Calculate gravel volume for a driveway and estimate its weight
120 square metres of driveway at a depth of 5 cm need 6 cubic metres of gravel, about 9.6 tonnes. Enter your area and finished depth to check a quote or a contractor's estimate before ordering. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Area m2
- 120
- Depth cm
- 5
- Depth m
- 0.05
- Standard density kg m3
- 1,600
- Volume m3
- 6
- Estimated weight kg
- 9,600
Use this driveway gravel calculator when you know the surface area to cover and the finished gravel depth you want. Enter the area in square metres and the depth in centimetres. The calculator converts the depth to metres, computes the required volume in cubic metres, and estimates the material weight in kilograms and metric tonnes using a standard bulk density of 1,600 kilograms per cubic metre. The result is a practical baseline for planning an order, comparing supplier quotes, or checking a contractor's material estimate before allowing for site-specific waste and compaction.
Measure the driveway area and choose a finished depth
Start with the horizontal surface area that the gravel will cover. For a rectangular driveway, multiply its length by its width, using metres for both measurements so the result is in square metres. Divide an irregular driveway into simple rectangles, calculate each section, and add the areas together.
Measure only the part receiving gravel; exclude planting beds, drains, paved aprons, and other uncovered sections. Next, choose the desired finished depth in centimetres. The finished depth is the thickness you want after the material has been spread and settled, not the height of a loose pile delivered beside the driveway.
A thin decorative refresh and a new load-bearing driveway layer have different construction needs, so the appropriate depth should come from the project specification or local professional advice. The calculator requires a depth greater than zero because a zero or negative thickness cannot represent a gravel layer. It also requires a positive area.
Accurate inputs matter more than extra decimal places: measure several widths where the driveway varies, and use the total area rather than relying on a single rough length-by-width estimate.
Understand the volume and standard weight calculation
The volume calculation is straightforward once the units are consistent. The calculator divides the entered depth in centimetres by one hundred to obtain metres, then multiplies the driveway area in square metres by that depth in metres. The result is cubic metres of gravel.
To estimate weight, it multiplies the volume by a standard bulk-density factor of 1,600 kilograms per cubic metre. For example, an area of 120 square metres at a depth of 5 centimetres becomes 0.05 metres deep, needs 6 cubic metres of material, and has an estimated weight of 9,600 kilograms, or 9.6 metric tonnes. Bulk density describes a volume of loose aggregate including the spaces between stones; it is not simply the mineral density of solid rock.
Actual density varies with stone type, grading, moisture, and how the load is handled. Treat the weight as an informed estimate for early planning. If a quarry or merchant publishes a density or conversion factor for the exact gravel product, use that supplier information to refine the order outside this standard-factor calculation.
Turn the estimate into a practical gravel order
Use the returned cubic metres and estimated tonnes as the clean geometric baseline for a conversation with the supplier. Real driveways may need more material because the prepared base is uneven, edges are wider than the survey suggests, aggregate settles into the sub-base, or some stone is lost during transport and spreading. This calculator deliberately does not add a hidden waste or compaction percentage, so you can see the underlying quantity and apply a project-specific allowance transparently.
Ask whether the supplier sells by loose cubic metre, metric tonne, bulk bag, or another unit, and confirm whether the quoted conversion already accounts for the product's typical moisture and grading. Do not assume that the standard density makes every gravel product interchangeable. Also check vehicle access, delivery weight limits, and whether one large load or several smaller loads are practical.
Invalid entries, including a depth that is zero or negative, return an input error rather than an impossible material quantity. Keep the input and result with your estimate so later changes in area or specified depth can be recalculated consistently.
What you can do with it
Plan a new driveway surface
Convert the measured driveway area and specified gravel depth into cubic metres and an estimated delivery weight before requesting supplier quotes.
Check a contractor estimate
Compare a proposed gravel quantity with a transparent area-times-depth calculation and a clearly stated standard density factor.
Recalculate after a design change
Quickly update material volume and weight when the driveway footprint or desired finished layer depth changes.
FAQ
What density does the calculator use?
It uses a standard bulk-density factor of 1,600 kilograms per cubic metre. Actual gravel density varies, so use a product-specific supplier figure when available.
What units should I enter?
Enter driveway area in square metres and desired gravel depth in centimetres. The results are cubic metres, kilograms, and metric tonnes.
Does the result include waste or compaction?
No. It returns the geometric volume and a standard-density weight estimate. Add an allowance appropriate to the site and supplier separately.
How much gravel do I need for 120 square metres at 5 cm?
Six cubic metres. The 5 cm depth becomes 0.05 m, and 120 times 0.05 gives the volume. At 1,600 kilograms per cubic metre that is about 9,600 kg, or 9.6 tonnes.
How do I measure an irregular driveway?
Split it into simple rectangles, multiply length by width for each one and add the areas. Measure several widths where the driveway varies, and leave out beds, drains and paved parts that get no gravel.
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/gravel-volume-calculate \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"area_m2":120,"depth_cm":5}'const res = await fetch("https://api.kit.forhosting.com/build/gravel-volume-calculate", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"area_m2": 120,
"depth_cm": 5
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/build/gravel-volume-calculate",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"area_m2": 120,
"depth_cm": 5
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/build/gravel-volume-calculate", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"area_m2":120,"depth_cm":5}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"area_m2":120,"depth_cm":5}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/build/gravel-volume-calculate", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"area_m2": 120,
"depth_cm": 5
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "build.gravel_volume_calculate",
"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
Turn the estimate into a practical gravel order
The API costs $0.002 per successful request and uses the same deterministic calculation as the browser tool.
Technical questions
Why must the depth be positive?
A zero or negative depth cannot describe a physical gravel layer, so the calculator returns an invalid_input error for those values.
How much does an API calculation cost?
Each successful API request costs $0.002. The browser calculator uses the same deterministic formula.