Density of steel and stainless steel, with a weight calculator

Why is the density almost the same across steel grades?

Steel grades differ in typical density by only 5.4%, from Nitronic 60 stainless steel (UNS S21800) at 7.62 g/cm³ to AISI 309 stainless steel (UNS S30900) at 8.03 g/cm³ across 54 grades, because steel is mostly iron and the other elements are added in smaller amounts. Stainless steel 316 (UNS S31600, EN 1.4401) has a typical density only 1.9% above the carbon-steel median, despite 16 to 18 percent chromium and 10 to 14 percent nickel per its profile.

In this data austenitic stainless steel is the densest stainless family, and carbon and alloy steels sit below it. Duplex stainless steels sit close to carbon steel. Ferritic stainless steel is lighter than every carbon and alloy steel, and most martensitic stainless steels are lighter too. The reason for the order is not in our data; general engineering knowledge, not in our data, points to the nickel in austenitic grades and the different atomic arrangement of each family. Nitronic 60 stainless steel (UNS S21800) is the exception inside the austenitic family: at 7.62 g/cm³ it has the lowest typical density of the 54 grades.

What is the density of each steel and stainless steel grade?

The table gives the density of 54 grades in g/cm³, kg/m³, lb/in³ and lb/ft³ at room temperature. Each value is the median of that grade's sourced records (98 records in all), with a printed range counted as its midpoint. The list of every record, with its printed unit, conversion and source, follows the table.

Grades with no sourced density are listed under what data is missing.

What does steel density mean in practice?

Switching a 10 mm plate from ASTM A36 structural carbon steel to Stainless steel 316L adds 2.9% mass, or 2.3 kg per square metre, at the typical densities in this data. The grade changes mass far less than it changes strength, corrosion resistance or price. For freight or lifting, the supplier's own weight table for the exact grade and product form is the better figure.

How much does a plate or bar weigh?

Plate weight in kilograms per square metre equals the density in g/cm³ times the thickness in millimetres, because one square metre of plate 1 mm thick has a volume of 1,000 cm³. At 7.80 g/cm³, a 10 mm plate of ASTM A36 structural carbon steel weighs 78.0 kg per square metre. The table gives worked examples at each grade's typical density.

Computed from each grade's median density: kg/m² = g/cm³ × 10 for 10 mm; lb/ft² for 1 in plate = lb/in³ × 144; round bar kg/m = g/cm³ × π/4 × 400 × 1,000 / 1,000,000; square bar kg/m = g/cm³ × 400 × 1,000 / 1,000,000.

Why do two tables give different weights for the same grade?

Sources differ in what they print. For Stainless steel 310S (UNS S31008, EN 1.4845) the records hold 7.8 g/cm³ per Aperam Stainless Europe and 8.03 g/cm³ per Goodfellow, AISI 310S Stainless Steel, 2.9% apart. 12 of the 28 grades with two or more single values differ by 1% or more between sources. Some of that is rounding: the datasheet for Stainless steel 316 prints 0.29 lb/in³ next to 8.027 g/cm³, so the lb/in³ figure is itself rounded. Some is composition and heat treatment: 17-4 PH stainless steel is printed at 7.75 g/cm³ in condition A (annealed) and 7.86 g/cm³ in H1150, per Jacquet Metal Service.

Why will a weighed part differ from the calculator?

The calculator gives theoretical weight: the exact shape at a typical density. General engineering knowledge, not in our data, says real parts differ through rolling and cutting tolerances, mill scale, coatings, holes, rounded corners and weld metal. Measuring the actual thickness of the plate or the diameter of the bar removes the largest of these errors.

Does hot steel weigh less?

Hot steel has the same mass but a lower density, because the metal expands. AISI D2 cold-work tool steel (EN 1.2379, X153CrMoV12) (UNS T30402) drops from 7.7 g/cm³ at 20 °C to 7.6 g/cm³ at 400 °C, 1.3% lower, per Uddeholm Sverker 21 (AISI D2); AISI H13 hot-work tool steel (EN 1.2344, X40CrMoV5-1) drops from 7.8 g/cm³ at 20 °C to 7.6 g/cm³ at 600 °C, 2.6% lower, per Uddeholm Orvar Supreme (ESR superior AISI H13). These are the only elevated-temperature densities in our records, so the calculator uses room-temperature values only.

How does steel compare with aluminium and cast iron?

Carbon and alloy steel is about 2.9 times as dense as aluminium 6061, which has a density of 2.7 g/cm³ in T6 and T651 tempers per the ASM data sheet. Gray cast iron (EN-GJL-250) has a single sourced density of 7.2 g/cm³ at 20 °C, lower than every steel in the table. Direct comparisons: steel vs aluminium, iron vs steel, stainless steel vs carbon steel.

What data is missing?

Carbon steel 1045 has a density that was not found in any source we hold, 22 of the 54 grades rest on a single value, and 57 of 98 records do not state the product form. Nothing below was filled in from memory or from another grade.

• 1045 carbon steel: density not found in any source we hold. The profile has no density record, so the grade is not in the calculator, and another grade's number is not borrowed for it. The 1045 carbon steel profile lists the properties we do have.
• 22 of the 54 grades rest on a single value (A36 structural steel, 4130 alloy steel, 4140 alloy steel, 4340 alloy steel, 1.2316 mould steel, Silver steel (BS 1407 high-carbon bright tool steel), 1.2738 mould steel, H13 tool steel and more). For these the typical value is that one number, with no second source to check it.
• Wide printed ranges. 9 records print a range wider than 0.15 g/cm³, for example 1215 free-machining steel, 1070 carbon steel, 4340 alloy steel, 1018 carbon steel, D2 tool steel. A range that wide covers several variants of the grade, so its midpoint is a rough figure; the calculator flags it when it is the only value.
• Form and condition are often missing. 57 of 98 records do not say whether the figure is for plate, bar, sheet or tube, or for which heat treatment. 4 records are printed only in lb/in³ (300M ultra-high-strength steel (UNS K44220), 440C stainless, 420 stainless, 416 stainless), so they were converted and carry the rounding of the original.
• No record says how the value was obtained. Most are typical values from data sheets and product pages; measured and calculated values cannot be told apart. One record (AISI D2 cold-work tool steel (EN 1.2379, X153CrMoV12)) is a relative density printed with no unit, which is treated here as g/cm³.
• Elevated temperature. Only 2 grades have a density above room temperature (D2 tool steel, H13 tool steel), and the calculator ignores them.
• Grades with no profile yet. 1020 steel, 8620 steel, 201 stainless steel, 202 stainless steel, 405 stainless steel are not in the database, so they are not in the calculator. Cast irons, nickel-iron alloys such as Invar and FeCrAl heating alloys are also left out because they are not steels.

What do people ask about the density of steel?

Where can I read more about steel properties?

These pages cover steel and stainless steel selection, tool steels, comparisons of metals and head-to-head grade comparisons. They draw on the same grade profiles as the densities above, so each grade keeps one name and one set of sources across the site.