Pipe volume calculator
A pipe 10 units long with radii 2 and 3 holds 125.6637061436 cubic units inside, and its wall uses 157.0796326795 of material. Enter inner radius, outer radius and length for plumbing take-offs, material orders or homework. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Inner
- 2
- Outer radius
- 3
- Length
- 10
- Wall thickness
- 1
- Annular area
- 15.7079632679
- Internal volume
- 125.6637061436
- Material volume
- 157.0796326795
This calculator turns a positive inner radius, outer radius, and axial length into the hollow-pipe volumes you need for plumbing take-offs, material estimates, and homework: the internal bore volume as pi times inner radius squared times length, the solid material volume as pi times the difference of outer and inner radius squared times length, the external cylinder volume, and the wall thickness as outer minus inner radius.
Three volumes in one hollow pipe
A straight pipe is a solid cylinder with a concentric hole running its full length. That gives three different volumes, and mixing them up is the usual source of wrong take-offs. The internal volume is the bore alone: pi times the inner radius squared times the length, which is how much water, air or fuel the run holds. The external volume is the whole outer cylinder as if it were solid. The material volume is the difference between the two, pi times the outer radius squared minus the inner radius squared, times the length, which is the steel, copper or plastic you actually buy and weigh.
Reading the results and avoiding mistakes
With an inner radius of 2, an outer radius of 3 and a length of 10, the wall is 1 unit thick, the bore holds 125.6637061436 cubic units and the wall takes 157.0796326795, which together make the 282.7433388231 of the outer cylinder. Enter radii, not diameters: halve a measured diameter first. The inner radius must be strictly smaller than the outer one, otherwise there is no wall and the calculator says so instead of returning a meaningless number. Keep all three lengths in the same unit, and choose how many decimals you want, ten by default.
What you can do with it
Homework and exam preparation
Compute hollow-pipe internal volume, material volume, and wall thickness from textbook inner radius, outer radius, and length, and verify that ri ≥ ro is rejected.
Pipe take-offs and material estimates
Size fluid capacity and steel or plastic wall volume for straight pipe runs in plumbing, HVAC, and manufacturing cut lists from known radii and length.
FAQ
What does the pipe volume calculator cost?
It is free in your browser on this page.
How is internal volume different from material volume?
Internal volume is the bore capacity V = π ri² L. Material volume is the solid wall V = π (ro² − ri²) L. External volume is the solid outer cylinder π ro² L.
Do I enter diameter or radius?
If you have diameters, divide each by two before calling, or convert in your client.
What happens if the inner radius is not smaller than the outer radius?
The calculator rejects it. With equal radii there is no wall, and a bigger inner radius describes no real pipe, so you get a clear message instead of a negative or empty material volume.
What is the external volume of a pipe?
It is the volume of the outer cylinder as if the pipe were solid. It always equals the internal volume plus the material volume, which makes it a quick check on the other two results.
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/geom/pipe-volume \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"inner_radius":2,"outer_radius":3,"length":10}'const res = await fetch("https://api.kit.forhosting.com/geom/pipe-volume", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"inner_radius": 2,
"outer_radius": 3,
"length": 10
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/geom/pipe-volume",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"inner_radius": 2,
"outer_radius": 3,
"length": 10
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/geom/pipe-volume", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"inner_radius":2,"outer_radius":3,"length":10}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"inner_radius":2,"outer_radius":3,"length":10}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/geom/pipe-volume", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"inner_radius": 2,
"outer_radius": 3,
"length": 10
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "geom.pipe_volume",
"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
You enter three finite positive lengths with the inner radius strictly below the outer radius; the engine returns those inputs plus wall_thickness, annular_area, internal_volume, material_volume, external_volume, and formula strings so a student or a log line can verify the identity without reading the source. When a radius or length is missing, zero, negative, non-finite, or the inner radius is not below the outer radius, the tool returns invalid_input instead of a silent NaN. Through the API a successful request costs $0.002; validation failures are not charged.
What a pipe volume calculator returns and why both radii matter
A straight hollow circular pipe is an annular cylinder: a solid outer cylinder of radius ro with a concentric cylindrical hole of radius ri along the full axial length L. This tool exists to turn those three positive lengths into a single deterministic response without forcing you to remember whether capacity uses the inner radius only, whether material volume subtracts the bore from the outer solid, or how wall thickness relates to the two radii. If you need cone volume, torus volume, or a solid cylinder only, use a tool dedicated to those problems; the search intent here is the hollow pipe from inner and outer radius and length, with a clear answer or an honest error when the geometry is not a valid annular cylinder. The response always echoes inner_radius, outer_radius, and length, reports wall_thickness as outer minus inner, annular_area as pi times the difference of the squared radii, internal_volume as pi ri squared L, material_volume as pi times that annular area times L, external_volume as pi ro squared L, and formula strings for the three volumes and the thickness so a student or a log line can verify the identity without reading the source. Missing any required field, non-finite values, a non-positive dimension, or an inner radius that is not strictly below the outer radius all raise invalid_input with a message that names the failing constraint. That discipline keeps automated tests stable, makes caching safe, and prevents a script from treating a solid rod or an inverted shell as a real pipe.
How the closed forms are evaluated: internal, material, and external volume
Internal volume is the exact fluid capacity of the bore: pi times inner radius squared times length, independent of the outer shell. Material volume is the solid annular wall: pi times the difference of outer radius squared and inner radius squared times length, which is exactly the external solid cylinder minus the internal cylinder. Optional precision only rounds the published fields; the internal solve always uses full double precision before that final rounding step. The engine resolves inner_radius from the field inner_radius with aliases ri, r_inner, and inner_r, outer_radius from outer_radius with aliases ro, r_outer, and outer_r, and length from length with aliases L, height, and h, requiring each to be finite and strictly greater than zero, then requires inner_radius to be strictly less than outer_radius so the wall has positive thickness. External volume is the solid cylinder of radius outer_radius and the same length, useful when you need the envelope volume for packing or clearance. Wall thickness is the simple difference outer minus inner, and annular_area is the cross-sectional area of material in a plane perpendicular to the axis. Pair the free browser run on this page with the priced API when you need the identical mathematical result inside an automated pipeline without re-implementing the annular cylinder formulas yourself.
Where pipe volumes fit in study, design, and code
Students meet the hollow pipe when a textbook asks for the volume of material in a tube, when an exam demands fluid capacity from inner diameter and length, or when solid-geometry homework wants both the bore and the wall so material cost and flow capacity stay distinct. Teachers can pre-generate answer keys that list internal and material volumes for integer radii and lengths, and that refuse zero thickness or inverted radii instead of printing NaN. Mechanical and civil design often needs the steel or plastic volume of a pipe run for weight and cost, the water capacity of a segment for storage and pressure tests, or the external envelope for trench and sleeve sizing; knowing that a requested inner radius is not below the outer radius is as valuable as the number itself. Plumbing take-offs, HVAC duct work that models circular tubes, and manufacturing cut lists for seamless tubing all benefit from a single contract that returns both volumes and wall thickness together. On this page the work runs entirely in your browser; through the API each successful lookup costs $0.002, failed validation is not charged, and nothing is stored after the response returns. That split—free interactive exploration and a priced, identical API—matches the rest of the KIT tier-A catalog and lets you move from a classroom demo to an automated pipeline without changing the mathematical result. Pair it with other free geometry endpoints when you need cone, torus, or pyramid solvers for a lab of deterministic tools, and with documentation that shows both radii, the length, and the finished volumes so the numbers and the picture stay aligned for learners and reviewers. Whether you arrived searching for a pipe volume calculator or for internal and material volume from inner and outer radius, the contract is the same: positive radii and length with inner strictly below outer in, finite metrics or a clear invalid_input out.
Integration use cases
Deterministic geometry fixtures
Generate reproducible annular-cylinder metrics for unit tests, contest validators, and CI assertions without hand-rolled bore and wall volume logic.
Technical questions
What if the inner radius is not below the outer radius?
The handler returns invalid_input with a message that inner_radius must be strictly below outer_radius (hollow pipe requires ri < ro).
Can I control rounding?
Yes. Set precision (aliases decimals, dp) to an integer from 0 to 15; the default is 10 decimal places on all numeric fields.