Electric field strength converter
One volt per mil is about 39370 volts per metre, because a mil is a thousandth of an inch. Convert field strength between V/m, V/cm, kilovolts per metre and volts per mil, so insulation ratings, clearance rules and homework share one scale. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Value
- 1,000
- From
- V/m
- To
- V/cm
- Result
- 10 V/cm
- Converted
- 10
- Value vpm
- 1,000
- Factor
- 0.01
An electric field strength converter turns one field-intensity magnitude into another common engineering unit without spreadsheet formulas or mental scale tables. Enter a finite value plus a source unit and a target unit among volts per meter, volts per centimeter, kilovolts per meter, and volts per mil; the tool returns the converted field strength, the SI intermediate in V/m, the exact unit factor applied, and step-by-step substitution lines you can paste into a lab notebook or design review. Insulation and high-voltage engineers scaling breakdown ratings, PCB and cable designers comparing V/mil creepage rules, students converting homework field values, and instrumentation authors mapping sensor ranges to SI all need the same deterministic path.
Which electric field units are supported and how conversion works
This capability converts among four everyday electric field strength units that dominate high-voltage engineering, insulation design, electrostatics coursework, and North American mil-based rules of thumb. The volt per meter (V/m) is the SI coherent unit and the internal hub: every conversion multiplies the input by how many V/m equal one source unit, then divides by how many V/m equal one target unit. Volts per centimeter use the exact geometric factor of one hundred: one centimeter is one hundredth of a meter, so one V/cm equals one hundred V/m.
Kilovolts per meter use the exact SI kilo prefix of one thousand volts per meter. Volts per mil use the exact inch definition of the mil as one thousandth of an inch, which is two point five four times ten to the minus five meters, so the factor to SI is the reciprocal of that length. Same-unit requests succeed and return the input magnitude with a short message that no change of unit was required.
What you can do with it
PCB and cable creepage in V/mil
Designers convert North American volts-per-mil rules into SI V/m or V/cm for global documentation, clearance checks, and simulation inputs.
FAQ
How is one volt per mil defined?
One mil is exactly one thousandth of an inch, or 2.54×10⁻⁵ meters. The converter uses that exact length so V/mil maps deterministically to SI V/m.
Is the electric field strength converter free?
The browser tool is free and runs locally.
How many V/m is one V/cm?
One volt per centimetre is 100 volts per metre, because a centimetre is a hundredth of a metre. That is why 1000 V/m reads as 10 V/cm.
Where are volts per mil used?
Mostly in North American insulation, circuit-board and cable rules for creepage and breakdown ratings. Converting them to volts per metre or per centimetre lets you use the same figure in global documents, clearance checks and simulations.
Can I enter a negative field strength?
Yes. A negative value keeps its sign for work with directed fields, and the converter scales it exactly as it would a positive value.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/conv/electric-field \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"value":1000,"from":"V/m","to":"V/cm"}'const res = await fetch("https://api.kit.forhosting.com/conv/electric-field", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"value": 1000,
"from": "V/m",
"to": "V/cm"
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/conv/electric-field",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"value": 1000,
"from": "V/m",
"to": "V/cm"
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/conv/electric-field", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"value":1000,"from":"V/m","to":"V/cm"}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"value":1000,"from":"V/m","to":"V/cm"}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/conv/electric-field", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"value": 1000,
"from": "V/m",
"to": "V/cm"
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "conv.electric_field",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Limits
max_abs | 1000000000000 |
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
Unknown unit names fail with a clear invalid_input error instead of silent wrong factors.
Which electric field units are supported and how conversion works
If the name is not on that list the solver rejects the request with invalid_input naming the bad field and listing supported units, so clients never guess whether a typo produced a wrong number. Negative field values are allowed for signed directed-field contexts; absolute magnitude must stay within the published one-trillion limit so intermediate products remain finite in IEEE double precision on the Worker and in the browser.
How to call the API and read the response
Value must be a finite number or a strict numeric string within absolute limits of one trillion. Wire this into dashboards, mobile clients, or batch jobs that already hold a field-strength reading and only need a second unit for display, standards comparison, or homework checking without shipping floating conversion tables in every app binary. Send a JSON body with three required fields: value (aliases field, amount, e, and strength), from (aliases from_unit, unit_from, and source), and to (aliases to_unit, unit_to, and target). From and to must resolve to supported unit names after alias normalization. On success the response echoes the rounded input value, canonical from and to labels, result and converted set to the same rounded target magnitude, value_vpm as the SI intermediate in volts per meter, unit as the target label, factor as from-to multiplier, formula as the short equation string, message as an English summary, steps as ordered substitution lines, and supported_units as the four canonical identifiers. Failed validation—missing fields, non-finite numbers, values outside absolute limits, or an unknown unit name—returns invalid_input and is never charged. Pricing is a flat $0.002 per successful request with unit item and zero marginal unit price.
Practical tips, limits, and when to use this landing
Prefer sending bare numbers for value when you control the client; string numbers are accepted only when they match a strict finite numeric pattern without currency symbols or thousand separators. Round-trip checks are straightforward: convert A to B and B back to A and confirm you recover the original within the published twelve-decimal rounding. Stay inside the absolute range so intermediate V/m values cannot overflow. Prefer this capability when both endpoints are among the four supported field-strength units and you need deterministic factors and step strings; if you need force from charge and field, use the dedicated electric field force calculator instead. Failed tasks that return invalid_input do not consume prepaid balance, which keeps exploratory scripts cheap when clients deliberately probe unknown unit names.
Integration use cases
Insulation and breakdown rating notes
High-voltage and materials teams convert V/m, kV/m, and V/cm breakdown or withstand figures so datasheets, lab reports, and mixed-unit standards stay consistent.
Homework and lab field checks
Students convert V/m, V/cm, and kV/m homework values with deterministic steps they can compare against hand calculations before submission.
Technical questions
Which electric field strength units can I convert?
Volts per meter (V/m), volts per centimeter (V/cm), kilovolts per meter (kV/m), and volts per mil (V/mil), including common full-word aliases such as volts per meter and kilovolts per meter.
What happens if I send an unknown unit name?
The API returns invalid_input, names the bad field, and lists the supported units. The failed task is not charged.
Are results deterministic across browser and API?
Yes. Handler and widget share the same lib.js solve path with fixed geometric and SI factors and twelve-decimal rounding, so golden examples match production.