Scale Converter

Online Scale Converter

Free online scale converter and scale calculator. Convert real size to model size and back for model trains, die-cast cars, architectural drawings, floor plans and maps, in metric or feet and inches. Answers update as you type.

1What do you want to work out?

What do you want to work out?

2Enter your measurements

Measuring

Choose ft or in to type feet and inches, like 5'11". Several sizes? Type 120 x 60 x 75

Or type any scale, like 1:87, HO or 1/4" = 1'

3Your answer

Model size

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Fill in the fields to see the result.

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    Printable scale ruler

    Print at 100% (turn off “fit to page”), then check the 100 mm bar with a real ruler. Metric marks run along the top edge, feet along the bottom.

    Guide

    How it works

    Three steps, whatever you are scaling: a model train, a die-cast car, a floor plan or a hiking map.

    1. 1

      Choose what to work out

      Pick model size, real size, the scale of a model, change scale or map distance.

    2. 2

      Enter a size and a scale

      Type a size in any unit, such as 4.5 m, 30 cm or 5′11″, and a scale such as 1:24, HO or 1/4″ = 1′.

    3. 3

      Read the answer

      It appears as you type, in every other unit and in fractions of an inch, with a printable ruler.

    The formulas

    A scale of 1:N means one unit on the model stands for N of the same unit in real life. Every answer here uses one of these rules:

    Real size to model size

    model = real ÷ scale number

    A 4.5 m car at 1:24 is 4.5 ÷ 24 = 18.75 cm.

    Model size to real size

    real = model × scale number

    A 20 mm figure at 1:87 is 20 × 87 = 1.74 m.

    Find the scale

    scale number = real ÷ model

    A 1.8 m person shown 25 mm tall is 1800 ÷ 25 = 1:72.

    Model, architectural and map scales built in

    Model railways (Z, N, TT, HO, OO, O and G), die-cast cars (1:18, 1:24, 1:43 and 1:64), plastic kits and wargaming (1:35, 1:48, 1:72 and 1:144), architecture and engineering (1:20, 1:50, 1:100 and 1/4″ = 1′) and maps (1:25,000, 1:50,000 and 1 inch to the mile). You can also type any scale of your own.

    Some examples: a 1.8 m figure is 20.7 mm tall in HO, a 4.5 m car is 10.5 cm long as a 1:43 die-cast, and a 12 m floor plan at 1:50 is 24 cm, small enough for A3.

    Scale converter for models, drawings and maps

    Scale conversion is simple maths, but it is easy to slip up when you switch between millimetres, feet and fractions of an inch. This online scale calculator does the sums for you. Enter a real-world measurement and a scale ratio, and it shows the scaled size straight away. Enter a model or drawing measurement instead, and it works back to the real size. It can also find the scale of a model you already own, or convert a size from one scale to another.

    Model scale calculator for trains, cars and kits

    Model railway builders can pick any standard scale, from Z (1:220) and N (1:160) to TT (1:120), HO (1:87), British OO (1:76.2), O (1:48) and G (1:22.5). Die-cast collectors can convert car sizes at 1:18, 1:24, 1:43 and 1:64, and kit builders and wargamers have 1:35, 1:48, 1:72 and 1:144. Want to know how tall a 6 ft figure should be in HO scale, or how long a real car is as a 1:24 model? Type the size, choose the scale and read the answer in millimetres, centimetres or inches.

    Architectural scale converter for plans and drawings

    Architects, engineers, students and home owners can convert between drawing measurements and real dimensions. Metric drawing scales such as 1:20, 1:50, 1:100 and 1:200 are included, along with imperial architectural scales like 1/8″ = 1′, 1/4″ = 1′ and 1/2″ = 1′, and engineering scales like 1″ = 20′. Results can be shown in feet and inches, with fractions to the nearest 1/16, 1/32 or 1/64 inch, so they match your tape measure. A paper size check tells you whether a floor plan fits on A4, A3 or US Letter, and suggests a drawing scale that does.

    Map scale calculator for distances

    For walkers, cyclists and students, the map distance mode turns a measurement on a map into a real distance on the ground, and back again. It works with common map scales such as 1:25,000 and 1:50,000, the US 1:24,000 topographic series and one inch to the mile (1:63,360). On a 1:25,000 map, 4 cm is 1 km. The calculator does the same sum for any scale and also estimates the walking time.

    Why use this online scale converter

    It is free, there is nothing to install, and it works on phones, tablets and computers. Type sizes the way you would write them, such as 4.5 m, 30 cm, 5′11″ or 12 ft 6 in, and convert length, width and height in one go. A printable scale ruler, areas and volumes, and 3D printer scaling with the slicer percentage are built in too. Every answer is worked out in your browser as you type, so results are instant whichever scale you need.

    Help

    Questions

    Quick answers to what people ask most about model, drawing and map scales.

    01What is an online scale converter?

    A tool that runs in your browser and works out sizes at scale. Enter a measurement and a scale such as 1:24 or HO, and it gives you the model size, the real size or the scale itself, with nothing to install.

    02Is it free?

    Yes. There is no sign-up, it works on phones, tablets and computers, and your numbers never leave your device.

    03Can I convert length, width and height at once?

    Yes. Type the sizes with an x between them, like 4.5 x 1.8 x 1.4 m, and every size is converted together. A 4.5 × 1.8 × 1.4 m car at 1:24 is 18.75 × 7.5 × 5.83 cm.

    04Will my floor plan fit on A3?

    Divide each side by the scale number and compare with the sheet. A 12 m plan at 1:50 is 24 cm long, which fits A3 (42 × 29.7 cm). Choose “Model size”, then open “Will it fit on paper?” to check any sheet and get a scale that fits.

    05What does a scale like 1:87 mean?

    One unit on the model equals 87 of the same unit in real life. So 1 cm on an HO model is 87 cm on the real thing. The bigger the second number, the smaller the model.

    06How do I find out what scale my model is?

    Measure something on the model, like a figure’s height or a car’s length, and find the same measurement for the real thing. Choose “The scale” in the converter, enter both, and it tells you the scale and the closest standard one.

    07How tall is a 6 ft person in HO scale?

    About 21 mm (0.83 in). HO is 1:87, so 6 ft (1.83 m) ÷ 87 = 21.02 mm. Choose “Model size” in the converter to work out any height at any scale.

    08How do I change a model from one scale to another?

    Multiply the size by the old scale number and divide by the new one. A 20 cm model at 1:72 becomes 20 × 72 ÷ 48 = 30 cm at 1:48, so you would print or copy it at 150%. Choose “Change scale” in the converter to do it for you.

    09What is N scale?

    N scale is 1:160 in most of the world and 1:148 in the UK, running on 9 mm track. A 6 ft person is about 11.4 mm tall in 1:160 N scale.

    10What is O scale?

    O scale is 1:48 in North America, 1:43.5 in the UK and France, and 1:45 in Germany. At 1:48, a quarter of an inch on the model stands for one foot.

    11What is the difference between HO and OO?

    Both use the same track, but HO is 1:87 and British OO is 1:76.2. OO models are about 14% bigger than HO models of the same train.

    12How do floor plan scales like 1/4" = 1' work?

    A quarter of an inch on the drawing stands for one foot in real life, which is the same as 1:48. You can type it exactly like that into the scale box.

    13How do I read a map scale like 1:25,000?

    One unit on the map is 25,000 on the ground, so 1 cm is 250 m and 4 cm is 1 km. Choose “Map distance” in the converter to work it out either way.

    14How do I convert a real size to a scale size?

    Divide the real size by the scale number. A 4.5 m car at 1:24 is 4.5 ÷ 24 = 0.1875 m, or 18.75 cm. To go the other way, from a model to real life, multiply by the scale number instead.

    15What is 1:24 scale in inches?

    At 1:24, 1 inch on the model is 24 inches (2 feet) in real life. A 15 ft car is 180 ÷ 24 = 7.5 inches long as a 1:24 model.

    16What is 1:12 scale?

    At 1:12, 1 inch on the model is 1 foot in real life. It is the classic dollhouse scale, so a 6 ft person is 6 inches tall.

    17What does 1:100 scale mean on a drawing?

    1 cm on the drawing is 100 cm, or 1 m, in real life. It is a common scale for building plans: a wall drawn 4.5 cm long is 4.5 m long.

    18How do I convert a scale drawing to real measurements?

    Measure the line on the drawing and multiply by the scale number. On a 1:50 plan, 3.2 cm on paper is 3.2 × 50 = 160 cm, or 1.6 m. Choose “Real size” in the converter and it does the sum for you.

    19Is 1:43 bigger than 1:64?

    Yes. The smaller the second number, the bigger the model. A 4.5 m car is about 10.47 cm long at 1:43 and 7.03 cm at 1:64.

    20What is the difference between scale and gauge?

    Scale is how much smaller the model is than the real thing, like 1:87. Gauge is the distance between the rails of the track. Different scales can share a gauge: HO and OO both run on 16.5 mm track.

    21Is 1:64 the same as S scale?

    Yes. S scale is 1:64, the same ratio used for many small die-cast cars. Hot Wheels and Matchbox cars are roughly 1:64 too, though their sizes vary a little.

    22What scale is a 3¾ inch action figure?

    If the figure represents a 6 ft person, 72 ÷ 3.75 makes it about 1:19, close to 1:18. Choose “The scale” in the converter to check any figure.

    23Can I type feet and inches or fractions?

    Yes. Type it the way you would write it, like 5'11", 12 ft 6 in, 3/4 or 1 1/2 in. Answers can be shown in fractions of an inch too.