Guide

How to Choose Excavator Size

An oversized machine cannot manoeuvre and burns fuel; an undersized one cannot finish the job. Size classes, bucket capacities and a selection matrix by job type.

06.08.2026 3 min read

The wrong size costs money in both directions. An oversized machine cannot manoeuvre in tight spaces, costs more to transport and burns more fuel. An undersized one misses the programme and breaks down more often because it is working at its limit.

Size classes

Class	Bucket	Dig depth	Typical work
Mini (1–6 t)	0.02–0.20 m³	2–4 m	Gardens, narrow streets, indoor demolition, cable trenches
Midi (6–10 t)	0.20–0.35 m³	4–4.5 m	Utility runs, small foundations, landscaping
13–16 t	0.45–0.70 m³	5–5.5 m	Trenching, mid-scale foundations
20–25 t	0.80–1.10 m³	6–6.7 m	The workhorse class — general earthworks, utilities, foundations
30–40 t	1.20–2.30 m³	7–7.5 m	Bulk earthworks, rock, truck loading
45 t +	2.50 m³ +	8 m +	Mining, major infrastructure, dams

Productivity formula

Hourly output (m³) = (3600 × bucket × fill factor × efficiency) ÷ cycle time (s)

For a 20-tonne machine: bucket 0.9 m³, fill factor 0.9, efficiency 0.80 (48 working minutes per hour), cycle 18 s →

(3600 × 0.9 × 0.9 × 0.80) ÷ 18 ≈ 130 m³/h in loose volume.

Note that this is loose volume, not bank volume measured in place. The difference matters for haulage planning.

Quick selection

Job	Class
Indoor demolition, tight garden	Mini 1.5–3 t
Urban cable or gas trench	Mini–Midi 5–8 t, or a backhoe loader
Sewer or water main	13–20 t
Building foundation	20–25 t
Road cutting, bulk earthworks	30–40 t
Rock breaking	25 t +
High-tempo truck loading	30 t +

Can the machine reach the site?

The most commonly missed check. A 30-tonne machine moves on a lowbed, and a lowbed cannot enter every street. Confirm access width, turning radius and any bridge or culvert loading before you book.

Attachments push the size requirement up

Do not size the machine on the bucket alone. The attachment you intend to use raises the carrier requirement:

Attachment	Minimum carrier	Note
Standard bucket	Matched to class	—
Hydraulic breaker	~15× the breaker weight	An oversized breaker strains the boom
Screening bucket	One class above standard	High loaded weight
Demolition shear	20 t +	May need a long-reach boom
Vibratory compactor	5 t +	Hydraulic flow must be sufficient

A common and expensive mistake is fitting a 20-tonne-class breaker to a 14-tonne machine. It will strike, but the boom and undercarriage are overloaded — and the resulting damage counts as misuse, which insurance does not cover.

Zero tail swing and short tail

Zero tail swing: the upper structure stays within the track width when slewing. Safe against a wall or in a narrow street.
Short tail: overhangs slightly. More powerful than zero tail for the same class.
Standard: significant overhang. Fine in open ground, hazardous in confined space or beside live traffic.

If you will work in a city street, beside an existing structure or next to an open carriageway, say so when you request the quote.

Frequently asked

I do not know my volume — how do I estimate it?

Length × width × depth is an adequate start. Break irregular areas into rectangles and sum them. Remember to add the batter allowance and the swell factor before you plan haulage.

Would a smaller machine over a longer period be cheaper?

Usually not. The rate falls but the duration rises, operator days increase and transport stays the same. A machine working at its limit also breaks down more often. The correct class is normally the cheapest class.

Two medium machines or one large one?

If the site can accommodate both working at once, two medium machines are more resilient: a breakdown does not stop the works, and you can run parallel fronts. In a single confined excavation, one larger machine is more productive.

Who confirms the machine can reach the site?

Access is the hirer\'s responsibility. If in doubt, send photographs of the access road and the unloading area — far cheaper than a wasted delivery trip.

Written by: Matyol İnşaat teknik ekibi · Technically reviewed by: Yılmaz MATUR

This article is for general guidance. Binding figures and terms are those in the written quote.

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