I'd like to be able to estimate better how much time a LEGO set will take me to build. Are there any resources online that indicate average or fastest building times for a given set? I suppose it also depends on type of set (for younger or for adult builders, Technic or System,...) What would be your estimate given the amount of elements in a set and type of set?
As others have said, there are probably too many factors to say how long a build will take. But, I thought it would be good to compile a list of factors that affect build time. Feel free to add to the list.
The Lego building process can be divided into two sub-processes; searching, and assembly.
Factors that affect searching time:
- Number of parts in the pile (mixing numbered bags will increase searching time)
- Experience of elements and colours
- Any prior sorting of parts by size/colour (will have an overhead time cost, so only useful for large builds)
- The distribution of parts (having many unique parts will take longer)
- Eyesight and lighting
- If the set is incomplete it can take considerable time to realise
Factors that affect assembly time:
- Number of steps
- Experience (both of the specific set and in general)
- Building of symmetric/repeated sections in parallel
- Build complexity
- Dexterity and hand-eye coordination
- Errors in Lego instructions (very occasional)
I am not sure it is possible to give specific guidance based on simple characteristics like part count or theme. In addition to the factors of the person (or people) undertaking the build raised in the comments, design also makes for wildly different building times.
For example, any set that has bilateral symmetry can be built comparitively quickly by building both sides at the same time even if they mirror each other. Sets that are not symmetrical will often take nearly twice as long. Another more obvious example is the use of advanced techniques that can sometimes make build time much longer, sometimes can drastically reduce complexity and build time, and sometimes have no effect.
Set type and part count do not take account of either those or similar factors like modularity and inclusion of large parts like BURPs or chassis. Labeled age range and part count can probably, at best, simply give a relative indication and no more.
I haven't checked how long it takes my 7 years old daughter based on number of pieces, but I saw she needs about 5 minutes per EUR of the set (with set prices in 20-50 EUR range; Friends mostly). This is for a new freshly opened set.
So, I would guess about 2 min/EUR for an adult that has built some sets but isn't a Lego fanatic. I haven't actually timed myself, though. So, I estimate a 10 EUR set would take about 20 minutes to build, a 100$ one would take slightly more than 3 hours etc.
Transferring these numbers to number of pieces per hour, at 10c/piece it gives ~300 pieces/hour. This sounds reasonable enough to me at first glance, but it is a fairly inaccurate method - though I believe all such estimation methods are.
Note this is only for assembly. Old large sets are slightly slower as all pieces are mixed together instead of being in bags, but it probably shouldn't slow you down too much. But if you need to find pieces with many sets mixed together, well, 10 sets is a problem, 100 is a nightmare. You should probably sort pieces first (by color, type or whatever else you prefer). And after sort you are still looking at a much longer build.
First you need to sort the pieces. So lets say you can sort 12 pieces per minute, then you later need to find them which is probably 6 pieces per minute and assemble them like 3 pieces per minute. So in total you need 7 minutes for 12 pieces. So in 4 hours you can do about 400 pieces.
It is a veeery rough estimate.