Convert millimetres to metres instantly for concrete thickness, construction dimensions, drawings, engineering notes, fabrication, landscaping and everyday metric measurements. Enter a value, press Convert, and see metres together with centimetres, millimetres and feet.
The main mode converts millimetres directly to metres. Reverse and supporting modes are included so you can move between common metric and construction length units from the same calculator.
Your conversion will appear here after you press Convert Length.
The PDF includes the entered value, conversion direction and equivalent length in millimetres, metres, centimetres and feet.
The metric system is decimal. One metre contains exactly 1,000 millimetres, so converting millimetres to metres only requires moving three decimal places to the left or dividing by 1,000.
See the main metric relationships together so concrete thicknesses, construction dimensions and general measurements are easier to compare.
Useful for slab thickness, reinforcement cover, fixings, joints and detailed dimensions.
Useful for larger lengths, areas, project dimensions and concrete volume calculations.
See the intermediate metric length where 10 millimetres equals 1 centimetre.
Compare the metric measurement with a common U.S. customary construction length unit.
Convert metres back to millimetres without opening another calculator.
Save the input and converted measurements for quick project reference.
A millimetres to metres conversion is one of the most common metric calculations in concrete estimating, construction drawings, engineering notes, fabrication and everyday measurement. The relationship is exact: one metre contains 1,000 millimetres. To convert millimetres to metres, divide the millimetre value by 1,000.
Metres = Millimetres ÷ 1,000
For example, 100 mm equals 0.1 m, 500 mm equals 0.5 m, 1,000 mm equals 1 m and 2,500 mm equals 2.5 m. Because the metric system is decimal, the same result can also be found by moving the decimal point three places to the left.
Concrete drawings often mix metre-scale project dimensions with millimetre-scale details. A slab might be 6 metres long and 4 metres wide while its thickness is shown as 100 mm. To calculate volume in cubic metres, all three dimensions need to use metres. That means the 100 mm thickness becomes 0.10 m before multiplying length × width × depth.
This is why millimetres-to-metres conversion matters in practical concrete estimating. The arithmetic is simple, but using the wrong scale can create a result that is 1,000 times too large or too small. A thickness of 125 mm is 0.125 m, not 125 m and not 1.25 m.
| Millimetres | Metres | Centimetres | Feet |
|---|---|---|---|
| 1 mm | 0.001 m | 0.1 cm | 0.003281 ft |
| 10 mm | 0.010 m | 1 cm | 0.032808 ft |
| 25 mm | 0.025 m | 2.5 cm | 0.082021 ft |
| 50 mm | 0.050 m | 5 cm | 0.164042 ft |
| 75 mm | 0.075 m | 7.5 cm | 0.246063 ft |
| 100 mm | 0.100 m | 10 cm | 0.328084 ft |
| 125 mm | 0.125 m | 12.5 cm | 0.410105 ft |
| 150 mm | 0.150 m | 15 cm | 0.492126 ft |
| 200 mm | 0.200 m | 20 cm | 0.656168 ft |
| 250 mm | 0.250 m | 25 cm | 0.820210 ft |
| 500 mm | 0.500 m | 50 cm | 1.640420 ft |
| 1,000 mm | 1.000 m | 100 cm | 3.280840 ft |
| 1,500 mm | 1.500 m | 150 cm | 4.921260 ft |
| 2,000 mm | 2.000 m | 200 cm | 6.561680 ft |
| 2,500 mm | 2.500 m | 250 cm | 8.202100 ft |
| 3,000 mm | 3.000 m | 300 cm | 9.842520 ft |
The reverse calculation is just as simple. Multiply metres by 1,000. This is useful when a project dimension is given in metres but a detail, product specification or drawing note expects millimetres.
Millimetres = Metres × 1,000
For example, 0.1 m equals 100 mm, 0.6 m equals 600 mm, 1.2 m equals 1,200 mm and 3.75 m equals 3,750 mm.
There are 10 millimetres in one centimetre. Divide millimetres by 10 to get centimetres. This gives a convenient middle scale between detailed millimetre measurements and metre-scale project dimensions. For example, 150 mm is 15 cm and 0.15 m.
For metric-to-U.S. comparisons, one foot is exactly 304.8 mm. Divide millimetres by 304.8 to get feet. A 1,000 mm length is approximately 3.28084 ft, while 2,000 mm is approximately 6.56168 ft. If you need a dedicated imperial conversion, use the Feet to Metres or related ConcreteCreek length converters.
Concrete thickness is commonly noted in millimetres. Converting the thickness to metres is essential when you calculate cubic metres from area. If a slab covers 40 m² and is 100 mm thick, convert 100 mm to 0.10 m, then multiply 40 × 0.10 to get 4.0 m³ before any waste allowance.
| Concrete Thickness | Thickness In Metres | Volume Per 10 m² | Volume Per 50 m² |
|---|---|---|---|
| 75 mm | 0.075 m | 0.75 m³ | 3.75 m³ |
| 100 mm | 0.100 m | 1.00 m³ | 5.00 m³ |
| 125 mm | 0.125 m | 1.25 m³ | 6.25 m³ |
| 150 mm | 0.150 m | 1.50 m³ | 7.50 m³ |
| 175 mm | 0.175 m | 1.75 m³ | 8.75 m³ |
| 200 mm | 0.200 m | 2.00 m³ | 10.00 m³ |
Use a dedicated Concrete Thickness Calculator or Concrete Volume Calculator when you need the complete project quantity rather than a unit conversion alone.
100 mm equals 0.1 m. This is a particularly common construction conversion because 100 mm is frequently encountered as a drawing dimension, layer depth or slab thickness. The conversion is 100 ÷ 1,000 = 0.1.
150 mm equals 0.15 m. For a 20 m² area, a uniform 150 mm depth would represent 3.0 m³ because 20 × 0.15 = 3.0.
200 mm equals 0.2 m. The same length can also be written as 20 cm or approximately 0.65617 ft.
250 mm equals 0.25 m, which is one quarter of a metre. This makes it easy to recognise mentally: four 250 mm lengths placed end to end equal 1 metre.
500 mm equals 0.5 m, or half a metre. It also equals 50 cm and approximately 1.64042 ft.
1,000 mm equals exactly 1 metre. This is the fundamental relationship used by the converter.
1,500 mm equals 1.5 m. If the same dimension is shown in centimetres it is 150 cm.
2,000 mm equals 2 m. This is approximately 6.56168 ft.
2,400 mm equals 2.4 m. Dimensions around this scale are common in construction layouts, sheets, panels and room-height references, though the actual required dimension always depends on the project.
3,000 mm equals exactly 3 m. Moving the decimal three places left changes 3000.0 to 3.000.
The SI prefix “milli” represents one thousandth. A millimetre is therefore one thousandth of a metre. Stated another way, 1 mm = 0.001 m. Multiplying a millimetre value by 0.001 gives the same result as dividing it by 1,000.
Metres = Millimetres ÷ 1,000 = Millimetres × 0.001
A common error is moving the decimal the wrong number of places. Millimetres to metres requires three decimal places, not one or two. For example, 75 mm is 0.075 m. Writing 0.75 m would mean 750 mm, which is ten times larger. Writing 0.0075 m would mean 7.5 mm, which is ten times smaller.
For a rectangular concrete slab calculated in cubic metres, length, width and depth should all be expressed in metres before multiplication. Suppose a slab is 5.5 m long, 3.2 m wide and 120 mm thick. Convert the thickness: 120 mm ÷ 1,000 = 0.12 m. The base volume is then 5.5 × 3.2 × 0.12 = 2.112 m³.
The same rule applies to strip footings where width and depth may be shown in millimetres while total length is shown in metres. Convert the width and depth to metres first, then multiply. For post holes, convert diameter and depth consistently before using the cylinder formula.
Formwork drawings can include detailed millimetre dimensions while site layout uses metres. Converting between the units helps keep dimensions consistent, but a conversion calculator does not replace dimensional tolerances, structural details or construction drawings. Always work from the current approved project documents.
Reinforcing bar sizes, spacings and concrete cover are often described in millimetres. These values usually do not need to be converted when following a drawing, but conversion can help when checking overall geometry or entering dimensions into software that expects metres. The calculator simply changes units; it does not specify reinforcement, spacing or cover requirements.
Excavation and base-course depths are frequently measured in millimetres while the length and width of the excavation may be in metres. If you are calculating cubic metres of excavation, convert the depth to metres. For example, a 75 mm layer over 100 m² is 0.075 × 100 = 7.5 m³ before compaction or other adjustments.
Mulch, gravel, soil and base layers may be specified by millimetre depth across a square-metre area. The same conversion applies. A 50 mm layer is 0.05 m deep, so 60 m² × 0.05 m = 3 m³ of geometric volume. Material settlement, compaction and supplier factors can change the practical order quantity.
The number fields use a placeholder rather than a pre-filled zero. Visually the field starts with a faint 0, but the actual input is empty. If you type 5, it becomes 5 rather than 05. This keeps data entry clean and avoids forcing you to delete an example number before entering your own measurement.
For many site measurements, three decimal places in metres are enough to retain exact whole-millimetre information. For example, 123 mm becomes 0.123 m. If the original millimetre measurement includes decimals, such as 123.5 mm, then the metre result is 0.1235 m. Keep enough decimal places to preserve the precision of the original measurement.
An exact unit conversion cannot make an approximate site measurement more accurate. If a depth is estimated as about 100 mm, converting it to 0.100000 m does not create extra real-world precision. Measurement accuracy, surface variation, excavation tolerances and construction tolerances remain separate from the mathematical unit conversion.
For broader metric planning, use the Metres to Feet, Feet to Metres, Square Yards to Square Metres or Cubic Yards to Litres converters. For concrete projects, continue with the Concrete Quantity Calculator, Concrete Pouring Calculator or Concrete Price Calculator.
A quick comparison of the exact metric relationships and a useful imperial equivalent.
Exactly one thousand millimetres.
Exactly one hundred centimetres.
The base SI unit of length.
Approximate feet in one metre.
Quick answers to common mm-to-m conversion questions.
Divide the millimetre value by 1,000. For example, 250 mm ÷ 1,000 = 0.25 m.
There are exactly 1,000 millimetres in one metre.
100 mm equals 0.1 m.
150 mm equals 0.15 m.
200 mm equals 0.2 m.
250 mm equals 0.25 m.
500 mm equals 0.5 m.
1,000 mm equals exactly 1 metre.
1,500 mm equals 1.5 metres.
2,000 mm equals 2 metres.
Multiply metres by 1,000. For example, 2.4 m equals 2,400 mm.
Divide millimetres by 10. For example, 125 mm equals 12.5 cm.
If you calculate concrete volume in cubic metres, thickness must also be in metres before multiplying length × width × depth.
The zero is only a placeholder. The field is actually empty, so typing 5 produces 5 rather than 05.
Yes. Press Convert Length first, then use Download Result PDF.
Use recognised SI references when you need formal definitions and conversion guidance.
Official U.S. National Institute of Standards and Technology information on SI length measurement and the metre.
Read NIST Length GuidanceThe International Bureau of Weights and Measures publishes the International System of Units and SI prefix definitions.
View The SI BrochurePractical guidance on SI unit symbols, prefixes and measurement expression.
Open NIST SP 811Use project calculators after converting dimensions to estimate volume, bags and cost.
Open Concrete Volume Calculator