Steel Coil Weight Calculator
Calculate coil weight and PIW from dimensional measurements
How It Works
Uses the standard steel density constant of 0.2833 lb/in³.
Formula: Weight = π × ((OD/2)² − (ID/2)²) × Width × 0.2833
PIW: PIW = Weight ÷ Width
Results are rounded to the nearest whole number. Actual weights may vary by steel grade, coating, and tolerances.
Pricing & NPW Calculator
Calculate net package weight and convert between pricing units
NPW Formula
NPW = (Width × Length × Base Weight × 112) / 31,360
A base box = 112 sheets of 14″ × 20″ (31,360 sq in). Sheet weight = NPW / 112.
Thickness Conversion
Convert between base weight, decimal thickness, and metric
Reference Table
| BW (lbs) | Inches | mm |
|---|
Temper Designations
Temper designations and Rockwell hardness values
The term temper summarizes a combination of interrelated mechanical properties. The Rockwell 30T hardness value serves as a guide to the properties of the plate.
Annealing & Reduction
Box annealing — coils are annealed as a batch in a furnace.
Continuous annealing — the strip is annealed in-line as it runs, producing more uniform mechanical properties.
Temper designations do not depend on the annealing method — single reduced is single reduced however it was annealed — and many mills now continuously anneal all production.
Double reduced (DR) — given a second cold reduction after annealing for increased strength and stiffness. DR products are characterized by ultimate tensile strength (UTS) in addition to Rockwell hardness.
Tin Coating Weights
Tin coating weight designations — equal and differential
| Designation | lbs/Base Box | g/m² |
|---|
Differential Coatings
Differentially coated tinplate carries a different tin coating weight on each side — a 50/25, for example, has twice the coating on one surface, typically the side that needs greater corrosion protection.
Because the two sides must be distinguishable, differentially coated tinplate carries one of two marking systems — never both:
How suppliers call it out: conventions vary. Many designations carry a letter — 50 L/25 (line markings) or 50/25 G (geometric markings) — identifying the marking system and therefore the marked side. Others rely on order alone, listing the marked side first: 50/25 indicates markings on the heavier side, 25/50 on the lighter side. When in doubt, confirm the convention with your supplier — or ask us.
Note: surface finish is independent of coating weight. Whether coating levels are equal or differential, both sides of the tinplate share the same finish (matte or bright) — never one finish on one side and another on the other.
Decimal Equivalents
Fraction, decimal (inches), and millimeter conversions
Common Fractions Reference
| Fraction | Decimal (inches) | Millimeters |
|---|
Unit Converter
Common conversions for the steel and tinplate industry
Quick Reference — All Conversion Factors
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RSI Tools
Version 1.4.0
Steel and tinplate industry calculators built by Reynolds Services, Inc. for customers, partners, and industry professionals.
Includes coil weight estimation, pricing and NPW conversions, thickness reference data, temper designations, tin coating weights, decimal equivalents, and unit converters.
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