Miter saw angle calculator
A square 90-degree corner needs 45 on the saw table and 45 on the blade; a 135-degree bay needs 22.5 and 67.5. Enter the wall angle you measured and cut both trim pieces to meet on the bisector. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Corner angle
- 90
- Miter angle
- 45 deg
- Blade angle
- 45
- Turn angle
- 90
- Corner kind
- inside
Finish carpenters, remodelers, millwork shops, and weekend builders measure the included wall angle with a protractor or a digital angle finder, then need both settings in degrees before they commit a stick of baseboard, casing, chair rail, or picture moulding. This angle-cut calculator takes that single corner angle, bisects the corner, and returns the miter-saw table setting together with the complementary blade angle so two pieces meet on the bisector. A square inside corner of 90 degrees yields 45 and 45; an obtuse 135-degree corner yields 22.5 degrees of miter and 67.5 degrees of blade. A square outside corner entered as 270 degrees yields the same 45 and 45 pair, because the saw still bisects a 90-degree turn.
How miter and blade angles are computed from a corner
A corner in finish carpentry is the included angle between two walls, measured in degrees on the room side of the trim. Two pieces of flat stock such as baseboard or casing meet on the bisector of that corner, so each piece carries half of the wall's turn. A miter saw does not read that half-corner directly.
Its table scale reads zero when the blade is square to the fence, which is a ninety-degree cut on the stock, and it counts how far you swing away from that square. The swing you need is therefore half of how far the wall itself turns away from a straight one-hundred-eighty-degree run.
In symbols the turn angle is the absolute value of one hundred eighty minus the corner angle, the miter angle is that turn divided by two, and the blade angle left on each piece is ninety minus the miter angle. For a square inside corner of ninety degrees the turn is ninety, the miter setting is forty-five, and the blade angle on the stock is forty-five.
For an obtuse inside corner of one hundred thirty-five degrees the turn is forty-five, the miter setting is twenty-two point five, and the blade angle is sixty-seven point five. For a square outside corner entered as two hundred seventy degrees the absolute-value turn is again ninety, so the saw still reads forty-five and forty-five. A straight wall of one hundred eighty degrees is a square cut: miter zero, blade ninety.
The two returned settings always sum to ninety degrees, which is the identity that lets you set the table and still reason about the remaining wood. This calculator does not take a crown-moulding spring angle and does not emit a compound bevel for stock stood on its edge; those are two-input problems.
Where a miter-saw angle calculator earns its keep
Out-of-square rooms are the daily case: a corner that measures 93 degrees is not a 45-degree miter, and cutting 45 anyway leaves a wedge gap in the baseboard that caulk cannot honestly hide. Casing around doors and windows, chair rail, picture moulding, and wainscot cap all use the same bisect, so one corner reading feeds every stick that turns that wall.
Bay windows and polygonal rooms produce obtuse insides near 135 degrees; the calculator returns 22.5 on the table and 67.5 on the stock so both pieces of the bay meet without sneaking a different angle onto each side. Outside corners entered as 270 degrees keep the same 45 and 45 pair as a square inside, which matches how an angle finder reports the long way around the plaster. Curriculum authors and LMS auto-graders pin goldens: ninety must stay forty-five and forty-five.
The tool is a planar miter of flat trim, not a substitute for coping an inside joint, for a crown spring-angle compound chart, or for scribing irregular plaster. If you later need stick counts, paint coverage, or a two-input compound bevel, treat those as separate search intents rather than overloading this angle-cut page.
What you can do with it
Bay windows and polygonal trim runs
Obtuse insides near 135 degrees return 22.5 degrees of table miter and 67.5 degrees of blade, the pair shops use on bay casings and hexagonal frames.
Outside corners from a 270-degree reading
An angle finder that reports the long way around a square outside corner as 270 degrees still yields 45 and 45, the same saw settings as a square inside.
FAQ
My corner is not 90 degrees. What do I set on the saw?
Measure the true included angle and send it. Cutting 45 degrees on an out-of-square wall leaves a gap.
How do I enter an outside corner?
Send the included angle the long way around, typically 270 degrees for a square outside. The absolute turn is still 90 degrees, so the saw settings stay 45 and 45.
What miter setting does a straight 180-degree wall need?
None: the miter is 0 and the blade angle is 90, which is a plain square cut. A straight run does not turn, so there is no corner to split between two pieces.
Why do the miter and blade angles always add up to 90 degrees?
Because the saw table reads zero at a square cut and the blade angle is what remains of that right angle on the stock. A 22.5 miter leaves 67.5 on the blade, and 45 leaves 45.
Does this work for crown moulding?
No. Crown stood on its edge needs a spring angle and a compound bevel, which take two inputs. This calculator handles flat stock such as baseboard, casing, chair rail and picture moulding.
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/build/angle-cut \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"corner_angle":90}'const res = await fetch("https://api.kit.forhosting.com/build/angle-cut", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"corner_angle": 90
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/build/angle-cut",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"corner_angle": 90
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/build/angle-cut", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"corner_angle":90}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"corner_angle":90}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/build/angle-cut", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"corner_angle": 90
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "build.angle_cut",
"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
min_deg | 0 |
max_deg | 360 |
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
A miter saw has two numbers that matter when trim turns a corner: the table miter and the blade angle left on each piece. Corner angles that are not between 0 and 360 degrees fail with invalid_input and are not billed.
How miter and blade angles are computed from a corner
It is the one-input bisect of a measured corner into a miter-saw table setting and a complementary blade angle, rounded to twelve decimal places so goldens, widgets, and API clients never disagree on a 22.5-degree cut.
What you send, which units to use, and how validation fails
The value must be between 0 and 360 degrees inclusive; a square inside corner is 90, a straight wall is 180, and a square outside corner is 270. Degrees are the only unit: do not send radians, gradians, or a turn in [0, 1]. Failed tasks are not billed. Upper and lower limits are the closed degree interval itself: below 0 or above 360 is never a corner a saw can bisect, and non-finite values are rejected before any arithmetic. The same input always produces the same rounded output, which is the contract homework checkers, estimating sheets, and edge workers rely on when they pin a 135-degree bay as 22.5 and 67.5. Send one required numeric field named corner_angle: a finite number of degrees for the included wall angle. Aliases angle, corner, and wall_angle are accepted so a form that already says angle does not need a rename. Strings that parse as finite numbers are accepted the same as JSON numbers. On success the response echoes the cleaned corner_angle, publishes miter_angle as the table setting, blade_angle as the complementary cut on the stock, turn_angle as the absolute wall turn, corner_kind as inside, straight, or outside, unit as deg, and formula as the two-line identity miter_angle equals the absolute value of 180 minus corner_angle, all over 2, and blade_angle equals 90 minus miter_angle. A ninety-degree corner yields miter_angle 45, blade_angle 45, turn_angle 90, and corner_kind inside. A four-hundred-degree reading, a negative angle, or a missing field fails with invalid_input naming corner_angle so a form can highlight that control. Successful API calls use the published base of $0.002 per item.
Where a miter-saw angle calculator earns its keep
Picture-frame and box-frame shops that join N pieces around a regular polygon can still use this page one corner at a time, because a regular N-gon interior is 180 times (N minus 2) over N, and that single number is the corner_angle.
Integration use cases
Baseboard and casing on out-of-square walls
Measure the included corner, send it as corner_angle, and set the miter saw to miter_angle so two pieces of baseboard or casing close without a wedge gap.
Technical questions
How do I calculate miter saw blade and miter angles from a corner?
Send the included corner_angle in degrees (0 to 360). The API returns miter_angle = |180 − corner_angle| / 2 and blade_angle = 90 − miter_angle, both in degrees.
What is the difference between miter_angle and blade_angle?
miter_angle is the table setting on a saw that reads 0° at a square cut. blade_angle is the complementary cut left on each piece of stock. They always sum to 90 degrees.
What does the angle cut calculator cost, and what if the angle is out of range?
The browser tool is free. API requests use prepaid KIT balance at $0.002 per successful call. A corner_angle that is not between 0 and 360 degrees fails with invalid_input and is not billed.