ El veinte por ciento de los estudiantes aprobó.
Twenty percent of the students passed.
❌ Mido cinco pies con ocho pulgadas.
Wrong unit system: Spain uses metric. Convert to metres.
✅ Mido uno setenta y tres.
I'm 1.73 m tall.
❌ Hoy hace ochenta grados Fahrenheit.
Wrong scale for a Spanish context: use Celsius.
✅ Hoy hace veintisiete grados.
It's twenty-seven degrees today.
❌ Compré dos pounds de tomates.
Use kilos or grams, not pounds, in Spain.
✅ Compré un kilo de tomates.
I bought a kilo of tomatoes.
❌ Cuesta dólares diez.
Word order error: the currency goes after the number.
✅ Cuesta diez dólares.
It costs ten dollars.
❌ La tasa es de 5,5 porciento.
Incorrect: por ciento is two separate words in this fixed expression.
✅ La tasa es del 5,5 por ciento.
The rate is 5.5 per cent.
How math and measurement differ from English
The arithmetic vocabulary maps cleanly: más for plus, menos for minus, por for times, entre for divided by. The trap is the verb agreement with the result, which English doesn't have ("two plus two is four" works regardless). The percentages quirk — the obligatory article el before any percentage figure — has no English equivalent at all, and learners drop it constantly because it sounds redundant in their head. The big cultural difference is units. English-speaking learners come from a mixed metric/imperial environment (or a fully imperial one, in the US) and bring habits — pounds, miles, feet, Fahrenheit — that simply don't exist in Spanish supermarkets, weather forecasts, road signs, or doctor's offices. Re-train your reflexes: in a Spanish sentence, always reach for the metric unit. If you find yourself hesitating because you only know your weight in pounds, that hesitation is the work you have to do.
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