About Us
About the Steel Plate Weight Calculator
This site exists to answer one question quickly and defensibly: what does that plate weigh? It is free, runs entirely in your browser, and shows the working rather than handing back a number you have to take on trust.
Who we are
The Steel Plate Weight Calculator is an independent tool. It is not attached to a mill, a stockholder or a software vendor, and nothing on it is placed to move you toward a supplier. That independence is the point: an estimating tool that quietly favours somebody is worse than no tool at all.
It is funded by advertising and nothing else. There is no paid tier, no account, no export you have to unlock, and no mailing list standing between you and a result. We do not sell data because we do not collect it, and the calculation never leaves your device.
The work
How the site is maintained
Three things need keeping honest, and each is checked against the others before anything ships.
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The calculation engine
Geometry and units
One module handles every shape and every unit conversion, and the same module runs on the server at build time and in your browser. That is why the drawing, the formula line and the total can never disagree with each other.
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The density library
Reference data
37 densities across 5 material families, each traceable to a published standard or a standard reference work. When a source is rounded rather than grade-specific, the article that uses it says so.
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The written guides
Editorial
Every worked example in the blog is computed and checked against the calculator before it is published, so a number in an article and a number on the tool are the same number.
Our story
It started as an internal spreadsheet in a fabrication shop: the one everybody copied, nobody maintained, and which quietly disagreed with itself about the density of 316 stainless. Two people would work out the same plate and get two answers, and there was no way to see which cell had gone wrong.
The tools available online were not much better. Most returned a single number with no formula, no units shown and no indication of which density had been used. A few were wrong in ways that were hard to spot, because nothing was visible except the result.
So this was built the other way round. The dimensions you type redraw a plate. The formula line shows the numbers actually substituted into it. The density sits next to the grade that carries it. If the answer looks wrong, you can see why in a second rather than rebuilding the calculation somewhere else to check.
Who turns up
Who uses the calculator
Plate weight is one calculation with several very different reasons behind it, and the reason changes what the number has to survive.
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Estimators and quantity surveyors
Weight is the invoice. A price per tonne is only as good as the tonnage it multiplies, and most of that arithmetic happens under time pressure with a drawing in the other hand.
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Fabrication shops
Cutting lists, nesting drops and the gap between what you buy and what walks out as a part. The shapes on the tool are the shapes that come off a profile cutter.
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Stockholders and buyers
Checking a supplier's figure before a purchase order goes out, and knowing which grade the density belongs to when a quote covers several.
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Transport and lifting planners
Load counts and rated capacity. A calculated mass is an input to that work, never the sign-off, and the interface says so rather than implying otherwise.
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Students and apprentices
Volume times density is a short idea that gets long the moment units are mixed. Watching the drawing redraw as a dimension changes does more than another worked example on a page.
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Readers in 18 languages
The calculator, the reference tables and the full home page guide are translated. A plate weighs the same everywhere; the words around it should not be the obstacle.
The principles we build to
A weight estimate has one job: to be defensible when somebody questions it. Each of these is a thing we will not do as much as a thing we do.
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Every figure has a source
No density on this site was invented or averaged into existence. Where published references disagree inside a grade family, we use the widely quoted nominal value and name the disagreement instead of hiding it.
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We say what a number is not
The tool returns theoretical mass from nominal dimensions. It is not a delivered weight, and it is not evidence that a plate is strong enough for anything. Rolling tolerance, mill scale and kerf are called out rather than buried in a disclaimer.
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Nothing you type leaves the browser
There is no account to create and no server a calculation is sent to, so there is nothing for us to store, leak or hand over. That was a constraint accepted early rather than a feature added late: it rules out saved projects and history that follows you between devices, and it is the right trade for a tool people open next to commercially sensitive drawings.
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Free, and funded in the open
The site is free and paid for by advertising. There is no upsell, no gated result and no email wall, and we do not sell what you enter, because we never receive it in the first place.
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Corrections get made
If a density, a conversion or a worked example is wrong, we would rather know. Send the standard reference along with it and the fix goes in, along with a note of what changed.
Where the density figures come from
The calculator carries 37 densities. None of them are invented; each maps to a published standard or a standard reference work.
- ASTM A6/A6M
- General requirements for rolled structural steel bars, plates, shapes and sheet piling
- EN 10029
- Hot-rolled steel plates 3 mm thick or above: tolerances on dimensions and shape
- EN 10025-2
- Technical delivery conditions for non-alloy structural steels
- ASM Metals Handbook
- Reference densities for non-ferrous alloys and engineering plastics
Why a calculated weight and a delivered weight differ
Plate is rolled to a thickness tolerance, and both ASTM A6/A6M and EN 10029 permit a band that is asymmetric about nominal. A nominally 10 mm plate can therefore be delivered slightly over thickness across most of its area, and a full load can weigh a percent or two more than the arithmetic says. Mill scale adds a little again.
That is not an error in the calculation. It is the difference between nominal geometry and rolled steel, and it is why contractual weights are settled against the mill certificate rather than against any calculator, this one included.
What we are working on next
The work queue is shaped by what people write in about. Ahead of everything else: more shape geometries so hexagonal and irregular blanks stop needing a face area worked out by hand, saved cutting lists so a job can be priced in one pass rather than part by part, and coating mass handled inside the tool instead of alongside it.
Further out, the written guides are moving toward the awkward cases rather than the easy ones, because those are where a calculation quietly goes wrong. If something you need is missing, that is the fastest way to get it built.
Get in touch
Found a density we have wrong?
Corrections are genuinely welcome, particularly with a standard reference attached. Write to hello@steelplateweightcalculator.com or use the contact form and we will check it against the source.
Contact UsReferences
Further reading
Pages on this site that go further, and the outside sources checked while writing them.
On this site
Outside references
Work Out Your Plate Weight
Enter length, width and thickness, pick the grade, and read the total. Discs, rings and triangles too, in millimetres or inches.