{"id":5549,"date":"2020-10-06T15:17:48","date_gmt":"2020-10-06T15:17:48","guid":{"rendered":"https:\/\/www.ammunitiontogo.com\/lodge\/?p=5549"},"modified":"2025-10-08T20:04:54","modified_gmt":"2025-10-08T20:04:54","slug":"sectional-density","status":"publish","type":"post","link":"https:\/\/www.ammunitiontogo.com\/lodge\/sectional-density\/","title":{"rendered":"What is Sectional Density?"},"content":{"rendered":"

\u201cSectional Density\u201d (SD) sounds complicated, and it involves more math than most people can do in their head, but it describes a very simple concept. In a single number, SD reflects how deeply a bullet can penetrate.<\/p>\n

What is Sectional Density?<\/h2>\n

\"The<\/p>\n

Sectional density is the mass of a bullet divided by the area that it covers. If two bullets have the same mass but one is physically larger than the other, its sectional density will likely be higher. Sectional density plays a large role in how well a bullet penetrates a target. Sectional density and ballistic coefficient<\/a> are somewhat related. While sectional density relates to targets, ballistic coefficient is related to how well a bullet cuts through the air toward its target.<\/p>\n

The Sectional Density Equation<\/h3>\n

\"The<\/p>\n

A bullet\u2019s sectional density is determined entirely from two factors: weight and diameter.<\/p>\n

You can calculate it with this handy formula:<\/p>\n

SD = (weight in grains) \/ 7000 * (diameter in inches) * (diameter in inches)<\/p>\n

SD shows how well an object\u2019s weight is distributed for it to overcome resistance from the thing that it hits. Think of it like this. You have two cone-shaped lawn darts, which share identical weights. One is three inches long, so it is shaped like an open umbrella. The other is twelve inches long and pointy as a spear tip. You drop both from eye level. Which lawn dart do you think will stick deeper into the ground?<\/p>\n

When you consider bullets of the same caliber, it is only their weights that give them different SD\u2019s. For instance, our most commonly sold 5.56 NATO ammo<\/a> is often available with a 55, 62, or 77 grain bullet. Its SD can therefore be as follows:<\/p>\n

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\n \"product\"\n <\/div>\n
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\n $511.95 <\/div>\n <\/div>\n <\/div>\n
\n \"logo\"\n <\/div>\n <\/div>\n
\n 1000rds \u2013 5.56x45 PMC X-TAC 62gr. FMJ M855 Ammo <\/div>\n <\/div>\n <\/a>\n <\/div>\n
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\n \"product\"\n <\/div>\n
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\n $14.95 <\/div>\n <\/div>\n <\/div>\n
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\n 20rds \u2013 5.56x45 PMC X-TAC 62gr. FMJ M855 Ammo <\/div>\n <\/div>\n <\/a>\n <\/div>\n