As a rough rule, each extra foot of rotavator width needs about 5 to 10 more tractor horsepower. A 4 ft machine often suits 25 to 35 HP, while an 8 ft machine usually needs 55 HP or more.
These are rules of thumb drawn from typical Indian maker charts, not fixed limits. Soil type, working depth and rotor speed can move the real requirement by a wide margin.
Typical ranges by width
The ranges below are indicative for medium soil at normal working depth. Always confirm against the chart of the maker you buy from.
- A 4 ft rotavator, about 1.2 metres wide, usually suits tractors of about 25 to 35 HP.
- A 5 ft rotavator, about 1.5 metres wide, usually suits about 35 to 45 HP.
- A 6 ft rotavator, about 1.8 metres wide, usually suits about 45 to 50 HP.
- A 7 ft rotavator, about 2.1 metres wide, usually suits about 50 to 55 HP.
- An 8 ft rotavator, about 2.4 metres wide, usually needs about 55 HP or more.
What moves the number
Heavy clay, wet soil and stony ground need more power than light, dry soil. Deeper tillage needs more power too. If your farmers work heavy land, move one width down for a given tractor.
Rated tractor horsepower is usually engine power, not PTO power. PTO power is lower after transmission losses, so check which figure the maker's chart uses.
The gearbox and side drive must also match the tractor. A big tractor on a light-duty gearbox can break it, even if the width looks right. Ask the maker for the gearbox's rated input power.
Hitch category matters as well. The rotavator's linkage pins must fit your tractors, as covered in which PTO and three-point linkage standards apply.
How to set your range
Start with the tractors your customers actually own. List the common models, their PTO power and their hitch category. Then pick the widths that cover most of that list.
Put the matching tractor power range on the label and in the manual. It reduces misuse, and with it a large share of gearbox and warranty complaints. For width basics, see what a rotavator is and what widths are available.
Testing the match before you buy
A maker's chart is a starting point. The safer route is a field trial on soil like yours, with the tractor model your customers use most. Watch whether the tractor holds engine speed at working depth, and whether it can lift the machine cleanly at the headland.
If a trial in your market is not possible, ask the maker to run the machine on a similar tractor in India and record the result. A short video with the tractor model, gear, depth and soil noted is far more useful than a claim in a brochure.
Keep the results with your product file. They will help you answer dealer questions and judge later warranty claims fairly.
Next step
We check makers' power charts against tests and samples before you commit. To match a rotavator range to your tractors and soils, book a free sourcing review.