Need help figuring scales

Discussion in 'Tips & FAQs' started by thewoodengraver, Nov 9, 2005.

  1. thewoodengraver

    thewoodengraver Active Member

    I realize I need to know the size of the subject to figure out the scale of the model. But that's all I know about scales. What is the mathematical formula?
    Any suggestions on tutorials via websites or software or formulae will be greatly appreciated. Thanx
  2. lunarhighway

    lunarhighway Member

    scales are not so difficult as it seems.
    only i don't know if i can explain it well, my scientiffic english is a little limited...also i'm only used to the metric system, and i mostely build i'll use those in examples, but that shouldn't be a big problem to convert to whatever you use and build... here we go

    for example if something is 1/33 scale it means that the model is 33 times smaller than the real thing so if you want to make a model of an airplane that has a wingspan of lets say 10 meters you devide 10m by 33 -> 0.303030.... so the model is gonna have a span of 30 cm...

    now to extrapolate the unknown scale of something:

    if you have a model or more common a drawing, but you don't know what scale it is, find an easy distance to measure. On planes this is usually the wingspan... so lets say the drawing has a span of 30cm (A) next you look up the span of the real plane (and preferably use more than one source becouse somethimes there are errors/variations/modifications...wich could end up giving you the wrong end result) let say the real plane was 10m (B)in span.

    so now we have to calculate how many times the model or drawing is smaller than the real thing.

    to do this simply devide the real size by the scale size A/B or 10m =1000cm/30cm = 33.33333333 so the model is 1/33

    if you want to rescale a model...wich i sometimes do. for example you would like to downscale a 1/33 (A)model to 1/72(B)

    simply do: (A/B)*100

    wich is 33/72 = 0.45833333333 *100 = 45.8333 so you have to scale the original model down 46%

    as you see i've rounded the number, wich is extremely very acurate but it doesn't make a visible difference.

    if you want to upscale a model just do the same

    lets say 1/72 to 1/48

    so you do:

    (72/48 )*100=150 so you'll have to upscale 150%

    anyway i hope this helps you along a bit... i'm by no means a mathematical wizard...(and i hope i didn't write a mistake somewhere :p )

    happy scaling :)
  3. Ashrunner

    Ashrunner Member

    I once found several program for calculating scale. Send me a PM with an email address and I will email you one I use most often.

    However, if you prefer, you can use several online calculators. This one allows both up and down scaling.
  4. lizzienewell

    lizzienewell Member

    Measure something on the model that you know the size of in full size. Human figures, doors, or height of building stories are a good thing to look at. If a drawing of a model lacks anything that you know the size of then draw a person next to drawing adjust the size of the person until it looks right and figure the scale from the person.

    I will figure out the scale of my model because I haven't done it yet. I've got a human figure in it that is .41 inches I know that an average adult is 5'8" and an average sized adult man is 5'10", woman 5'6" so I convert both to the same units. I might be slightly off on these numbers but it's all approximate anyway. You might be most comfortable with a photo or drawing of yourself for scale and then use your own height.

    My average adult is 68 inches. I can handle scale several ways. I can divide the smaller number by the bigger .41/68 = .0060 This is useful for multiply the original size of the part to produce the size of the model part. If I want it as a percentage I move the decimal point two places .60 %. In coreldraw I can use this to change scale of parts.
    For a more tradition scale measurement, I divide the larger number by the smaller 68/.41= 1:166. I find the ratio expressed as a decimal or percentage to be the most useful. I hope I got my math right.

    On a related note, I like models to include human figures or indications of human figures such as doors and chairs. This gives scale to the viewers and allow them imagine themselves on the same scale as the model.

  5. wunwinglow

    wunwinglow Active Member

    I prefer to work in meters, or milimeters. I grew up with inches, and fractions of inches, and feet, and yards, and furlongs, and chains, and groats, and ells, and bushels, and stones, and hundredweights (which had 112 pounds in them, go figure...) And the concept of a metric inch; OOOO, my brain hurts!

    Thank you Napoleon Boneparte, for the metric system. Even if you did get the distance from the North Pole to Paris wrong.....

    Tim P
  6. lizzienewell

    lizzienewell Member

    For scale the unit of measurement doesn't mater as long as you use it consistently. A chemistry teacher told me to always mark unit of measurement when doing calculations. In ratios the units cancel out so if you mark them and accidently mixing meters and inchs you will notice because the units won't cancel.
  7. ShipWreak

    ShipWreak New Member

    Heres a little consistancy as far as I understand it....

    Say you want to scale something to 1:24 in inches.

    100 x 12 in.
    ----------- = 1:24 scale

    Hope that was correct ;-P



    life would be simpler if every PDF included the scale and a reference line; particularly models drawn in non-standard scales.....Chip.
  9. thewoodengraver

    thewoodengraver Active Member

    Thanx all,

    All the information submitted helped me understand scales and it looks like I lucked out!, ashrunner (poobah) hooked me up with a friggin piece of software that takes the guesswork (and brainwork) out! (see his post for link) Now I don't have to go into the wayback machine to remember Math!!!
  10. SCEtoAux

    SCEtoAux Member

    Here is another calculator that you can download. It is a small file, easy to use, with a few different conversions.[​IMG]
    Scale Calculator
  11. hpept

    hpept Member

    i completely agree with ringmaster. All would be simpler, and people could immediately measure the graduated strip to see if the printer does its work right. Sometimes during printing little adjustments are made to fit the page, and it can lead to a model in a wrong scale.
  12. SteveM

    SteveM Member

    I work in the disk-drive industry and for a long time the height the read/write head flew above the disk was measured in micro-inches. We've since migrated to using nano-meters partly as a general trend to the metric system but also because we now fly in the range of just a few nm! Most of our test equipment still measures in microinches, though so the magic numbers of 25.4 and 39.37 get used quite extensively 'round here.:)

  13. Ashrunner

    Ashrunner Member

    Thanks SCEtoAux...this is the calculator I sent Woodengraver. I spent quite a while looking for a link to the file and only found dead links for it and one other freeware scaling software product I have.

    At least now, others who want the program can get it 8v)
  14. jleslie48

    jleslie48 Member

    I wrote up my notes from my lecture to 7-8th graders on scale as a faq that I think does a pretty decent job of explaining how scale work:

    see if if makes any sense to you.

    also, If you are so inclined to use excel, I wrote a fairly intricate yet easy to use spreadsheet that helps you document an item (ship,plane, rocket, etc)
    and allow you log all the 1:1 measurments, and then compare them side by side to any two scales you like (1:48, 1:96, 1:1) in any unit of measure. I redo this spreadsheet for each item I make design a model for so I can reference the numbers later, and check scale. Here is an example of my Saturn V spreadsheet:

    with a bunch of the measurements I needed to make the model. I hope it is self-explanitory, but if its not feel free to ask a question or three.
  15. Kaz

    Kaz Member

  16. Leif Oh

    Leif Oh Member

    Download this scaling calculator for your browser

    Browsing a thread here at about Jim Collins' free printable accessories I came across another little gem on his site, namely a calculator for scaling from all sorts of odd scales to other scales.

    Now, the beauty of it all was that you could download and save the whole page to disc, and keep it as a stand-alone calculator accessible in your ordinary browser, but you don't have to be on-line to use it!

    Having done just that, I couldn't, of course, leave well enough alone, but started fiddling with the excellent little calculator to make it better adapted to the needs of card modelers. The result is a very neat little 16 KB - yes, not MB, and it's only 3.4 KB zipped - calculator. (See the attached images and the zip file below.)

    The first image demonstrates a case where you have come across a fact file or a drawing of, for example, an aircraft with the span given as 50 ft, 6 inches, and 3/16 of an inch.

    Enter these values into their proper places, press calculate, and you can immediately read it translated into 15,397 mm.

    But it gets better:

    In the second image, the example is that you wish to know what the span will be in your desired scale of 1:87. Just add that information, press calculate, and you get the result 177.0 mm (after proper rounding). And if you'd rather have the result as 6 inches and 15/16 of an inch, you get that too!

    Now, this is useful - having that information immediately at hand you can easily find the scaling factor for any drawing you have downloaded. Just divide your target span measure of 177.0 mm (in this example) with the span measured from your drawing at hand, multiply with 100 and you get the scaling factor in percent to reach 1:87. This last little calculation you will have to perform on an ordinary pocket calculator, though!

    You can download the calculator below as a zipped html-file. I have purged a number of odd scales, but if you wish for any particular scale which isn't in there, I'll gladly make a new version. Just write a post here in this thread.

    Can I just add that the beauty of this calculator is that it runs in any browser (with basic Java, which means any modern browser), and therefore on any system - PC, Mac, or Linux. And, since you are likely to have your browser running most of the time anyway, there is no need for launching another application - just open a new page in the browser from your file.

    And if you create a bookmark/favourite for your saved file, you'll find yourself really swinging, with a drawing from the net in one tab, a factfile in the next, and your calculator in a third, instantaneously available!


    PS. I first developed this calculator over at, but put it in a thread there which was for members only. Awaiting a change of venue, I'll just post it here in this thread as well. While purging a number of very odd scales, I have added the two common card model scales of 1:33 and 1:250 (which weren't there in Jim Collins' original calculator).

    Attached Files:

  17. SCEtoAux

    SCEtoAux Member

    Thanks, Leif Oh.
    I also saved that calculator from Jim Collin's site to my HD a while back so I could use it off line. I still visit Jim Collin's page, though, because he has a lot of interesting stuff. I even use that calculator on line sometimes too.

    Your changes to the calculator sound useful. I will give it a try.
    Thanks again.:)
  18. Stev0

    Stev0 Active Member

    Yep I gotta agree with this 100/1 percent.
  19. xyberz

    xyberz Member

    I just want to reiterate to make sure that I'm completely understanding your calculations correctly.

    To scale a model down use the following calculation:

    1/60 scaled down to 1/100

    60/100 = 0.60 * 100 = 60

    So I need to scale my model down by 60% to reach 1/100 from 1/60th scale.

    Exact number calculation for people who have to do it manually.

    Model piece 1/60th scale size is 100x100 pixels scaled down 60% would then become 40x40 pixels.
    100 pixels x 0.60 = 60 pixels - 100 = -40 pixels

    Lets do the opposite and scale up.

    1/100 scaled up to 1/60

    100/60 = 1.67 (Rounded up next hundredth digit) * 100 = 167%

    So I need to scale my model up 67% to get from 1/100 to 1/60th scale.

    Model piece 1/100 scale size is 100x100 pixels scaled up 67% would then become 167x167 pixels.
    100 pixels x 0.67 = 67 pixels + 100 pixels = 167 pixels

    I think that's correct right? Please correct my calculations if needed.

    No one really posted the exact calculation of each pixel in case they had to resize the pieces to fit onto the page, just the main percentages.
    The only problem I saw with that is if for instance, the model was a PDF and you wanted to scale up. If you were to scale up a PDF to a considerable amount, your pieces would run off the page and you wouldn't be able to print it out. So your only option then would be to cut and paste the newly resized pieces onto another document or picture format in order for it to fit onto a page to print.
  20. cgutzmer

    cgutzmer Guest

    Would it be possible to get this calculator to tell you the percent that you need to print at to change from one scale to the other? This would assume you know the current scale already and the scale you want to go to. Now that would be perfect for me :) I always think I understand it until someone tries to explain it :)

Share This Page