Calculator API — 135+ Online Calculators | YEB

135+ online calculators via REST API. Finance, health, math, construction, physics and more. Evaluate formulas, search calculators, get definitions.

API FAQ

Hent API-nøgle Køb kreditter

Try it live

All 135 calculators are available for free on the web app:

Open calculator.yeb.to

✓

135+ calculators
Finance, health, math, construction, physics, chemistry, biology, statistics, and more.

✓

16 categories
Organized by topic for easy discovery and integration.

✓

30 languages
Translated titles, descriptions, and input/output labels.

Endpoint:

99.9 % Oppetid

7ms Svar

20 req/s

0.001 Kreditter / forespørgsel

Calculate


POST https://api.yeb.to/v1/calculator/calculate

Parameter	Type	Påkrævet	Beskrivelse
`api_key`	string	ja	Your API key
`calculator_id`	integer	ja	ID of the calculator to evaluate
`inputs`	object	ja	Input values as key-value pairs (e.g. {"length": 10, "width": 5})
`units`	object	valgfri	Selected units per input/output (e.g. {"length": "m", "area": "m2"})

Eksempel

curl -X POST https://api.yeb.to/v1/calculator/calculate \
  -H "Content-Type: application/json" \
  -d '{
  "api_key": "YOUR_KEY",
  "calculator_id": 1,
  "inputs": {
    "value": 200,
    "percentage": 15
  },
  "units": {}
}'

Svareksempel

{
  "calculator_id": 1,
  "calculator_slug": "percentage",
  "results": {
    "result": {
      "value": 30,
      "unit": null
    },
    "inverse": {
      "value": 7.5,
      "unit": null
    }
  },
  "credits_spent": 0.001,
  "credits_left": 99.99,
  "response_code": 200,
  "response_time_ms": 12
}

{
  "error": "Calculator not found",
  "response_code": 404,
  "response_time_ms": 3
}

Svarkoder

Kode	Beskrivelse
200 Success	Forespørgsel behandlet OK.
400 Bad Request	Inputvalidering mislykkedes.
401 Unauthorized	Manglende / forkert API-nøgle.
403 Forbidden	Nøgle inaktiv eller ikke tilladt.
429 Rate Limit	For mange forespørgsler.
500 Server Error	Uventet fejl.

Calculate

calculator/calculate 0.0010 credits

Method

URL

Authentication

API Key

Parameters

API Key

body · string · required

Calculator ID

body · string · required

Inputs

body · string · required

Units

body · string

Code Samples

Response

Status: —

Headers

Body

List Calculators


POST https://api.yeb.to/v1/calculator/list

Parameter	Type	Påkrævet	Beskrivelse
`api_key`	string	ja	Your API key
`category`	string	valgfri	Filter by category slug (e.g. "finance", "health", "math")
`locale`	string	valgfri	Language code for translated titles (default: en)
`limit`	integer	valgfri	Max results, 1–100 (default: 50)
`offset`	integer	valgfri	Skip N results for pagination (default: 0)

Eksempel

curl -X POST https://api.yeb.to/v1/calculator/list \
  -H "Content-Type: application/json" \
  -d '{
  "api_key": "YOUR_KEY",
  "category": "finance",
  "locale": "en",
  "limit": 5
}'

Svareksempel

{
  "total": 14,
  "offset": 0,
  "limit": 5,
  "calculators": [
    {
      "id": 1,
      "slug": "percentage",
      "title": "Percentage Calculator",
      "short_description": "Calculate what X% of Y is.",
      "category": "finance"
    },
    {
      "id": 2,
      "slug": "percentage-change",
      "title": "Percentage Change Calculator",
      "short_description": "Calculate percentage change between two values.",
      "category": "finance"
    }
  ],
  "credits_spent": 0,
  "credits_left": 100,
  "response_code": 200,
  "response_time_ms": 8
}

{
  "error": "Invalid limit parameter",
  "response_code": 400,
  "response_time_ms": 2
}

Svarkoder

Kode	Beskrivelse
200 Success	Forespørgsel behandlet OK.
400 Bad Request	Inputvalidering mislykkedes.
401 Unauthorized	Manglende / forkert API-nøgle.
403 Forbidden	Nøgle inaktiv eller ikke tilladt.
429 Rate Limit	For mange forespørgsler.
500 Server Error	Uventet fejl.

List Calculators

calculator/list 0.0000 credits

Method

URL

Authentication

API Key

Parameters

API Key

body · string · required

Code Samples

Response

Status: —

Headers

Body

Calculator Info


POST https://api.yeb.to/v1/calculator/info

Parameter	Type	Påkrævet	Beskrivelse
`api_key`	string	ja	Your API key
`slug`	string	valgfri	Calculator slug (e.g. "bmi", "mortgage")
`calculator_id`	integer	valgfri	Calculator ID (alternative to slug)
`locale`	string	valgfri	Language code (default: en)

Eksempel

curl -X POST https://api.yeb.to/v1/calculator/info \
  -H "Content-Type: application/json" \
  -d '{
  "api_key": "YOUR_KEY",
  "slug": "bmi"
}'

Svareksempel

{
  "id": 25,
  "slug": "bmi",
  "title": "BMI Calculator",
  "short_description": "Calculate your Body Mass Index.",
  "formula": {
    "inputs": [
      {"key": "weight", "type": "number", "default": 70, "unit_group": "mass", "default_unit": "kg"},
      {"key": "height", "type": "number", "default": 175, "unit_group": "height", "default_unit": "cm"}
    ],
    "outputs": [
      {"key": "bmi", "expression": "weight / (height * height)", "precision": 1},
      {"key": "category", "expression": "..."}
    ],
    "unit_groups": {
      "mass": {"kg": 1, "lb": 0.453592},
      "height": {"m": 1, "cm": 0.01, "in": 0.0254}
    }
  },
  "input_labels": {"weight": "Weight", "height": "Height"},
  "output_labels": {"bmi": "Your BMI", "category": "Category"},
  "category": {"slug": "health", "name": "Health & Fitness"},
  "credits_spent": 0,
  "response_code": 200
}

{
  "error": "Calculator not found",
  "response_code": 404,
  "response_time_ms": 3
}

Svarkoder

Kode	Beskrivelse
200 Success	Forespørgsel behandlet OK.
400 Bad Request	Inputvalidering mislykkedes.
401 Unauthorized	Manglende / forkert API-nøgle.
403 Forbidden	Nøgle inaktiv eller ikke tilladt.
429 Rate Limit	For mange forespørgsler.
500 Server Error	Uventet fejl.

Calculator Info

calculator/info 0.0000 credits

Method

URL

Authentication

API Key

Parameters

API Key

body · string · required

Slug

body · string

Calculator ID

body · string

Locale

body · string

Code Samples

Response

Status: —

Headers

Body

Search Calculators


POST https://api.yeb.to/v1/calculator/search

Parameter	Type	Påkrævet	Beskrivelse
`api_key`	string	ja	Your API key
`query`	string	ja	Search query (minimum 2 characters)
`locale`	string	valgfri	Language code (default: en)
`limit`	integer	valgfri	Max results, 1–50 (default: 20)

Eksempel

curl -X POST https://api.yeb.to/v1/calculator/search \
  -H "Content-Type: application/json" \
  -d '{
  "api_key": "YOUR_KEY",
  "query": "mortgage",
  "locale": "en",
  "limit": 5
}'

Svareksempel

{
  "query": "mortgage",
  "results": [
    {
      "id": 5,
      "slug": "mortgage",
      "title": "Mortgage Calculator",
      "short_description": "Calculate monthly mortgage payment, total interest, and total amount paid.",
      "category": "finance"
    },
    {
      "id": 9,
      "slug": "amortization",
      "title": "Amortization Calculator",
      "short_description": "See how each payment splits between principal and interest.",
      "category": "finance"
    }
  ],
  "credits_spent": 0,
  "response_code": 200,
  "response_time_ms": 15
}

{
  "error": "Query must be at least 2 characters",
  "response_code": 400,
  "response_time_ms": 2
}

Svarkoder

Kode	Beskrivelse
200 Success	Forespørgsel behandlet OK.
400 Bad Request	Inputvalidering mislykkedes.
401 Unauthorized	Manglende / forkert API-nøgle.
403 Forbidden	Nøgle inaktiv eller ikke tilladt.
429 Rate Limit	For mange forespørgsler.
500 Server Error	Uventet fejl.

Search Calculators

calculator/search 0.0000 credits

Method

URL

Authentication

API Key

Parameters

API Key

body · string · required

Query

body · string · required

Locale

body · string

Limit

body · string

Code Samples

Response

Status: —

Headers

Body

Calculator API — 135+ Online Calculators | YEB — Practical Guide

A hands-on guide to the Calculator API: 135+ online calculators across 16 categories, formula evaluation with unit conversion, multilingual support in 30 languages, and how to integrate it all into your application.

Last updated: 20 mar. 2026, 23:12 API Version: v1 Burst: 20 req/s Latency: 7 ms

#What the Calculator API does

The Calculator API provides 4 endpoints for accessing 135+ online calculators: evaluate formulas with unit conversion, list and search calculators, and get complete formula definitions — all via simple POST requests.

Key advantage: three out of four endpoints are completely free. Only the Calculate endpoint costs credits (0.001 per request). Formula definitions are open, so you can also evaluate client-side if preferred.

#Endpoints at a glance

Endpoint	What it does	Credits
`POST /v1/calculator/calculate`	Evaluate a calculator formula with inputs and unit conversion	0.001
`POST /v1/calculator/list`	List all calculators, optionally filtered by category	FREE
`POST /v1/calculator/info`	Get full formula definition, inputs, outputs, and unit groups	FREE
`POST /v1/calculator/search`	Search calculators by keyword across all categories	FREE

#Available categories

135 calculators are organized into 16 categories:

Category	Slug	Count	Examples
Finance	`finance`	14	Percentage, Mortgage, Compound Interest, ROI, CAGR
Salary & Tax	`salary-tax`	10	Gross/Net, VAT, Tip, Discount, Margin, Retirement
Health & Fitness	`health`	12	BMI, Calories (TDEE), BMR, Body Fat, Protein
Pregnancy	`pregnancy`	5	Due Date, Ovulation, Period, Fertility Window
Math	`math`	10	Fraction, Quadratic Formula, GPA, Logarithm
Conversion	`conversion`	10	Weight, Length, Temperature, Speed, Pressure
Time & Date	`time-date`	7	Age, Days Between Dates, Countdown, Time Zone
Construction	`construction`	9	Concrete, Brick, Tile, Paint, Roofing
Automotive	`automotive`	8	Fuel Cost, Tire Size, Horsepower, 0-100 km/h
Physics	`physics`	8	Free Fall, Force, Kinetic Energy, Projectile Motion
Chemistry	`chemistry`	7	Molar Mass, pH, Dilution, Percent Yield
Biology	`biology`	6	Punnett Square, DNA, Bacteria Growth
Statistics	`statistics`	8	Std Deviation, Confidence Interval, Z-Score
Food & Cooking	`food`	8	Pizza, Coffee, Grams to Cups, Recipe Scaler
Sports	`sports`	7	Calories Burned, Pace, Marathon, VO2 Max
Fun & Viral	`fun`	6	Love Compatibility, Lucky Number, Zodiac

#How the formula system works

Each calculator stores its formula as a JSON definition with inputs, outputs, unit groups, and constants. The formula engine supports arithmetic, ternary expressions, and built-in math functions (sqrt, sin, cos, log, pow, min, max, etc.).

Use the info endpoint to retrieve the complete formula definition for any calculator. You can then evaluate it server-side via the calculate endpoint, or implement client-side evaluation using the same expression language.

Unit conversion is automatic. Define unit groups (e.g. length: m, cm, ft, in) with conversion factors. Inputs are normalized to base units before evaluation, and outputs are converted to the user's selected display unit.

#Multilingual support

All 135 calculators are translated into 30 languages: English, Bulgarian, Spanish, German, French, Italian, Portuguese, Russian, Polish, Dutch, Turkish, Czech, Romanian, Hungarian, Ukrainian, Swedish, Danish, Finnish, Norwegian, Greek, Arabic, Hebrew, Japanese, Korean, Chinese (Simplified & Traditional), Thai, Vietnamese, Indonesian, and Malay.

Use the locale parameter on the list, info, and search endpoints to get translated titles, descriptions, input/output labels, and educational content.

#Common use cases

Embedded calculators — add interactive calculators to your website or app
Education platforms — provide step-by-step calculations for students
Health & fitness apps — BMI, calorie, and body composition calculations
Real estate tools — mortgage, loan, and amortization calculations
Construction estimators — material quantity and cost calculators
Chatbots & AI assistants — answer calculation questions programmatically
Comparison tools — evaluate multiple scenarios with different inputs

#Try it live

All 135 calculators are available for free on calculator.yeb.to. Each calculator has an interactive widget, educational article, FAQ section, and SEO-optimized pages in 30 languages. The web app uses the same formula engine as the API.

Ofte stillede spørgsmål

135+ calculators across 16 categories: finance (percentage, mortgage, compound interest, ROI), health (BMI, calories, body fat), math (quadratic formula, logarithm), construction (concrete, brick, tile), physics (free fall, kinetic energy), chemistry (molar mass, pH), and more.

The Calculate endpoint costs 0.001 credits per request. List, Info, and Search endpoints are completely free. Sign up to get free credits.

All 135 calculators are translated into 30 languages including English, Spanish, German, French, Bulgarian, Russian, Japanese, Chinese, Arabic, and more. Use the locale parameter to get translated content.

Yes! Use the Info endpoint with a calculator slug to get the complete formula definition including inputs, outputs, expressions, unit groups, and constants. You can evaluate formulas client-side or via the Calculate endpoint.

Each calculator defines unit groups with conversion factors. When you send a units parameter with your Calculate request, inputs are automatically converted to base units before evaluation, and outputs are converted to your selected display units.

Ja. Hver forespørgsel, selv dem der resulterer i fejl, forbruger kreditter. Dine kreditter er bundet til antallet af forespørgsler, uanset succes eller fejl. Hvis fejlen tydeligt skyldes et platformproblem på vores side, gendanner vi de berørte kreditter (ingen kontant refusion).

Kontakt os på [email protected]. Vi tager feedback alvorligt—hvis din fejlrapport eller funktionsanmodning er meningsfuld, kan vi rette eller forbedre API'et hurtigt og give dig 50 gratis kreditter som tak.

Det afhænger af API'et og nogle gange endda af endpointet. Nogle endpoints bruger data fra eksterne kilder, som kan have strengere grænser. Vi håndhæver også grænser for at forhindre misbrug og holde vores platform stabil. Se dokumentationen for den specifikke hastighedsgrænse for hvert endpoint.

Vi opererer med et kreditsystem. Kreditter er forudbetalte, ikke-refunderbare enheder, du bruger på API-kald og værktøjer. Kreditter forbruges FIFO (ældste først) og er gyldige i 12 måneder fra købsdatoen. Dashboardet viser hver købsdato og dens udløb.

Ja. Alle købte kreditter (inklusive brøkdele) er gyldige i 12 måneder fra købet. Ubrugte kreditter udløber automatisk og slettes permanent ved udgangen af gyldighedsperioden. Udløbne kreditter kan ikke gendannes eller konverteres til kontanter eller anden værdi. Overgangsregel: kreditter købt før 22. sep. 2025 behandles som købt den 22. sep. 2025 og udløber den 22. sep. 2026 (medmindre en tidligere udløbsdato var angivet ved købet).

Ja—inden for deres gyldighedsperiode. Ubrugte kreditter forbliver tilgængelige og overføres fra måned til måned, indtil de udløber 12 måneder efter købet.

Kreditter er ikke-refunderbare. Køb kun det, du har brug for—du kan altid fylde op senere. Hvis en platformfejl forårsager en mislykket opkrævning, kan vi gendanne de berørte kreditter efter undersøgelse. Ingen kontant refusion.

Priser er angivet i kreditter, ikke dollars. Hvert endpoint har sin egen pris—se mærket "Kreditter / forespørgsel" ovenfor. Du ved altid præcis, hvad du bruger.

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Få kreditter for at låse op for premium indhold og funktioner

Kundetype

Faktureringsland

API / Endpoint

Valuta

# af forespørgsler

Calculator API — 135+ Online Calculators | YEB

Try it live

Calculate

Eksempel

Svareksempel

Svarkoder

Calculate

Parameters

Code Samples

Response

List Calculators

Eksempel

Svareksempel

Svarkoder

List Calculators

Parameters

Code Samples

Response

Calculator Info

Eksempel

Svareksempel

Svarkoder

Calculator Info

Parameters

Code Samples

Response

Search Calculators

Eksempel

Svareksempel

Svarkoder

Search Calculators

Parameters

Code Samples

Response

Calculator API — 135+ Online Calculators | YEB — Practical Guide

#What the Calculator API does

#Endpoints at a glance

#Available categories

#How the formula system works

#Multilingual support

#Common use cases

#Try it live

Ofte stillede spørgsmål

What calculators are available?

How much does it cost?

What languages are supported?

Can I get the formula definition?

How does unit conversion work?

Tæller fejlbehæftede forespørgsler og koster de kreditter?

Jeg fandt en fejl eller ønsker tilpasninger i API'erne. Hvad gør jeg?

Hvad er hastighedsgrænsen?

Hvordan fungerer betaling og brug?

Udløber kreditter?

Overføres ubrugte kreditter?

Tilbyder I refusioner?

Hvad koster hvert API-kald?