Physical Constants

Name: Physical Constants
Creator: staticdata.dev
License: https://opensource.org/licenses/MIT

A complete listing of fundamental physical constants from the NIST CODATA 2022 adjustment, including well-known quantities such as the speed of light, Planck constant, elementary charge, Boltzmann constant, and Avogadro constant, as well as derived relationships and particle properties.

v1.0.0 MIT 355 records Updated 2026-10-05 stable Source: NIST CODATA 2022 Fundamental Physical Constants

Quick fetch

Stable URL. CORS-enabled. No auth.

bash

curl https://staticdata.dev/v1/physical-constants.json

Or use as a typed import: import { physicalConstants } from "https://staticdata.dev/v1/physical-constants.ts"

Formats

JSON 47.9 KB

/v1/physical-constants.json

Open

min: 37.5 KB · /v1/physical-constants.min.json
CSV 21.7 KB

/v1/physical-constants.csv

Open
TypeScript 48.1 KB

/v1/physical-constants.ts

export const physicalConstants

type PhysicalConstant = (typeof physicalConstants)[number]

Open

Schema

Each record in the dataset has the following shape.

Schema
Field	Type	Description	Example
name	string	Full NIST name of the constant	speed of light in vacuum
value	string	Numeric value as a string preserving full precision (may include e-notation or trailing ...)	299792458
uncertainty	string	Absolute uncertainty as a string, or '(exact)' for defined values	(exact)
unit	string \| null	SI unit string, or null for dimensionless quantities	m s^-1

Preview

First 10 records.

Data preview
name	value	uncertainty	unit
alpha particle mass	6.6446573450e-27	0.0000000021e-27	kg
alpha particle mass energy equivalent	5.9719201997e-10	0.0000000019e-10	J
alpha particle mass energy equivalent in MeV	3727.3794118	0.0000012	MeV
alpha particle mass in u	4.001506179129	0.000000000062	u
alpha particle molar mass	4.0015061833e-3	0.0000000012e-3	kg mol^-1
alpha particle relative atomic mass	4.001506179129	0.000000000062
alpha particle rms charge radius	1.6785e-15	0.0021e-15	m
alpha particle-electron mass ratio	7294.29954171	0.00000017
alpha particle-proton mass ratio	3.972599690252	0.000000000070
Angstrom star	1.00001495e-10	0.00000090e-10	m

Showing 10 of 355. View full data: JSON · CSV

Fetch examples

Drop-in snippets in five languages.

curl

curl -sSL https://staticdata.dev/v1/physical-constants.json | jq '.[0]'

JavaScript

import type { PhysicalConstant } from "https://staticdata.dev/v1/physical-constants.ts";

const res = await fetch("https://staticdata.dev/v1/physical-constants.min.json");
if (!res.ok) throw new Error(`Fetch failed: ${res.status}`);
const physicalConstants: PhysicalConstant[] = await res.json();
console.log(physicalConstants[0]);

Python

import urllib.request, json

with urllib.request.urlopen("https://staticdata.dev/v1/physical-constants.min.json") as r:
    physicalConstants = json.load(r)

print(physicalConstants[0])

package main

import (
	"encoding/json"
	"fmt"
	"net/http"
)

func main() {
	resp, err := http.Get("https://staticdata.dev/v1/physical-constants.min.json")
	if err != nil { panic(err) }
	defer resp.Body.Close()

	var data []map[string]any
	if err := json.NewDecoder(resp.Body).Decode(&data); err != nil {
		panic(err)
	}
	fmt.Println(data[0])
}

Rust

use serde_json::Value;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let body = ureq::get("https://staticdata.dev/v1/physical-constants.min.json").call()?.into_string()?;
    let data: Vec<Value> = serde_json::from_str(&body)?;
    println!("{:?}", data.first());
    Ok(())
}

Sources and methodology

This dataset contains all 355 fundamental physical constants from the NIST Committee on Data for Science and Technology (CODATA) 2022 recommended values, published at physics.nist.gov. CODATA adjustments are performed periodically by the Task Group on Fundamental Constants to incorporate the latest precision measurements across atomic, nuclear, and particle physics.

Values are stored as strings to preserve full precision, including cases where NIST appends ... to indicate that additional digits exist beyond what is shown. Uncertainties are similarly stored as strings; the token (exact) denotes quantities that are defined with zero uncertainty under the 2019 SI revision (e.g., the speed of light, Planck constant, and elementary charge). Dimensionless ratios and pure numbers have a null unit field.

The dataset covers particle masses and mass ratios (electron, proton, neutron, muon, tau, deuteron, helion, triton, alpha particle), magnetic moments, gyromagnetic ratios, unit conversion relationships (joule, kelvin, hertz, electron volt, hartree, kilogram, inverse meter, and atomic mass unit to each other), Planck-scale quantities, and thermodynamic and electromagnetic constants. Names follow the NIST convention exactly, enabling unambiguous cross-reference to the source table.

Versioning

URLs under /v1/ are stable: field names and types will not change in a way that breaks consumers. Values can be corrected or records added when the upstream source changes; schema-incompatible updates ship under a new version path. See the physical-constants changelog for this dataset's history.