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Kelly Calculator

We have developed this Productivity Calculator to help you understand the costs and benefits you might expect from a Kelly Diamond Harrow. By using information from your own farm, you can see the productivity of the selected tools, including recommended horsepower, running costs and expected wear rate. We hope you find this informative.

Please enter your name and email to use the form to calculate the results

All fields require user input. Some fields, such as productive efficiency and fuel usage, contain default or assumed values. These default values may be overwritten.

Tractor kW:
Kelly Model:
Chain/Disc type:
Soil type:
Speed of operation (km/h):
Labour cost ($/hr):
Productive efficiency (%):
Fuel price ($/litre):
Fuel consumption litres per hour, leave default or enter your own figure

*Default Litres/hour calculated from your tractor kW using the formula 3.7kW/hr/litre

Currency Adjustment:
Custom Exchange Rate:

Crop type
Crop Hectares sown
Pre Planting passes
Average yield in Kg / Ha
Commodity price per MT (in $)

Planter width in Metres
Average start of planting date
Normal planter operating speed km/h
Average start of harvest date

*Expect at least 1.6 km/h planting speed increase

Expected number of days you can enter
the field earlier than usual by using Kelly
Expected increase in planter speed
Glyphosate cost per litre (in $)

*Expect at least 1.6 km/h planting speed increase

Glyphosate application rate litres per ha.
Expected % improvement in plant
establishment using Kelly
Per ha application cost of herbicide
application (per ha.)

Expected weed kill % from herbicide

The information that you provide will be used by Kelly Tillage to contact you with relevant information about our business, products, and services. We will hold this information for as long as necessary, and may pass it on to our dealers and associates in the interests of providing you with personalised customer service. Your information is your property, and you retain the right to request access, transferral, rectification, and erasure of it, as well as the right to withdraw consent to our use of it and the right to lodge a complaint with a Data Protection Authority (DPA).

  Terms and Conditions:

This calculator is intended to stimulate questions and thinking about the uses of the Kelly Tillage System. Although we have taken great care in researching the formulae and factors used in this calculator, it is to be used for illustrative purposes only. Our assumptions are transparent and supported by many years of field experience. In all instances throughout the calculator you may override our assumptions and use your own. Kelly cannot accept any liability for the use of this information or for the outcome of any decision you make as a result of this calculator.



Planter productivity: Ha per hour
Increase in Planter productivity: Ha per hour
Improved planter productivity result: Ha per hour
Planting hours saved: Hours
Growing season -Days between planting and harvest: Days
Percentage increase in growing season by accessing fields sooner
Percentage increase in production through stand/germination and establishment improvement

Tool Wear

Tool Type:
Total Ha worked each year:
Expected life of the tool in Ha:
Number of years in your program before tool replacement:
Price of a replacement set of tools:
Cost of tool wear per annum:


Glyphosate cost per Ha - applied:
Cost of one spray pass over full crop area:
Cost of Kelly for one full pass:
Benefit of one weed kill substitution:
Yield Data
Calculated increase in growing season: (Assumption : 1% increase in growing season = 1% increase in production)
Stand increase: (Assumption : 1% increase in stand establishment = 0.5% increase in production.)
Crop1 Crop2 Crop3 Crop4
Standard yield kg/ha
Revised yield kg/ha
Value of increased yield per ha
Value of increased yield per ha
Sum of improvement in income

Selected Model Specifications

kW Recommended: kW
Productivity for the Kelly: Ha per hour
Fuel cost: per Ha
Labour cost: per Ha
Working cost of Kelly including labour, fuel and wear: per Ha
Farm size: Ha
Area worked with the Kelly each year: Ha
Total machinery cost per year (Cost per Ha * Ha worked):


Which model can I pull with my tractor?

Your existing Tractor: kW
Based upon your tractor, soil type and disc selection you could manage a model: with an effective width of m.
To stay ahead of your planter you will need a model: