Attachment answers / Sizing & fitment
What size bucket do I need for my excavator?
Short answer
Pick bucket width by the job, then check it against your machine's weight class. A 3-4.5 t mini runs 12-30 in. buckets; a 10-15 t excavator runs 30-48 in.; a 33-55 t machine runs 54 in. and up.
Last reviewed August 2026 · Quarrymark Attachments sales engineering desk
Two rules decide bucket width, and they pull in opposite directions. The job wants the widest bucket that still cuts a usable profile, because width is cycle time. The machine wants the narrowest bucket that does the work, because every extra inch of width and every extra pound of steel is load hung at the end of the stick, where the machine has the least leverage.
The resolution is the weight class. An attachment built for a 10-15 t excavator has the plate thickness, side-plate height and pin-boss size that a 10-15 t machine's breakout force and lift capacity can actually drive. Put that same bucket on a 6 t machine and you have a bucket the machine can fill but cannot lift full. Put a 6 t bucket on a 15 t machine and you will fold the side plates inside a season.
Start from the trench, not the catalog
Utility work is specified by the trench, not by preference. A 12 in. trench for a 4 in. sewer lateral wants a 12 in. trenching bucket, full stop - a wider bucket means more spoil to move, more bedding stone to buy back, and more restoration to pay for. Bulk excavation, footings and loading trucks want the widest digging bucket the class supports. Finish grading and ditch cleanout want a toothless ditching bucket, which is a different tool entirely.
Where operators go wrong is buying one bucket to do all three. A 24 in. general-purpose bucket is a compromise at every one of those tasks, and on a machine that runs a quick coupler the second bucket pays for itself in a few weeks of restoration savings alone.
Then check the class
Every Quarrymark bucket carries its operating-weight window in the product name, because that window is the specification. The table below is the working range across our own excavator and mini-excavator bucket catalog, so it reflects what we actually build rather than a generic chart.
Two things the width chart will not tell you
Material density outranks width. A 48 in. bucket in wet clay carries far more weight than the same bucket in dry sand, and lift capacity is rated at a reach and a height, not as a single number. If you dig heavy material at full reach, size down one step.
Bucket capacity is quoted either struck or heaped, and the two differ by roughly 15-20%. A heaped rating flatters the bucket. When you compare two buckets, compare the same rating, and compare the empty weight too - that weight is subtracted from your lift capacity on every single cycle.
| Machine class | Typical pin Ø | Trenching | Digging / GP | Ditching / grade |
|---|---|---|---|---|
| 1-2 t compact | 25-30 mm | 6-12 in. | 12-18 in. | 30-36 in. |
| 2-4 t mini | 35-40 mm | 6-12 in. | 18-24 in. | 36-42 in. |
| 4-6.5 t mini | 45 mm | 12-18 in. | 24-30 in. | 42-48 in. |
| 7-10 t midi | 50 mm | 12-18 in. | 18-36 in. | 48-60 in. |
| 10-15 t | 60-65 mm | 18-24 in. | 30-48 in. | 60-72 in. |
| 16-25 t | 80 mm | 18-24 in. | 24-48 in. | 72 in.+ |
| 25-36 t | 90 mm | 24 in. | 42-54 in. | 72 in.+ |
| 33-55 t | 90-100 mm | 24-30 in. | 54 in.+ | 84 in.+ |
Ranges are the actual tonnage bands and pin diameters carried across the Quarrymark excavator and mini-excavator bucket catalog. Pin diameter is the typical value for the class - confirm yours against your OEM spec sheet before ordering.
Can I run a bucket from a bigger weight class on my machine?
Physically it may pin up, but it will be heavier than the machine is rated to carry at reach and will slow every cycle. The bigger risk is stability: the extra weight sits at the end of the stick, which is where tipping load is lowest. Size to your class.
Does a quick coupler change what bucket size I should buy?
Yes, slightly. A coupler adds roughly 100-400 lb and moves the bucket 2-4 in. further from the stick pin, which costs a little breakout force and lift at reach. On a machine near the top of its bucket range, that is a reason to stay one size down.
How do I know what my machine's weight class is?
Use the operating weight from your OEM spec plate, in metric tonnes. Operating weight already includes the standard bucket, an operator and a full fuel tank, which is the same basis our tonnage bands use.
