How Bilby works
How Bilby calculates driveway costs
An installed driveway estimate
Bilby measures your drawn driveway and prices its selected surface with normal formation and professional installation. One driveway package owns the cost. Excavation, aggregate, compaction, surfacing and ordinary edging displayed beneath it describe that package and are not five extra contracts.
Six surface choices
Choose prepared base, gravel, compacted gravel, asphalt, paving stone or vehicle-bearing concrete. Prepared base stops before a finished surface. Extra edging, gates, special drainage, lighting and entrance upgrades remain separate when selected. Rock, major soil replacement, unstable ground or excessive grade fall outside ordinary native construction and require review. A provisional fallback does not confirm that the site is straightforward.
Compare the installed surface specifications
The native area rates and minimums below are low / expected / high, including VAT. Minimums explain why very small areas do not scale linearly. Fallback reference amounts can differ and are identified in the actual receipt.
| Surface | SEK/m² | Minimum SEK |
|---|---|---|
| Prepared base | 250 / 400 / 600 | 18,000 / 25,000 / 35,000 |
| Gravel | 350 / 500 / 700 | 20,000 / 30,000 / 45,000 |
| Compacted gravel | 350 / 500 / 700 | 20,000 / 30,000 / 45,000 |
| Asphalt | 500 / 700 / 900 | 25,000 / 35,000 / 50,000 |
| Paving stone | 800 / 1,100 / 1,500 | 25,000 / 40,000 / 60,000 |
| Vehicle-bearing concrete | 1,500 / 2,100 / 2,800 | 35,000 / 55,000 / 80,000 |
Route, width and area
Length follows the planner route; width and geometry determine priced area. Curves, overlaps and ownership can make the net geometry quantity differ from a rough length-times-width estimate.
| Input | Unit | Where from? |
|---|---|---|
| Route | m | Measured planner geometry |
| Width | m | Your control value |
| Priced area | m² | Derived geometry |
| Surface | material | Your selection |
| Ground and slope | conditions | Analysis and terrain warnings |
Area price with a minimum
Native gravel cost = max(minimum, area × rate). Low/expected/high rates are SEK 350 / 500 / 700 per m², with minimums 20,000 / 30,000 / 45,000. Asphalt uses 500 / 700 / 900 and minimums 25,000 / 35,000 / 50,000. Paving uses 800 / 1,100 / 1,500; prepared base 250 / 400 / 600; concrete 1,500 / 2,100 / 2,800. Each has its own minimum. Compacted gravel currently uses ordinary gravel in the native model, although fallback references distinguish them. The method in your details controls the result.
Illustrative 60 m² gravel driveway
A fictional straight 20 m route, 3 m wide, gives 60 m². Native gravel is max(20,000, 60 × 350) = SEK 21,000 low; max(30,000, 60 × 500) = 30,000 expected; max(45,000, 60 × 700) = 45,000 high. The high minimum applies. Doubling a small area therefore need not double the bill. Optional extras are excluded here.
From plan to quotation
Geometry and surface change cost; a cosmetic colour does not imply a separately priced operation. Prices are 2026 consumer allowances including VAT, before tax deductions. They are scenarios, not probabilities. Keep the planner receipt when replacing the allowance with a contractor price so that shared excavation and extras can be reconciled.
Method and review
Method reviewed 18 October 2026: installed planner models active from 4 September 2026 and fallback catalogue researched 16 September. Machine costs are only one part of installed construction Sanmab. These coefficients are Bilby model assumptions, not that supplier’s driveway quote.
The review date covers this explanation and its implemented method. Price and data dates are stated separately in the article.