Garage Base Calculator: Work Out Your Base Size and Cost
Slide in your size for an instant base cost, plus the simple rule for sizing a garage base and what one typically costs to lay.
Base cost calculator
Estimated base cost
£1,280
8 ft × 16 ft = 128 sq ft
at £10 per sq ft
A quick ballpark only — access, ground conditions and how much digging out is needed all move the real price. Get a written base quote →
A garage base needs to be concrete, completely flat, level and square, a minimum of 100mm (4″) thick, and sized to the building — allow approximately 150mm (6″) extra on both the width and the length over the nominal garage size. Work that out, multiply the two figures, and you have the base area your builder will price against.
How big should my garage base be?
Take the nominal size of the garage you're buying and add roughly 150mm (6″) to the width and 150mm (6″) to the length. That margin covers the building's actual footprint, which comes out slightly larger than the round-number size it's sold as. Add that margin, then set those figures on the calculator above to price a base of that size.
Position matters as much as size. The roof overhangs the walls, guttering adds more, and an Up & Over door swings out roughly 1 metre before returning towards the garage — so think about where the slab sits relative to boundaries, walls and your drive, not just how big it is. New concrete should then cure for at least a week before the building is delivered.
How much does a garage base cost?
As a rough guide, expect £9–£15 per square foot for a straightforward base — that covers concrete, shuttering and labour, but not significant digging out, skip hire or waste removal. Where you land in that range depends on access to the site, how much ground needs removing, the preparation required before the pour, and how local your builder is to the job.
Treat any figure — including the calculator's estimate — as an estimate only. Never go ahead with building work on a verbal agreement: insist on a detailed written quotation, which any reputable builder will provide without question.
Would you like a turn-key price from us?
We lay garage bases ourselves, so you can have the base and the building handled by one company with one point of contact. Read about our concrete base laying service, or request a base quote and we'll price your site properly. Laying it yourself, or using your own builder? Our base laying tips set out the full specification to follow.
Garage base questions, answered
How thick should a garage base be?
A minimum of 100mm (4″) of concrete, and ideally thicker — around 150mm (6″) — at the perimeter of the slab. It must be completely flat, level and square.
Does the base need to be bigger than the garage?
Yes — allow approximately 150mm (6″) extra on the width and the length over the nominal garage size. That covers the building's actual footprint, which is slightly larger than its nominal size.
Can Nucrete lay the base for me?
Yes. We offer a full concrete base laying service, so the base and the building come from one company — request a base quote and we'll price your site.
How soon after laying the base can the garage go up?
The concrete should cure for a minimum of one week before your building is delivered and installed.
Why do base prices vary so much?
Access, ground conditions, how much digging out is needed, and your builder's travel distance all move the price. That's why the £9–£15 per square foot range is only a guide — always get a detailed written quotation before committing.
Written and reviewed by the Nucrete team. The sizing rule and figures here are the same ones our own base teams work to, refined over more than 25 years of laying bases for garage customers.