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Electrical Steel Weight CalculatorCoil, sheet, lamination stack and EI core weight, worked out by grade
Weight (kg) = thickness × width × length × density ÷ 106, with dimensions in mm and density in g/cm³. Grain-oriented steel uses 7.65 g/cm³. Non-oriented grades run from 7.60 to 7.85 g/cm³, depending on silicon content. Pick a grade, enter your sizes, and the calculator applies the right density and stacking factor for you.
Free engineering tool
Silicon steel weight & coil length calculator
There are four modes. Coil gives weight from the outer diameter, or length and outer diameter from a target weight. Sheet & strip handles cut lengths. Lamination stack covers rectangular, ring or CAD-area laminations. EI laminations works from standard scrapless EI sizes. The grade, thickness, density and stacking factor are shared by all four tabs.
508 mm (20″) standard · 610 mm on request
Read the area of one lamination (slots and holes removed) from your CAD drawing.
Square stack = stack height equal to a
Theoretical weight is based on nominal thickness and conventional density. Packing lists and invoices show the actual weighed net weight. See theoretical vs. shipped weight ↓
How it’s measured
How the calculation works
Every mode comes down to one thing: steel volume × density. Coil and stack modes also multiply by the stacking factor, because the wound or stacked steel is not 100% solid metal. Dimensions are in mm and density in g/cm³, so dividing by 106 gives kilograms.
| Mode | Formula | Worked example |
|---|---|---|
| Sheet & strip | W = t × width × length × ρ ÷ 106 per piece | 0.27 × 1,000 × 2,000 × 7.65 ÷ 106 = 4.13 kg per sheet |
| Mass per area | kg/m² = t × ρ | 0.27 mm × 7.65 = 2.07 kg/m² · 0.50 mm × 7.70 = 3.85 kg/m² |
| Coil weight from OD | W = π/4 × (OD² − ID²) × width × ρ × SF ÷ 106 | OD 1,000 · ID 508 · 1,000 mm wide · 0.27 mm CRGO → ≈ 4,235 kg |
| Strip length from weight | L (m) = W ÷ (t × width × ρ ÷ 103) | 4,235 kg ÷ 2.0655 kg/m ≈ 2,050 m of 0.27 × 1,000 mm strip |
| Laminations per stack | n = stack height × SF ÷ t | 100 mm × 0.95 ÷ 0.35 mm ≈ 271 laminations |
| Scrapless EI set | E + I area = 6a² (outline 3a × 2.5a) | EI-96, a = 32 mm → 6,144 mm² → 23.7 g per set at 0.50 mm |
t = thickness (mm) · ρ = density (g/cm³) · SF = stacking factor · OD / ID = coil outer / inner diameter (mm). Lb/ft = kg/m × 0.672.
Technical & physical properties
Why the grade changes the weight
Silicon and aluminium lower the density of iron as they raise its resistivity. That makes a low-loss grade lighter than a high-loss grade of the same size. A generic steel chart uses 7.85 g/cm³, which overstates a 7.60 grade by about 3%. On a 25 t order that is roughly 800 kg of steel that isn’t there.
| Family · thickness | Grades | Density (g/cm³) | vs. 7.85 chart |
|---|---|---|---|
| Grain-oriented · 0.23–0.35 mm | All CRGO and Hi-B (M-3 to M-6, 23QG085 to 30QG110) | 7.65 | −2.5% |
| Non-oriented · 0.35 mm | M235-35A, M250-35A | 7.60 | −3.2% |
| Non-oriented · 0.35 mm | M270-35A, M300-35A, M330-35A | 7.65 | −2.5% |
| Non-oriented · 0.50 mm | M250-50A to M290-50A | 7.60 | −3.2% |
| Non-oriented · 0.50 mm | M310-50A to M350-50A | 7.65 | −2.5% |
| Non-oriented · 0.50 mm | M400-50A, M470-50A, M530-50A | 7.70 | −1.9% |
| Non-oriented · 0.50 mm | M600-50A | 7.75 | −1.3% |
| Non-oriented · 0.50 mm | M700-50A, M800-50A | 7.80 | −0.6% |
| Non-oriented · 0.50 mm | M940-50A | 7.85 | 0 |
| Non-oriented · 0.65 mm | M310-65A to M350-65A | 7.60 | −3.2% |
| Non-oriented · 0.65 mm | M400-65A, M470-65A | 7.65 | −2.5% |
| Non-oriented · 0.65 mm | M530-65A | 7.70 | −1.9% |
| Non-oriented · 0.65 mm | M600-65A, M700-65A | 7.75 | −1.3% |
| Non-oriented · 0.65 mm | M800-65A, M1000-65A | 7.80 | −0.6% |
| Thin non-oriented · 0.20–0.30 mm | High-frequency motor grades | 7.60 | −3.2% |
These are conventional densities: the fixed values the grade standards use to convert measured mass into cross-section for core-loss testing (EN 10106 / IEC 60404-8-4 for non-oriented grades, 7.65 g/cm³ for all grain-oriented grades under ASTM A34 and EN 10107). GB grades take the IEC value, so 50W470 = M470-50A at 7.70. Cross-references for every grade are in the grade equivalents chart →
Choosing a grade
Stacking factor: why 100 mm of stack isn’t 100 mm of steel
Insulation coating, surface roughness and flatness leave thin gaps between laminations. The stacking factor is the solid-steel share of a stack. Thinner gauges have more interfaces per millimetre, so their stacking factor is lower. The calculator applies the minimums below by default. If your own stacking test shows a different figure, overwrite it.
| Thickness | Grain-oriented (min.) | Non-oriented (min.) |
|---|---|---|
| 0.20 mm | — | 0.93 (thin NGO) |
| 0.23 mm | 0.945 | — |
| 0.25–0.27 mm | 0.950 (0.27 mm) | 0.94 (thin NGO) |
| 0.30 mm | 0.955 | 0.95 (thin NGO) |
| 0.35 mm | 0.960 | 0.95 |
| 0.50 mm | — | 0.96 |
| 0.65 mm | — | 0.97 |
Grain-oriented values follow EN 10107 grade minimums; non-oriented values follow EN 10106 and published mill data for thin high-frequency grades. How it is measured and what lowers it: lamination stacking factor explained →
Worked examples
Three questions buyers send us
01
“How long is a 1,000 mm OD coil?”
0.27 mm CRGO, 1,000 mm wide on a 508 mm ID: about 4.2 t and 2,050 m of strip at 2.07 kg/m.
02
“How much steel for 1,000 EI-96 cores?”
M470-50A, 32 mm square stack: 61 sets and about 1.44 kg per core, so roughly 1.44 t for the batch.
03
“What does a stator stack weigh?”
M270-35A ring, 200/120 mm, 100 mm stack: 271 laminations and about 14.6 kg before slots are punched.
Side by side
Theoretical weight vs. shipped weight
The calculator gives a theoretical net weight from nominal sizes. Use it for planning and quotations. Use the weighed figures on the packing list for anything that has to reconcile.
| Purpose | Weight to use | Why |
|---|---|---|
| Budget, RFQ, core design | Theoretical net (this calculator) | Based on nominal thickness and conventional density, so every supplier quotes on the same basis |
| Invoice and payment | Actual net weight per coil or bundle | Each coil is weighed after slitting or cutting and listed on the packing list and mill certificate |
| Freight, crane, customs | Gross weight | Adds pallets, steel bands, edge protection and VCI wrap, which you should ask for with the quote |
| Reconciling a delivery | Actual net vs. theoretical | Thickness tolerance is the main cause of difference: ±0.030 mm on 0.27 mm is ±11% at the limits, though coil averages run much closer to nominal |
FAQ
Frequently asked questions
How do I calculate the weight of a silicon steel coil?
Multiply the ring area by the width, density and stacking factor: W (kg) = π/4 × (OD² − ID²) × width × ρ × SF ÷ 106, with dimensions in mm and density in g/cm³. A 0.27 mm CRGO coil 1,000 mm wide, with a 1,000 mm OD on a 508 mm ID, weighs about 4,235 kg. If you know the weight but not the OD, choose “Coil weight → length & OD” in the calculator.
What density should I use for electrical steel?
Use 7.65 g/cm³ for all grain-oriented grades. For non-oriented grades, use the value for the grade: from 7.60 g/cm³ for low-loss, high-silicon grades such as M250-50A up to 7.85 g/cm³ for M940-50A. The general steel figure of 7.85 overstates most electrical steel by 2–3%.
How do I convert coil weight into strip length?
Divide the weight by the mass per metre: L (m) = W ÷ (t × width × ρ ÷ 1,000). For 0.27 × 1,000 mm grain-oriented strip, one metre weighs 2.0655 kg, so a 5 t coil holds about 2,420 m. Stacking factor does not enter the length calculation, because it only describes the gaps between wraps.
Why does the calculator use a stacking factor?
A stack or a wound coil is not solid steel: coating and surface roughness leave small gaps between layers. The stacking factor (0.93–0.97 depending on thickness) converts the outside dimensions of a stack or coil into the actual mass of steel. It is applied to coil-from-OD, lamination stack and EI results, but not to sheet weight or strip length. More detail is in our stacking factor guide.
How many laminations are in a core stack?
Divide the stack height by the thickness and multiply by the stacking factor: n = height × SF ÷ t. A 100 mm stack of 0.35 mm M270-35A at 0.95 holds about 271 laminations. Thinner gauges need more laminations for the same height. See the electrical steel thickness guide for how gauge affects core loss.
Is the calculated weight the same as the invoiced weight?
Not exactly. The calculator gives theoretical net weight from nominal sizes. Invoices and packing lists use the actual weighed net weight of each coil or bundle, which can differ by a few percent within thickness tolerance. Freight and lifting plans need the gross weight, including packaging.
What is the minimum order for electrical steel coil or sheet?
Coil orders typically start at about 5 t, and sheet from 500 kg. Both usually ship in about 15 days. If you need less than a full coil, we slit or cut it from a master coil. Tell us the quantity and we will do our best to meet it.
Can I use it for ultra-thin grades?
Yes. Thin non-oriented grades from 0.20 to 0.30 mm are in the grade list. For grain-oriented strip from 0.05 to 0.20 mm, choose “Custom”, enter 7.65 g/cm³, and use the stacking factor from the material datasheet. At these gauges the coating is a larger share of the thickness, so the factor is lower than for 0.23 mm and above. Our ultra-thin silicon steel range covers these gauges.
Related resources
Next steps after the numbers
Grade equivalents
Match GB, IEC/EN, JIS and AISI grade names before you order.
Open chart →Stacking factor explained
How it is measured, and what coating and burrs do to it.
Read →CRGO steel coil
Grain-oriented coil and slit strip for transformer cores.
View CRGO →CRNGO steel coil
Non-oriented coil for motor and generator laminations.
View CRNGO →Need a price on this size?
Send the grade, thickness, width and quantity from the calculator. We reply with pricing and availability within 24 h.
