Bucket width is the number most buyers guess at – and the one most often regretted. Too narrow and the job takes twice as long; too wide and a mini excavator cannot fill the bucket or lift it once full. This guide explains how width, capacity and machine tonnage fit together, with the KaiVoy range as a worked example.
The rule: bucket volume against machine class
Excavator manufacturers publish a maximum bucket capacity per machine. On mini machines the practical limit is usually not the lift capacity of the full bucket but whether the machine can breakout and curl a heaped bucket in hard ground. As a starting point for general excavation in average soil:
| Machine class | Typical digging bucket width | KaiVoy digging bucket |
|---|---|---|
| 1.0 – 1.8 t | 400 – 450 mm | UT-430 (430 mm), UT-430 heavy duty |
| 1.5 – 2.5 t | 500 – 520 mm | UT-520 (520 mm) |
| 3.5 t | 600 – 620 mm | UT-620 (620 mm) |
| 5 t | 700 – 720 mm | UT-720 (720 mm) |
| 8 t | 800 mm and up | UT-800 (800 mm) |
Width vs production
- Trenching for services: choose width by the trench spec, not the machine. A 300 mm trench on an 8 t machine needs a narrow, heavy-duty bucket – ask us rather than re-using a wide digging bucket.
- Bulk excavation: widest bucket the machine can fill consistently. Production scales nearly linearly with width until the machine runs out of power.
- Hard rock or frost: step one width class narrower and accept the extra passes, or fit a ripper / scarifier ahead of the bucket.
Grading buckets run wider
Grading (finishing) buckets are wider and shallower than digging buckets of the same machine class – they carry material across a flat floor rather than penetrate it. In the KaiVoy range, the same machine classes carry grading buckets from 800 mm on 1 – 1.8 t up to 1400 mm on 8 t. Keep both on hand: the digging bucket digs, the grading bucket dresses.
Coupler interface is part of the size
Every KaiVoy bucket is welded up for a specific coupler code – S30-180, S40 or S45 in our range. Order the right code for your hitch or the bucket will not lock on. The mapping of every SKU to interface, width and weight is on the specifications page, and we confirm fitment against your machine model before quoting.