Cost Per Hour & Own or Custom-Hire
Costs out your tractor
What does each hour and acre of running your tractor or combine truly cost — the fixed DIRTI-5 (depreciation, interest, repairs, taxes, insurance) plus variable fuel, lube and labour — and should you custom-hire instead? Built on ASABE EP496/D497 RF1/RF2 repair factors and fuel-per-PTO-hp for a number you can defend.
Enter your machine
More hours spreads the fixed cost — watch the fixed layers shrink.
Next: at 4 ac/hr owning beats the custom rate — keep the machine busy past 300 ac/yr and you are ahead. If repairs dominate the stack, budget a rebuild fund rather than trading early.
Fixed = depreciation + interest + taxes/insurance/housing + ASABE repairs; variable = fuel + lube + labour. Repairs use AccRepairs = price × RF1 × (h/1000)^RF2 (ASABE D497).
Machinery cost — key facts
- DIRTI-5
- Depreciation, Interest, Repairs, Taxes, Insurance
- Depreciation
- (price − salvage) ÷ ownership years
- Interest & THI base
- average investment = (price + salvage) ÷ 2
- Repairs (ASABE)
- price × RF1 × (h ÷ 1000)^RF2
- Diesel use
- ≈ 0.227 L per rated-PTO-hp·h (D497)
- Lube
- ≈ 15% of fuel cost
- Break-even acres
- fixed/yr ÷ (custom rate − own variable/acre)
- Privacy
- Runs in your browser; nothing uploaded
ASABE repair factors & useful life by machine class
From ASABE Standard D497 (Agricultural Machinery Management Data). Accumulated repairs over the machine's life = list price × RF1 × (hours ÷ 1000)RF2; dividing by the useful-life hours gives the repair cost per hour the calculator uses.
| Machine class | RF1 | RF2 | Useful life (h) | Fuel basis |
|---|---|---|---|---|
| Tractor, 2WD | 0.007 | 2 | 12,000 | Engine PTO power |
| Tractor, 4WD / MFWD | 0.003 | 2 | 16,000 | Engine PTO power |
| Combine (self-propelled) | 0.04 | 2.1 | 3,000 | Engine PTO power |
| Self-propelled windrower | 0.04 | 2.1 | 3,000 | Engine PTO power |
| Self-propelled forage harvester | 0.03 | 2 | 4,000 | Engine PTO power |
| Moldboard plow | 0.34 | 1.8 | 2,000 | Tractor pulling it |
| Chisel plow / disk-ripper | 0.28 | 1.8 | 2,000 | Tractor pulling it |
| Tandem disk harrow | 0.18 | 1.7 | 2,000 | Tractor pulling it |
| Field cultivator | 0.27 | 1.4 | 2,000 | Tractor pulling it |
| Rotary tiller / rotavator | 0.36 | 2 | 1,500 | Tractor pulling it |
| Row-crop planter | 0.32 | 2.1 | 1,500 | Tractor pulling it |
| Grain drill / seed drill | 0.32 | 2.1 | 1,500 | Tractor pulling it |
| Self-propelled / mounted sprayer | 0.41 | 1.3 | 2,000 | Tractor pulling it |
| Fertilizer spreader | 0.63 | 1.3 | 1,200 | Tractor pulling it |
| Mower-conditioner | 0.18 | 1.6 | 2,500 | Tractor pulling it |
| Rake / tedder | 0.17 | 1.4 | 2,500 | Tractor pulling it |
| Round baler | 0.43 | 1.8 | 1,500 | Tractor pulling it |
| Square baler | 0.23 | 1.4 | 2,500 | Tractor pulling it |
Fixed cost is the trap — utilisation is the lever
Most farmers underestimate machinery cost because they only count diesel. The real cost is dominated by the fixed DIRTI-5 burden — depreciation, interest, repairs, taxes and insurance — that you carry whether the machine moves or not. A combine sitting in a shed still loses value, still ties up capital, and still needs insurance. Spread that fixed pile over too few hours and the cost per hour balloons; spread it over more acres and it falls. That is the single biggest decision in machinery economics, and it is exactly what the use-hours slider in this tool makes visible.
The repairs layer is where rough calculators go wrong. Repairs do not stay flat at 5% of price — they accelerate as a machine ages, which is why ASABE fits the power law AccRepairs = price × RF1 × (hours ÷ 1000)RF2 with class-specific factors. A combine's RF2 of 2.1 means its repair cost grows steeply; a 4WD tractor's low RF1 of 0.003 means it stays cheap to maintain for thousands of hours. Pair this number with the custom-hire break-even, and you can answer the real question: own it, or pay someone per acre?
Defensible per-hour cost
ASABE RF1/RF2 repairs and fuel-per-hp, not a flat percentage.
See the fixed-cost trap
Drag use-hours and watch the fixed layers shrink per hour.
Own vs custom-hire
The break-even acreage where owning starts to win.
Per-acre too
Convert the hourly cost to cost per acre at your work rate.
Frequently Asked Questions
What is the DIRTI-5 method for machinery cost?+
DIRTI is the classic ownership-cost acronym: Depreciation, Interest, Repairs, Taxes and Insurance. These are the fixed costs you carry whether the machine works one hour or a thousand. This calculator adds the variable costs — fuel, lubrication and labour — on top, so the per-hour figure is the full economic cost, not just running expenses. Depreciation is spread straight-line over your ownership years; interest and taxes-insurance-housing are charged on the average investment.
How are repairs calculated — why ASABE RF1 and RF2?+
Repairs do not rise linearly with age; they accelerate. ASABE Standard D497 fits an accumulated-repair power law: accumulated repairs = list price × RF1 × (hours ÷ 1000)^RF2, where RF1 and RF2 are published per machine class. A combine (RF1 0.04, RF2 2.1) accumulates repairs far faster than a 4WD tractor (RF1 0.003, RF2 2.0). Dividing the lifetime accumulated repairs by the machine's useful-life hours gives a defensible repair cost per hour — far better than a flat 5% guess.
How is the fuel cost per hour worked out?+
Fuel use is driven by power, not by the machine's price. ASABE D497 gives average diesel consumption of about 0.305 litres per kilowatt-hour of PTO power, which converts to roughly 0.227 litres per rated-PTO-horsepower-hour. The tool multiplies rated PTO horsepower × the field load fraction × that rate × your diesel price. Lubrication is added at about 15% of fuel cost, per ASABE convention.
Why does the cost per hour fall as I increase use hours per year?+
Fixed costs (depreciation, interest, taxes, insurance) are annual amounts that do not change with how much you use the machine. Spreading the same fixed pile over more hours means each hour carries less. That is why a combine used 150 hours a year can cost two to three times as much per hour as the same combine used 400 hours — the utilisation slider in the tool shows the fixed layers shrinking live as you drag it up.
Should I own this machine or custom-hire it?+
It depends on acreage. Owning carries the fixed cost regardless of use; custom hiring is a flat rate per acre with no fixed cost. The break-even acreage is fixed-cost-per-year ÷ (custom rate per acre − your own variable-plus-repairs cost per acre). Below that acreage, hiring is cheaper; above it, owning wins. The calculator computes this crossover for your numbers and flags whether you are above or below it.
What is interest on the average investment?+
Even if you paid cash, the money tied up in the machine could have earned a return — that opportunity cost is real. ASABE charges interest on the average investment, taken as (purchase price + salvage value) ÷ 2, because the capital tied up declines over the machine's life. At 8% interest a $300,000 combine with $60,000 salvage carries 0.08 × $180,000 = $14,400 of interest a year.
What salvage value and ownership period should I use?+
Salvage is the resale value at the end of your ownership period, entered as a percent of list price. Tractors hold value well (often 25–40% after 10–12 years); combines and tillage tools depreciate faster. The ownership period is how long you plan to keep it before trading; spreading depreciation over more years lowers the annual charge but means the machine is older and repairs are higher — the ASABE repair law captures that trade-off.
Is this for self-propelled machines or implements too?+
Both. For a tractor or combine, rated PTO power drives the fuel calculation directly. For a drawn implement (plow, planter, baler), enter the power needed to pull it and the tool charges the pulling tractor's diesel against the implement's job. The repair factors in the dataset are per implement class, so a moldboard plow (RF1 0.34) and a round baler (RF1 0.43) get their own repair curves.
What is a typical operating cost per acre for a combine?+
It varies enormously with size, price and acreage, but a self-propelled combine commonly lands in the range of $20–40 per acre all-in (fixed + variable) when used on a few hundred acres a year, dropping as acreage rises. The figure this tool gives is specific to your price, power, diesel price and utilisation, so use it rather than a rule of thumb — and compare it against the published custom-combining rate for your region.
How does this differ from a simple percentage-based estimate?+
Most quick machinery calculators apply a rough flat percentage of price for repairs (say 5%) and ignore how repairs accelerate with hours. This tool applies the ASABE RF1/RF2 power law, so an old combine's repair cost is realistically higher than a new tractor's, and it sizes fuel from rated PTO power rather than guessing. That produces a per-hour number you can defend to a lender, partner or custom-hire negotiation.
Does the tool store my numbers?+
No. Everything runs entirely in your browser — nothing is uploaded or saved on a server. Your machine prices, fuel costs and acreage stay on your device, which matters when you are working out the economics of your own operation.
What does the repairs-per-hour figure include?+
It is maintenance and repair — parts and shop labour to keep the machine running: filters, belts, bearings, hydraulics, engine and driveline work, tyres on a wear basis. It does not include the operator's wage (that is the labour line) or fuel and lube (the fuel and lube lines). Because it comes from the ASABE accumulated-repair curve divided by useful-life hours, it reflects the machine's whole-life repair burden averaged to an hourly rate.