Roof pitch converter
Translate one roof pitch into the other notations: a 6/12 roof is about 26.57 degrees and a 50 % slope, so framing plans, inspection notes and drainage specs describe the same plane. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Value
- 6
- Unit of 'value': rise
- Rise
- Rise
- 6
- Rise in 12
- 6/12
- Run
- 12
- Degrees
- 26.56505118
Roof pitch is the same physical slope written three different ways: framing crews say six-in-twelve, inspectors and architects often quote degrees from horizontal, and drainage or accessibility notes prefer a percentage grade. Mixing those notations by hand is easy to get wrong because the relationships use the tangent of the roof angle, not a simple linear scale. This roof pitch converter takes one non-negative pitch in rise-in-12, degrees, or percent slope and returns the full set of equivalents with a fixed twelve-unit run, plus radians and the unitless rise-over-run ratio for CAD and spreadsheet pipelines. Negative rise values are rejected with a clear invalid input error so inverted planes never look like a valid roof schedule.
Rise-in-12, degrees, and percent slope — what each notation means
Start from the form of pitch you already have. In North American carpentry, rise-in-12 means how many inches the roof climbs for every twelve inches of horizontal run: a six-in-twelve roof rises six inches over a one-foot run and is written 6/12 on plans and package labels. Degrees measure the angle of the roof plane above horizontal, so the same six-in-twelve pitch is about twenty-six point five seven degrees because the tangent of that angle equals six divided by twelve.
Percentage slope multiplies the unitless rise-over-run ratio by one hundred, so six over twelve is a fifty percent slope—useful for drainage specs, ramp notes, and some European listings that never say X-in-12. Send the required field value as a finite number and set from to rise, degrees, or percent; if you omit from, rise-in-12 is assumed because that is the default trade notation for this product.
You may also pass a string such as six slash twelve when from is rise; the engine normalizes any rise-over-run pair onto a twelve-unit run. Choose the notation that matches your source drawing, then read the other two fields for cross-team handoff without reopening a calculator app.
How the conversion works and how to read the response
All three notations share one geometric model: a right triangle with horizontal run and vertical rise. With run fixed at twelve for the rise-in-12 convention, the unitless slope is rise divided by twelve, which also equals tan of the roof angle in radians and equals percent divided by one hundred. From a rise input the engine computes degrees with arctangent and percent with a simple scale factor.
From degrees it multiplies twelve by the tangent of the angle after converting degrees to radians, then derives percent. From percent it recovers rise as twelve times percent over one hundred and degrees via arctangent. Flat roofs are valid: rise zero maps to zero degrees and zero percent.
Degrees must stay in the half-open range from zero inclusive to ninety exclusive; ninety degrees is vertical and would make the rise infinite.
What you can do with it
Framing schedules and truss orders
Convert a 6/12 package label into degrees and percent for inspectors, or turn a degree callout on an architect sheet into rise-in-12 for the lumber yard.
Drainage grades and ramp notes
Civil percent grades and accessibility ramp slopes convert cleanly into roof-style rise-in-12 or degrees when mixed building documents share one slope model.
FAQ
What happens if the rise is negative?
Negative rise values are not allowed for roof pitch; use a non-negative rise-in-12, non-negative percent, or degrees in [0, 90).
Can I enter degrees or percent instead of rise-in-12?
Yes. Set from to "degrees" or "percent" and pass the matching value. The engine returns all three notations from whichever one you supply.
Is the roof pitch converter free?
The browser tool runs free on your device.
What is the difference between percent slope and degrees?
Percent slope is 100 times rise over run (linear ratio). Degrees are the arctangent of that same ratio. They are not interchangeable as equal numbers: a 100% slope is 45 degrees, not 100 degrees.
What pitch is a 45-degree roof?
A 45-degree roof is a 12-in-12 pitch, also written 12/12, and a 100 % slope, because the rise equals the run. It is the point where percent slope reaches one hundred.
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/roof-pitch \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"value":6}'const res = await fetch("https://api.kit.forhosting.com/conv/roof-pitch", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"value": 6
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/conv/roof-pitch",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"value": 6
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/conv/roof-pitch", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"value":6}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"value":6}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/conv/roof-pitch", 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": 6
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "conv.roof_pitch",
"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.
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
Rise-in-12, degrees, and percent slope — what each notation means
Identical inputs always produce identical JSON because the path is pure trigonometry with no network, no random seed, and no wall clock.
How the conversion works and how to read the response
On success the response echoes value and from, then rise, rise_in_12 as a human label such as 6/12, run always twelve, degrees, radians, percent, and slope_ratio for the unitless grade. The formula string restates the tangent identities for audit logs, and method is always roof_pitch_trig so downstream code can branch without sniffing shapes. Missing value, non-finite numbers, unknown from tokens, degrees outside that range, and any path that yields a negative rise all fail with invalid_input and are not charged after the engine rejects the request.
API usage, pricing, field workflows, and practical limits
Call the free in-browser roof pitch converter when you are reading a truss schedule, checking a permit sketch, or converting a percent grade from a civil note into framing language without installing a spreadsheet. Remember that marketed pitch describes the plane of the sheathing or rafter, not decorative eave returns or stepped parapets, so leave room for local code minimums when applying a converted degree value on site. Authors shipping SDKs can map rise, degrees, and percent into side-by-side tables that match how inspectors, framers, and drainage engineers each talk about the same slope. Send a JSON body with the required finite value and optional from defaulting to rise. Use the prepaid API when a roofing estimator, building-permit portal, material takeoff service, or accessibility ramp calculator needs a stable contract under KIT balance at $0.002 per successful item; validation failures never consume balance after the engine rejects the request. Pair this endpoint with length and area tools when you next need rafter length or roof surface area from pitch and plan footprint, or with general unit converters when drawings mix imperial and metric linear dimensions.
Integration use cases
Permit portals and roofing estimators
Permit apps and takeoff tools call the prepaid API so every pitch field stores rise, degrees, and percent without maintaining separate spreadsheet formulas per jurisdiction.
Technical questions
How do I convert a 6/12 roof pitch to degrees?
Send JSON with value: 6 and from: "rise" (or omit from). The response includes degrees (about 26.565) and percent (50) along with the rise_in_12 label "6/12".