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Bar length and real log cuts calculator
Updated
Cut counts on listings come from small lumber. This calculator converts them to the wood you have. It also gives the bar length to shop for, using the bar-minus-2 rule of thumb.
Bar length and real log cuts calculator
An estimate for planning, not a measurement. It treats every maker's cut count as if it were counted on a dry 4x4 post, which only EGO confirms. Knots, wet wood, a dull chain and how hard you push all change the real number. The hardwood factor of 1.5 is our assumption.
How the math works
- The 4x4. EGO says its saw makes up to 130 cuts on a 4x4. A nominal 4 inch lumber face is dressed to 3-1/2 inches when dry, so a 4x4 post is 3.5 by 3.5 inches. That is 12.25 square inches of wood per cut.
- Your log. A round log's cross-section is 3.1416 divided by 4, times the diameter squared. A 4 inch limb is 12.6 square inches, about the same as the post. An 8 inch log is 50.3, which is 4.1 posts. A 10 inch log is 78.5, which is 6.4 posts. Work goes up with the square of the diameter, so double the log is four times the cut.
- Hardwood. We multiply by 1.5 for hardwood. That is our assumption, not a maker figure. Dense, dry oak may be worse.
- Cuts per charge. The maker's cut count divided by that number, rounded down. We never show more than the claim itself.
- Bar. Wood size plus 2 inches, rounded up to a common bar size. BLACK+DECKER's page gives its 10 inch saw an 8 inch cut capacity, which is the same rule.
Three worked examples
| Job | Bar to look for | 4x4 cuts per log cut | EGO CS1613 (130) | Greenworks 40V 16 in (120) | DEWALT DCCS621P1 (100) |
|---|---|---|---|---|---|
| 4 in softwood limbs, 30 cuts | 6 in | 1.0 | About 126 per charge, 1 charge | About 116 per charge, 1 charge | About 97 per charge, 1 charge |
| 8 in softwood logs, 20 cuts | 10 in | 4.1 | About 31 per charge, 1 charge | About 29 per charge, 1 charge | About 24 per charge, 1 charge |
| 10 in hardwood logs, 20 cuts | 12 in | 9.6 | About 13 per charge, 2 charges | About 12 per charge, 2 charges | About 10 per charge, 2 charges |
Look at the last row. Twenty cuts of 10 inch hardwood is a modest pile of firewood. By this estimate it takes two charges with any of the three. None of the listings would lead you to expect that. The saws without a cut count, like the Husqvarna Power Axe 350i, are left out because there is no claim to convert, not because they do worse.
See every pick on the roundup page, and read how makers word the claim.
Before any cut
- Gear. CDC lists a hard hat, safety glasses, hearing protection, heavy work gloves, chainsaw chaps from the waist to the top of the foot, and boots that cover the ankle.
- Height. CDC says to always cut at waist level or below. Canada's workplace safety centre says do not saw above shoulder height. No ladders.
- Bar nose. Kickback starts when the top of the bar tip touches something. Know where the tip is at all times.
- People. CDC says keep others at least 30 feet from anyone cutting limbs or a fallen tree, and at least 150 feet from anyone felling a tree.
- Battery saws are still chainsaws. They are quiet and start with a button. The chain does not care. Take the battery out before you touch the chain.