LEGO® House Calculator
Plan a brick-built house from finished-model dimensions or scaled real-house measurements. Estimate equivalent wall and roof quantities using a selected brick module, subtract repeated door and window openings, and review the exact geometry and assumptions behind the result.
House geometry
The selected module is an area-planning assumption. Wall layers multiply the visible outside wall face; they do not test structural strength or create a brick bond.
Doors and windows
Each door uses the same entered door dimensions, and each window uses the same window dimensions. The estimator subtracts their rectangular areas but does not place them on individual walls.
Roof estimate
A pitched roof uses the combined surface area of two equal slopes without overhangs, gables, ridges, skylights, or support pieces.
Spares, weight, and budget
Currency selection changes the displayed currency only. It does not look up live part prices or convert the entered price using an exchange rate.
Estimated total equivalent pieces
Includes the selected spare allowance.
Wall equivalents
Roof equivalents
Surface-area estimate, not a roof-part inventory.
Spare pieces
Pieces before spares
Estimated weight
Estimated budget
Geometry and module assumptions
Model footprint
Total outside wall height
Planning module
1 equivalent wall layer.
Gross outside wall face
Opening area removed
3.6% of gross wall face.
Net wall face
Roof surface
This is a geometry-based equivalent count. It excludes corners, overlapping bonds, floors, foundations, internal walls, supports, beams, stairs, decorative details, connections, colour availability, and specialised elements.
LEGO® is a trademark of the LEGO Group of companies which does not sponsor, authorize, or endorse this site.
Start With Model Dimensions or a Real-House Scale
Choose finished-model dimensions when you already know the outside length, width, and wall height of the model. These values are used directly after conversion to metres.
Choose scaled real-house dimensions when the measurements describe an actual building. Every entered linear measurement—including doors and windows—is divided by the selected scale denominator.
For example, a 15-metre building length at 1:50 becomes a 0.30-metre model length.
The Result Is an Area-Equivalent Count
The calculator does not design individual brick courses. It divides the visible wall face by the selected module’s nominal long-face area and rounds the result upward.
The selected wall-layer value multiplies that visible-face estimate. It represents equivalent parallel layers, not a structural test or a guarantee that the layers can be connected as entered.
Real construction normally mixes brick sizes, plates, tiles, windows, slopes, supports, hinges, arches, and filler pieces. The result should therefore be treated as a planning quantity rather than an exact shopping list.
Doors and Windows Reduce the Wall Estimate
Gross outside wall face is calculated from the rectangular perimeter, wall height per floor, and number of floors.
The calculator then subtracts the repeated rectangular area of each entered door and window. All doors use the same entered door dimensions, and all windows use the same entered window dimensions.
It rejects an individual opening that is wider than the longest outside wall, taller than the complete wall height, or part of a combined opening area that consumes the entire gross wall face.
Flat and Pitched Roofs Use Surface Area
A flat roof uses the model’s rectangular footprint. A symmetrical pitched roof divides that footprint by the cosine of the entered pitch to estimate the combined area of its two equal slopes.
The roof area is divided by the selected module’s nominal top footprint. This produces roof-equivalent pieces, not a count of actual slopes, tiles, ridge pieces, plates, clips, or supports.
Overhangs, gable faces, valleys, dormers, skylights, gutters, and complex roof shapes are not included.
Spares, Weight, and Cost Are Editable Scenarios
The spare allowance is applied to wall and roof equivalents after both have been rounded. Spare pieces are then rounded upward and added to the total.
Estimated weight uses the average grams per piece entered by the user. Estimated budget uses the entered average price per piece and the currency selected on Olivez.
Different part sizes, colours, conditions, availability, shipping charges, and specialist elements can make a real order substantially lighter, heavier, cheaper, or more expensive.
Turn the Estimate Into a Real Parts Inventory
Use this calculator to test scale, wall area, openings, roof area, and approximate quantity before committing to a detailed build.
Once the dimensions are stable, design the model digitally or section by section. Replace area equivalents with actual elements, corner bonds, openings, roof connections, internal supports, and decorative pieces.
An official parts browser or dedicated digital brick-design tool is more suitable for confirming available elements, colours, and an exact model inventory.
Independent LEGO® Trademark Notice
This independent calculator uses LEGO® only to describe the type of compatible brick model being estimated.
LEGO® is a trademark of the LEGO Group of companies which does not sponsor, authorize, or endorse this site.
Brick-house estimation formulas
All lengths are converted to model metres first. In scaled-real mode, every linear measurement is divided by the scale denominator before any area is calculated.
Formula variables
- Entered real-house length
- Resulting model length
- Scale denominator
- Model length and width
- Model wall height per floor
- Number of floors
- Number of equal-size doors and windows
- Model door width and height
- Model window width and height
- Equivalent wall layers
- Selected module’s nominal long-face area
- Symmetrical roof pitch
- Roof-equivalent pieces
- Spare allowance percentage
Examples
Small house with openings and a flat roof
1Input
Finished model: 30 cm × 20 cm; wall height: 15 cm; one floor; 2×4 module; one 3 cm × 6 cm door; four 3 cm × 3 cm windows; flat roof; 10% spares.
Show result
Result
Gross wall face is 0.15 m² and openings remove 0.0054 m². The estimate produces 474 wall equivalents, 120 roof equivalents, 60 spares, and 654 total equivalent pieces.
At 2.3 g and 0.08 currency units per piece, the scenario weighs approximately 1.50 kg and costs 52.32.
Simple open-top model
2Input
Finished model: 30 cm × 20 cm; wall height: 15 cm; one floor; 2×4 module; no openings; no roof; 10% spares.
Show result
Result
The estimator produces 492 wall equivalents, 50 spare pieces, and 542 total equivalent pieces.
No floor, internal wall, foundation, or support pieces are included.
Scale a real house at 1:50
3Input
Real dimensions: 15 m × 10 m; wall height: 3 m per floor; scale: 1:50.
Show result
Result
The model footprint becomes 0.30 m × 0.20 m and the wall height becomes 0.06 m per floor.
Real door and window measurements are divided by the same scale denominator.
Compare flat and pitched roof area
4Input
Model footprint: 30 cm × 20 cm. Compare a flat roof with a symmetrical 45° pitched roof.
Show result
Result
The flat roof area is 0.06 m². The pitched roof area is approximately 0.08485 m² because the two slopes are longer than their horizontal projection.
The estimate excludes overhangs, ridge construction, and gable walls.
Frequently Asked Questions
Does this produce an exact LEGO® parts list?
No. It converts wall and roof surface areas into equivalent quantities for one selected planning module.
What does wall layer mean?
One layer estimates one module-deep equivalent wall face. Additional layers multiply that area estimate. It is not a structural assessment.
Are floors included in the piece count?
No. The floor count increases wall height, but floor plates, foundations, ceilings, and internal floors are not estimated.
Why are doors and windows subtracted?
Their rectangular areas replace part of the outside wall face that would otherwise be covered by the selected module.
Can every door and window have a different size?
Not in this version. All doors share one entered size and all windows share another entered size.
How is a pitched roof calculated?
The rectangular footprint is divided by the cosine of the roof pitch to estimate the combined surface of two equal slopes.
Does the pitched-roof estimate include gables?
No. It excludes gable triangles, overhangs, ridges, valleys, dormers, and supporting structure.
Why can the actual piece count be higher?
Corners, overlapping brick bonds, supports, floors, decorative details, filler pieces, and specialised elements can all add parts.
Does changing currency convert the price?
No. Currency selection changes the displayed symbol and format. Enter a price per piece already expressed in that currency.
Where can I confirm actual available parts?
Use an official parts browser or digital brick-design tool after creating a real model design.
Is Olivez affiliated with the LEGO Group?
No. LEGO® is a trademark of the LEGO Group of companies which does not sponsor, authorize, or endorse this site.
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