Picking an excavator that is too small slows the job and strains the machine. Picking one that is too big wastes money, damages ground and may not fit through the gate. The good news: three questions narrow the choice quickly.
1. How deep and how wide do you need to dig?
Dig depth is the first filter. As a rough guide, compact machines of 1.7 to 3 tonnes reach about 2.2 to 2.8 metres, mid-size machines of 5 to 8 tonnes reach about 3.5 to 4.5 metres, and crawler excavators of 13 tonnes and above comfortably exceed 5 metres. Trench width matters too — match the bucket to the trench rather than digging twice with a narrow bucket.
2. How much material are you moving?
For a few cubic metres of service trench, a mini excavator is ideal. For house foundations or a swimming pool, a 5 to 8 tonne machine keeps pace with a dump truck. For basements, road cuttings and bulk earthworks, a 20 tonne class excavator moves material many times faster and usually works out cheaper per cubic metre, even though the day rate is higher.
3. What are the access and ground conditions?
- Gate and path width: some 1.7 tonne machines pass through openings under a metre wide.
- Overhead limits: cables, branches and indoor ceilings may rule out larger booms.
- Ground bearing: soft ground favours wider tracks and lighter machines, or timber mats.
- Finished surfaces: rubber tracks protect paving, lawns and floors.
- Tail swing: zero or reduced tail swing models are safer next to walls and traffic.
Quick reference
| Machine class | Typical dig depth | Good for |
|---|---|---|
| 1.7 – 3 t mini | 2.2 – 2.8 m | Gardens, service trenches, indoor work |
| 5 – 8 t midi | 3.5 – 4.5 m | House footings, drainage, pools |
| 13 – 20 t crawler | 5.5 – 6.5 m | Basements, bulk dig, loading trucks |
| 25 – 30 t crawler | 6.5 – 7 m | Large earthworks, quarry and demolition |
Do not forget attachments
A hydraulic breaker turns an excavator into a demolition tool; a grading bucket gives a clean finish on slopes; an auger drills post and pile holes. Ask for the attachments when you book so they are tested with the machine before delivery.
Still unsure?
Tell our team the task, the depth, the access and the soil. We will recommend a size and explain why — so you pay for exactly the machine the job needs. Request a quote or browse our equipment fleet.