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[Open the Density Calculator on miniwebtool.com →](https://miniwebtool.com/density-calculator/) [Start free — get a key →](/billing/checkout/?plan=free) 1,000 credits · no card · 30 seconds ### Endpoint POST · 1cr ```text POST https://api.miniwebtool.com/v1/tools/density-calculator/run ``` ### Request body Field Type Req. `solve_for` density | mass | volume `str` — `mass` `float | None` — `volume` `float | None` — `density` `float | None` — `mass_unit` mg | g | kg | tonne | oz | lb `str` — `volume_unit` mm3 | cm3 | dm3 | m3 | mL | L | in3 | ft3 | gal_us | gal_uk `str` — `density_unit` g/cm3 | kg/m3 | kg/L | lb/ft3 | lb/in3 | lb/gal `str` — ### Cost & access - 1 credit per successful call — failed calls refund. - Starts on: Free. - Max payload:`65536`bytes. - Privacy mode:`hash_only` - Available on: free, starter, pro, business, scale ### Response envelope ```text { "request_id": "01K...", "tool": "density-calculator", "tool_version": "2026-04-22", "credits_used": 1, "result": {... } } ``` ### Try it API key * Stored only in this browser tab. Playground test key is prefilled and only works on this page. [Get a live key →](/billing/checkout/?plan=free) solve_for (str) density mass volume density | mass | volume mass (float | None) volume (float | None) density (float | None) mass_unit (str) mg g kg tonne oz lb mg | g | kg | tonne | oz | lb volume_unit (str) mm3 cm3 dm3 m3 mL L in3 ft3 gal_us gal_uk mm3 | cm3 | dm3 | m3 | mL | L | in3 | ft3 | gal_us | gal_uk density_unit (str) g/cm3 kg/m3 kg/L lb/ft3 lb/in3 lb/gal g/cm3 | kg/m3 | kg/L | lb/ft3 | lb/in3 | lb/gal Send request → Response copy body This endpoint starts on Free Your key is valid, but its current plan cannot call`density-calculator`. Upgrade to Free or higher to run this tool. [Start Free →](/billing/checkout/?plan=free) [Compare plans](/#pricing) ```text ``` Response headers ```text ``` ### Code examples cURL Python JavaScript PHP Ruby Go Java copy ```text curl -X POST https://api.miniwebtool.com/v1/tools/density-calculator/run \ -H 'Authorization: Bearer mwt_live_YOUR_KEY' \ -H 'Content-Type: application/json' \ -d '{"solve_for":"density","mass":1000,"volume":1,"mass_unit":"g","volume_unit":"L","density_unit":"g/cm3"}' ``` copy ```text import requests resp = requests.post( 'https://api.miniwebtool.com/v1/tools/density-calculator/run', headers={'Authorization': 'Bearer mwt_live_YOUR_KEY'}, json={'solve_for': 'density', 'mass': 1000, 'volume': 1, 'mass_unit': 'g', 'volume_unit': 'L', 'density_unit': 'g/cm3'}, ) resp.raise_for_status() print(resp.json()) ``` copy ```text const resp = await fetch( 'https://api.miniwebtool.com/v1/tools/density-calculator/run', { method: 'POST', headers: { 'Authorization': 'Bearer mwt_live_YOUR_KEY', 'Content-Type': 'application/json', }, body: JSON.stringify({"solve_for":"density","mass":1000,"volume":1,"mass_unit":"g","volume_unit":"L","density_unit":"g/cm3"}), } ); const data = await resp.json(); console.log(data); ``` copy ```text true, CURLOPT_RETURNTRANSFER => true, CURLOPT_HTTPHEADER => [ 'Authorization: Bearer mwt_live_YOUR_KEY', 'Content-Type: application/json', ], CURLOPT_POSTFIELDS => json_encode([ 'solve_for' => 'density', 'mass' => 1000, 'volume' => 1, 'mass_unit' => 'g', 'volume_unit' => 'L', 'density_unit' => 'g/cm3' ]), ]); $resp = curl_exec($ch); curl_close($ch); print_r(json_decode($resp, true)); ``` copy ```text require 'net/http' require 'json' require 'uri' uri = URI('https://api.miniwebtool.com/v1/tools/density-calculator/run') http = Net::HTTP.new(uri.host, uri.port) http.use_ssl = (uri.scheme == 'https') req = Net::HTTP::Post.new(uri) req['Authorization'] = 'Bearer mwt_live_YOUR_KEY' req['Content-Type'] = 'application/json' req.body = { 'solve_for' => 'density', 'mass' => 1000, 'volume' => 1, 'mass_unit' => 'g', 'volume_unit' => 'L', 'density_unit' => 'g/cm3' }.to_json resp = http.request(req) puts JSON.parse(resp.body).inspect ``` copy ```text package main import ( "bytes" "encoding/json" "fmt" "io" "net/http" ) func main() { body, _:= json.Marshal(map[string]interface{}{ "solve_for": "density", "mass": 1000, "volume": 1, "mass_unit": "g", "volume_unit": "L", "density_unit": "g/cm3", }) req, _:= http.NewRequest("POST", "https://api.miniwebtool.com/v1/tools/density-calculator/run", bytes.NewReader(body)) req.Header.Set("Authorization", "Bearer mwt_live_YOUR_KEY") req.Header.Set("Content-Type", "application/json") resp, err:= http.DefaultClient.Do(req) if err!= nil { panic(err) } defer resp.Body.Close() out, _:= io.ReadAll(resp.Body) fmt.Println(string(out)) } ``` copy ```text import java.net.URI; import java.net.http.*; var client = HttpClient.newHttpClient(); var req = HttpRequest.newBuilder() .uri(URI.create("https://api.miniwebtool.com/v1/tools/density-calculator/run")) .header("Authorization", "Bearer mwt_live_YOUR_KEY") .header("Content-Type", "application/json") .POST(HttpRequest.BodyPublishers.ofString("{\"solve_for\":\"density\",\"mass\":1000,\"volume\":1,\"mass_unit\":\"g\",\"volume_unit\":\"L\",\"density_unit\":\"g/cm3\"}")) .build(); var resp = client.send(req, HttpResponse.BodyHandlers.ofString()); System.out.println(resp.body()); ``` how-to call density-calculator - Get an API key [Get an API key](/billing/checkout/?plan=free). Sign up free for a bearer token. 1,000 credits/month, no card. - Assemble the JSON body Required fields:. See the Request body table above for the full schema. - POST to`https://api.miniwebtool.com/v1/tools/density-calculator/run` Headers:`Authorization: Bearer `and`Content-Type: application/json`. Copy-paste snippets in 7 languages are under Code examples. - Parse the response Envelope:`{request_id, tool, tool_version, credits_used, result}`. The typed output lives in`result`. faq frequently asked What does the Density Calculator API do? + Solve density, mass, or volume with common unit conversions. Use it to add this utility without rebuilding formulas, validation, examples, and documentation. How much does one call to Density Calculator cost? + 1 credit per successful call. Failed calls (validation errors, 5xx) don't bill. What parameters does the Density Calculator API require? + Required fields: (none). Full schema at /v1/openapi.json. Is the Density Calculator API deterministic? + Yes — same input, same output, forever. Tool version 2026-04-22; output shape is stable within a major version. Can an AI agent call the Density Calculator API? + Yes. Connect to https://api.miniwebtool.com/v1/mcp over the Model Context Protocol. The agent discovers `density-calculator` with its JSON Schema automatically, so the model can plan while MiniWebtool handles the exact tool result. What format does the API return? + JSON with a stable envelope: `{request_id, tool, tool_version, credits_used, result}`. Errors are RFC 7807 `application/problem+json`. mcp use from an AI agent Every endpoint on this site is also exposed via the [Model Context Protocol](/docs/#mcp) at`https://api.miniwebtool.com/v1/mcp`. Claude, Cursor, and any MCP-capable agent can discover this tool (`density-calculator`) and its JSON Schema automatically — no client codegen. ```text # List tools the agent can call curl -s https://api.miniwebtool.com/v1/mcp \ -H 'Content-Type: application/json' \ -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}' \ | jq '.result.tools[] | select(.name=="density-calculator")' ``` see-also related science tools [ psi to kPa Converter Convert pounds per square inch to kilopascals and related pressure units. ](/tools/psi-to-kpa-converter/) [ Bar to PSI Converter Convert bar and PSI, including kPa, MPa, atm, torr, inHg, and Pa. ](/tools/bar-to-psi-converter/) [ 555 Timer Calculator Calculate 555 timer astable frequency, period, duty cycle, or monostable pulse … ](/tools/555-timer-calculator/) [ Astronomical Unit Converter Convert astronomical distances among AU, light-time, parsecs, kilometers, and m… ](/tools/astronomical-unit-converter/) API OPERATIONAL v1 · OpenAPI 3.1 · MCP 2025-06-18 [terms](https://miniwebtool.com/about/terms-and-disclaimer/#api-terms) [privacy](https://miniwebtool.com/about/privacy/#api-privacy) [llms.txt](/llms.txt) [consumer site →](https://miniwebtool.com) © 2026 miniwebtool