Table of Contents
Rotary cutting is slower and less predictable than finish mowing. Vegetation density, hidden obstacles and slopes all affect the pace. Still, the standard formula gives a solid starting point, and a realistic rotary cutter acres per hour rate will hold up far better than a guess.
A bush hog is a rotary cutter: a wide deck with heavy blades that spin on a vertical shaft, pulled behind a tractor and driven by the tractor power take off. It clears overgrown pasture, field edges and rough ground that a normal mower cannot handle. The cut is coarse and the finish is uneven, which is normal for this job. Read the what is bush hogging guide for the full definition, including what land it suits and how it differs from finish mowing.
Rotary Cutter Acres Per Hour by Cutter Width
Rotary cutter acres per hour equals width in ft times speed in mph times efficiency divided by 8.25. The table below repeats the live rate table at 4 mph, with every figure recalculated and confirmed. Open pasture uses 80 percent efficiency, average ground uses 75 percent, and rough ground uses 65 percent.
| Cutter | Speed | Open pasture, 80 percent | Average, 75 percent | Rough, 65 percent |
|---|---|---|---|---|
| 4 ft | 4 mph | 1.55 | 1.45 | 1.26 |
| 5 ft | 4 mph | 1.94 | 1.82 | 1.58 |
| 6 ft | 4 mph | 2.33 | 2.18 | 1.89 |
| 7 ft | 4 mph | 2.72 | 2.55 | 2.21 |
| 10 ft | 4 mph | 3.88 | 3.64 | 3.15 |
| 15 ft | 4 mph | 5.82 | 5.45 | 4.73 |
| 20 ft | 4 mph | 7.76 | 7.27 | 6.30 |
Read the table across a row to see what growth costs, and down a column to see what width buys. A 6 ft cutter drops from 2.33 rotary cutter acres per hour on open pasture to 1.89 on rough ground, a loss of about 19 percent. A 20 ft cutter covers 7.76 acres per hour on open pasture, more than three times the 6 ft rate, but it needs open ground, wide gates and a tractor with enough power to keep the blades at full speed.
Use the bush hog acres per hour calculator to compare cutter widths and terrain settings for your own job. Use the how to calculate acres per hour guide for the full method, and the Acres Per Hour Calculator for any width and speed.
Choosing the Right Speed
The right speed is the fastest pace at which the blades keep full speed and leave a clean cut. In light pasture regrowth that may be 4 to 5 mph. In thick, tall growth or saplings it can fall to 1 to 2 mph. When the engine labours or the cut looks ragged, slow down.
Speed is the input most operators overstate. Top speed on a clear stretch is not average speed for the day, and a cutter that is pushed too fast in heavy growth will leave uncut strips that need a second pass. A second pass doubles the time for that ground, so the fast pass was not fast at all. Plan from the speed you can hold while the blades stay at full speed and the cut stays clean.
Wet ground forces slower speeds too, because wheels slip and the tractor cannot hold a steady pace. Slopes force slower speeds for safety, and the safe speed on a slope is set by the tractor and the ground, not by the clock. If the job is on a slope, walk it first and decide the speed from the ground, not from the table.
Estimating a Job
A 30 acre overgrown field, a 7 ft cutter, 3 mph in heavy growth and 65 percent efficiency: the rate is 7 times 3 times 0.65 divided by 8.25, which is 1.65 rotary cutter acres per hour when rounded. Time is 30 divided by the unrounded rate, which is 18.1 hours. Walking the field first and marking stumps and holes improves both safety and efficiency, because the operator can plan around hazards instead of discovering them at speed.
Try a smaller job at a faster rate. A 10 acre pasture with a 6 ft cutter at 4 mph and 75 percent efficiency runs at 2.18 rotary cutter acres per hour. Time is 10 divided by 2.18, which is 4.6 hours. On rough ground at 65 percent efficiency, the same cutter runs at 1.89 acres per hour, and the same 10 acres takes 10 divided by 1.89, which is 5.3 hours. Growth alone adds about three quarters of an hour to a small job.
| Acres | At 1.65 acres per hour | At 2.18 acres per hour |
|---|---|---|
| 10 | 6.1 hours | 4.6 hours |
| 20 | 12.1 hours | 9.2 hours |
| 30 | 18.2 hours | 13.8 hours |
| 50 | 30.3 hours | 22.9 hours |
The table is worked from the rounded rates, so small rounding differences apply. Use it to see the pattern: at a slow rate, a 50 acre job is a week of work at 6 productive hours a day, while at a faster rate it is under four days. Turn these hours into working days and calendar days by counting productive hours and workable days.
The homepage example shows the same method at a lighter rate. A 6 ft cutter at 4.5 mph and 75 percent efficiency covers 2.45 acres per hour, so a 20 acre pasture takes 20 divided by 2.45, which is about 8.2 hours of cutting time. That time is cutting time in the field. It does not include travel, fuel stops or time spent clearing debris.
Factors That Slow Rough Cutting
Woody stems thicker than the cutter is rated for slow the work and risk damage. The cutter can chop light saplings and brush within its safe working limits, but it cannot clear large trees or heavy woodland. Stems that are too thick force the operator to slow down, lift the deck or stop and clear the blockage.
Rocks, stumps, old fencing and debris hidden in tall grass are the most common surprise. Each one forces a slowdown or a stop, and a strike can damage blades, the deck or the power take off shaft. Walk the field before you start, mark every hazard you find, and plan passes that avoid them where you can. A walk that takes half an hour can save hours of slow cautious passes.
Slopes slow the work because safe operation requires slower speeds, and wet ground slows it because wheels slip and ruts form. Both also raise the risk of losing control, so the slowdown is not wasted time. It is the price of working safely, and it belongs in the estimate from the start.
Safety Basics
Bush hogging throws debris, so keep people and animals well clear. Never let anyone walk beside the cutter while it is running. Stay in the seat, keep hands and feet clear of moving parts, and wait for the blades to stop before you inspect the cutter.
Check the machine before you start. Check tyres, blades, guards and the power take off shaft, and make sure the deck raises and lowers freely. Check that the cutter can pass through gates and turn inside the field, and plan long straight passes with a small overlap. Work within safe limits for slopes, and wear eye and hearing protection with sturdy boots.
Pricing Rough Cutting
Because conditions vary so much, many contractors price per hour or inspect before quoting per acre. If you quote per acre, base it on a conservative efficiency. A quote built on 80 percent efficiency for rough ground will lose money, because the real rate will be closer to 65 percent and the hours will run long.
Work the price from the rate the way the contractor pricing guide shows: hourly cost divided by rotary cutter acres per hour gives cost per acre, then add travel, setup and margin. As an example from that guide, an hourly cost of 90 dollars divided by the unrounded rate of 2.3758 acres per hour (2.38 when rounded) gives 37.88 dollars per acre before profit, from a 7 ft cutter at 4 mph and 70 percent efficiency. The dollar figures here are an illustration only. Use your own costs.
For bush hog work, the bush hogging cost per acre guide explains how cost per acre is worked out from time, area, cutter width, terrain and your hourly rate. Inspect the ground before you quote per acre, and put the terms in writing so both sides know what the price covers.
Common Mistakes
The most common mistake is to use machine width instead of working width. Measure the actual cut swath minus overlap and use that figure in the formula. Using the wrong width makes the estimate too high and the job takes longer than planned. Overlap is larger on rough ground, because the operator overlaps more to avoid missing strips hidden by tall growth.
The second mistake is to use top speed instead of average speed held safely, and to assume high efficiency for a difficult field. Rough ground, hidden hazards and short passes all push efficiency down, and the table above shows how far: the same cutter can lose a fifth of its rate between open pasture and rough ground.
Frequently Asked Questions
Q: How many acres per hour can a bush hog cut?
A: It depends on width, speed and growth. At 4 mph, rotary cutter acres per hour for a 6 ft cutter is 2.33 on open pasture, 2.18 on average ground and 1.89 on rough ground. A 15 ft cutter covers 5.82, 5.45 and 4.73 at the same speeds and efficiencies.
Q: How long does it take to bush hog 30 acres?
A: With a 7 ft cutter at 3 mph in heavy growth and 65 percent efficiency, the rate is 1.65 acres per hour and 30 acres takes 18.1 hours of cutting time. Travel, fuel stops and clearing debris add time on top.
Q: What speed should I bush hog at?
A: Use the fastest pace at which the blades keep full speed and leave a clean cut. That may be 4 to 5 mph in light regrowth, and 1 to 2 mph in thick tall growth or saplings. Slow down when the engine labours or the cut looks ragged.
Q: Can bush hogging clear saplings and brush?
A: It can clear light saplings and brush within the safe working limits of the cutter. It cannot clear large trees or heavy woodland, and woody stems thicker than the cutter is rated for will slow the work.
Q: How long does it take to bush hog 20 acres?
A: At 2.45 acres per hour, from a 6 ft cutter at 4.5 mph and 75 percent efficiency, cutting time is about 8.2 hours. That is cutting time only, before travel and breaks.
Q: Should I charge per acre or per hour for bush hogging?
A: Price per hour or inspect before quoting per acre, because conditions vary so much. If you quote per acre, base it on a conservative efficiency, such as 65 percent for rough ground, and put the terms in writing.
Rotary cutting rewards the operator who plans for the rough ground in front of them, not the open pasture in the brochure. Use the table rotary cutter acres per hour rate for your width and growth, walk the field, hold a speed the blades can sustain, and the estimate will hold.
