Petrol Post Hole Digger Guide: Auger Size and Engine Power
Digging fence post holes by hand is a full day's work you don't need to sign up for. A petrol post hole digger with the right auger size and engine power turns it into an afternoon job — here's how to choose one.
Auger size matches the job, not your strength
Auger diameter should match what you're actually installing — a 150mm auger suits standard fence posts and light landscaping, while wider augers are needed for larger posts or footings. Buying oversized doesn't help; a bigger auger just needs more engine power to turn through the same ground.
Engine power for your ground type
Softer soil and established garden beds are manageable with a smaller 38–62cc engine. Once you're dealing with clay, compacted ground, or rocky soil, step up to 75–88cc — the extra torque is the difference between powering through and stalling out every few centimetres.
Extension shafts for depth
Standard shaft length covers most fence post depths, but a 600mm extension shaft is worth having if you're digging for deeper footings or taller posts — cheaper to buy once than to discover mid-job you're short.
Two-person vs single-person units
Larger diggers are genuinely a two-person job — one person controls the throttle while the other steadies the auger. If you're working solo regularly, a lighter single-operator unit with a smaller auger will save a lot of frustration, even if it means more passes for wider holes.
Browse the full range in Post Hole Diggers.
For general workplace equipment safety guidance, see Safe Work Australia.
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About the author: Ryan Griffiths is based in Newcastle, NSW, and works with the Toolaroo team helping tradies, farmers, and home workshop owners choose the right storage and equipment for their setup.