Daily Survival: Milling Your Own Lumber: How to Tell What a Log Will Give You Before You Cut It

Sunday, October 18, 2026

Milling Your Own Lumber: How to Tell What a Log Will Give You Before You Cut It

Sooner or later, every homestead ends up with logs. A storm drops an oak across the fence line, you clear a patch for the garden, or a neighbor offers you a trailer load of pine for free. With a chainsaw mill or a small band sawmill, those logs can become fence boards, shed framing, shelving and firewood-shed siding instead of a burn pile. But before you start cutting, it pays to know roughly how much usable lumber is sitting in front of you.

Why it is worth estimating first

Milling is hard work and uses fuel, blades and time. An estimate tells you whether a log is worth hauling to the mill at all, how many logs you need for a project, and whether a buyer’s offer for your timber is fair. Professionals do this with a log scale — a rule that converts a log’s diameter and length into board feet.

A board foot is a piece of wood 1 inch thick, 12 inches wide and 12 inches long. A single 2×4 that is 8 feet long holds about 5⅓ board feet, so a 100-board-foot log is roughly nineteen 2×4s’ worth of wood.

How to measure a log

You only need two numbers:

Diameter at the small end, inside the bark. Measure across the narrowest part of the small end; if it is oval, average two measurements at right angles.
Length in feet, usually trimmed to an even length such as 8, 10, 12 or 16 feet.

The small end matters because every board you saw has to fit inside it. The extra wood at the fat end mostly turns into slabs.

The three log rules

There are three rules you will run into, and they give noticeably different answers:

Doyle — the oldest and simplest: ((diameter − 4) ÷ 4)² × length. It badly underestimates small logs and is still common in log buying in the eastern and southern US, which is why sellers of small logs often feel short-changed.
Scribner — based on drawing boards inside circles; used widely in the West. Sits between the other two for most sizes.
International ¼-inch — the most accurate for small and medium logs, because it allows for saw kerf and taper. If you mill your own wood, this is the closest to what you will actually get.

Some real numbers

For a 16-foot log:

12-inch log: Doyle 64 bf, International about 95 bf
16-inch log: Doyle 144 bf, International about 180 bf
20-inch log: Doyle 256 bf, International about 290 bf

Notice the gap on small logs: a 12-inch log is worth a third more lumber than Doyle claims. That gap is called overrun, and it is good news for anyone milling their own timber.

Skip the math in the field

You can do these sums with a pencil, but a phone is quicker when you are standing in the woodlot. A free calculator showing how many board feet in a log puts all three rules side by side for any diameter and length, and it includes a printable log scale chart you can keep in the truck or the shop.

Practical tips for homestead milling

Mill straight, sound logs first. Crooked or rotten logs waste more than the scale suggests.
Cut to the length you need, plus a few inches for trimming.
Stack and sticker immediately. Boards need airflow to dry flat; a rough rule is a year of air-drying per inch of thickness.
Keep the slabs. They make good kindling, rustic siding or raised-bed edges.

Conclusion

A log is not just firewood waiting to happen. Measure the small end, note the length, and run it through a log scale before you decide its fate. You may find that the storm-felled tree behind the barn holds enough lumber for the next shed.

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