Metric Threads

The ISO Metric thread is one of the most commonly used type.

The 'M' designation indicates the major diameter of the nut (or nominal outer diameter of a screw or bolt) in millimeters. Typically the thread pitch is quoted too:

M6x1.5

This means it has a 6mm diameter with 1.5 threads per millimeter.

The design principles of ISO general-purpose metric screw threads ("M" series threads) are defined in ISO 68-1. Each thread is characterised by its major diameter and pitch.

The thread is a symmetric V shaped thread with the flanks having an angle of 60°.

Not all of the threads in the following table are preferred types. Some (especially those with fewer pitches defined) are non-preferred sizes. Generally these are very uncommon. However, Trojan has the facility to thread almost any thread size and pitch. Just enquire and we'll take care of your needs.

  Minor Dia Pitch Dia Major Dia Tap Drill
ThreadPitchClassMinMaxMinMaxMinMaxBasic
M3x0.50.56H2.4592.5992.6752.7753.0003.1722.500
M3x0.350.356H2.6212.7212.7732.8633.0003.1412.650
M3.5x0.60.66H2.8503.0103.1103.2223.5003.6992.900
M3.5x0.350.356H3.1213.2213.2733.3633.5003.6413.150
M4x0.70.76H3.2423.4223.5453.6634.0004.2193.300
M4x0.50.56H3.4593.5993.6753.7754.0004.1723.500
M4.5x0.750.756H3.6883.8784.0134.1314.5004.7263.750
M4.5x0.50.56H3.9594.0994.1754.2754.5004.6724.000
M5x0.80.86H4.1344.3344.4804.6055.0005.2404.200
M5x0.50.56H4.4594.5994.6754.7755.0005.1724.500
M5.5x0.50.56H4.9595.0995.1755.2955.5005.6925.000
M6x116H4.9175.1535.3505.5006.0006.2945.000
M6x0.80.86H5.1345.3345.4805.5866.0006.2215.200
M6x0.750.756H5.1885.3785.5135.6456.0006.2405.250
M6x0.70.76H5.2425.4225.5455.6716.0006.2265.300
M6x0.50.56H5.4595.5995.6755.7876.0006.1845.500
M7x116H5.9176.1536.3506.5007.0007.2946.000
M7x0.750.756H6.1886.3786.5136.6457.0007.2406.250
M7x0.50.56H6.4596.5996.6756.7877.0007.1846.500
M8x1.251.256H6.6476.9127.1887.3488.0008.3406.750
M8x116H6.9177.1537.3507.5008.0008.2947.000
M8x0.80.86H7.1347.3347.4807.6208.0008.2557.200
M8x0.750.756H7.1887.3787.5137.6458.0008.2407.250
M8x0.50.56H7.4597.5997.6757.7878.0008.1847.500
M9x1.251.256H7.6477.9128.1888.3489.0009.3407.750
M9x116H7.9178.1538.3508.4989.0009.2928.000
M9x0.750.756H8.1888.3788.5138.6459.0009.2408.250
M9x0.50.56H8.4598.5998.6758.7879.0009.1848.500
M10x1.51.56H8.3768.6769.0269.20610.00010.3968.500
M10x1.251.256H8.6478.9129.1889.34810.00010.3408.750
M10x1.121.126H8.7889.0389.2739.43310.00010.3228.880
M10x116H8.9179.1539.3509.50010.00010.2949.000
M10x0.750.756H9.1889.3789.5139.64510.00010.2409.250
M10x0.50.56H9.4599.5999.6759.78710.00010.1849.500
M11x1.51.56H9.3769.67610.02610.19611.00011.3879.500
M11x116H9.91710.15310.35010.50011.00011.29410.000
M11x0.750.756H10.18810.37810.51310.64511.00011.24010.250
M11x0.50.56H10.45910.59910.67510.78711.00011.18410.500
M12x1.751.756H10.10610.44110.86311.06312.00012.45310.250
M12x1.51.56H10.37610.67611.02611.21612.00012.40610.500
M12x1.251.256H10.64710.91211.18811.36812.00012.36010.750
M12x116H10.91711.15311.35011.51012.00012.30411.000
M12x0.750.756H11.18811.37811.51311.65312.00012.24811.250
M12x0.50.56H11.45911.59911.67511.79512.00012.19211.500
M14x226H11.83512.21012.70112.91314.00014.50112.000
M14x1.51.56H12.37612.67613.02613.21614.00014.40612.500
M14x1.251.256H12.64712.91213.18813.35814.00014.35012.750
M14x116H12.91713.15313.35013.51014.00014.30413.000
M14x0.750.756H13.18813.37813.51313.65314.00014.24813.250
M14x0.50.56H13.45913.59913.67513.79514.00014.19213.500
M15x1.51.56H13.37613.67614.02614.21615.00015.40713.500
M15x116H13.91714.15314.35014.51015.00015.30414.000
M16x226H13.83514.21014.70114.91316.00016.50114.000
M16x1.61.66H14.26814.56814.96115.10116.00016.37114.400
M16x1.51.56H14.37614.67615.02615.21616.00016.40614.500
M16x1.251.256H14.64714.91215.18815.35816.00016.35014.750
M16x116H14.91715.15315.35015.51016.00016.30415.000
M16x0.750.756H15.18815.37815.51315.65316.00016.24815.250
M16x0.50.56H15.45915.59915.67515.79516.00016.19215.500
M17x1.51.56H15.37615.67616.02616.21617.00017.40715.500
M17x116H15.91716.15316.35016.51017.00017.30416.000
M18x2.52.56H15.29415.74416.37616.60118.00018.58515.500
M18x226H15.83516.21016.70116.91318.00018.50116.000
M18x1.51.56H16.37616.67617.02617.21618.00018.40616.500
M18x1.251.256H16.64716.91217.18817.35818.00018.35016.750
M18x116H16.91717.15317.35017.51018.00018.30417.000
M18x0.750.756H17.18817.37817.51317.65318.00018.24817.250
M18x0.50.56H17.45917.59917.67517.79518.00018.19217.500
M20x2.52.56H17.29417.74418.37618.60020.00020.58517.500
M20x226H17.83518.21018.70118.91320.00020.50118.000
M20x1.51.56H18.37618.67619.02619.21620.00020.40618.500
M20x116H18.91719.15319.35019.51020.00020.30419.000
M20x0.750.756H19.18819.37819.51319.65320.00020.24819.250
M20x0.50.56H19.45919.59919.67519.79520.00020.19219.500
M22x336H18.75219.25220.05120.29622.00022.67719.000
M22x2.52.56H19.29419.74420.37620.60022.00022.58519.500
M22x226H19.83520.21020.70120.91322.00022.50120.000
M22x1.51.56H20.37620.67621.02621.21622.00022.40620.500
M22x116H20.91721.15321.35021.51022.00022.30421.000
M22x0.750.756H21.18821.37821.51321.65322.00022.24821.250
M22x0.50.56H21.45921.59921.67521.79522.00022.19221.500
M24x336H20.75221.25222.05122.31624.00024.69821.000
M24x2.52.56H21.29421.74422.37622.62624.00024.61121.500
M24x226H21.83522.21022.70122.92524.00024.51322.000
M24x1.51.56H22.37622.67623.02623.22624.00024.41722.500
M24x116H22.91723.15323.35023.52024.00024.31423.000
M24x0.750.756H23.18823.37823.51323.66324.00024.25823.250
M25x226H22.83523.21023.70123.92525.00025.51323.000
M25x1.51.56H23.37623.67624.02624.22625.00025.41623.500
M25x116H23.91724.15324.35024.52025.00025.31424.000
M26x1.51.56H24.37624.67625.02625.22626.00026.41724.500
M27x336H23.75224.25225.05125.31627.00027.69824.000
M27x226H24.83525.21025.70125.92527.00027.51325.000
M27x1.51.56H25.37625.67626.02626.22627.00027.41725.500
M27x116H25.91726.15326.35026.52027.00027.31426.000
M27x0.750.756H26.18826.37826.51326.66327.00027.25826.250
M28x226H25.83526.21026.70126.92528.00028.51326.000
M28x1.51.56H26.37626.67627.02627.22628.00028.41726.500
M28x116H26.91727.15327.35027.52028.00028.31427.000
M30x3.53.56H26.21126.77127.72728.00730.00030.78526.500
M30x336H26.75227.25228.05128.31630.00030.69827.000
M30x2.52.56H27.29427.74428.37628.62630.00030.61127.500
M30x226H27.83528.21028.70128.92530.00030.51328.000
M30x1.51.56H28.37628.67629.02629.22630.00030.41628.500
M30x116H28.91729.15329.35029.52030.00030.31429.000
M30x0.750.756H29.18829.37829.51329.66330.00030.25829.250
M32x226H29.83530.21030.70130.92532.00032.51330.000
M32x1.51.56H30.37630.67631.02631.22632.00032.41730.500
M33x3.53.56H29.21129.77130.72731.00733.00033.78529.500
M33x336H29.75230.25231.05131.31633.00033.69830.000
M33x226H30.83531.21031.70131.92533.00033.51331.000
M33x1.51.56H31.37631.67632.02632.22633.00033.41731.500
M33x116H31.91732.15332.35032.52033.00033.31432.000
M33x0.750.756H32.18832.37832.51332.66333.00033.25832.250
M35x1.51.56H33.37633.67634.02634.22635.00035.41633.500
M36x446H31.67032.27033.40233.70236.00036.87732.000
M36x336H32.75233.25234.05134.31636.00036.69833.000
M36x226H33.83534.21034.70134.92536.00036.51334.000
M36x1.51.56H34.37634.67635.02635.22636.00036.41734.500
M36x116H34.91735.15335.35035.52036.00036.31435.000
M38x1.51.56H36.37636.67637.02637.22638.00038.41736.500
M39x446H34.67035.27036.40236.70239.00039.87735.000
M39x336H35.75236.25237.05137.31639.00039.69836.000
M39x226H36.83537.21037.70137.92539.00039.51337.000
M39x1.51.56H37.37637.67638.02638.22639.00039.41737.500
M39x116H37.91738.15338.35038.52039.00039.31438.000
M40x336H36.75237.25238.05138.31640.00040.69837.000
M40x2.52.56H37.29437.74438.37638.62640.00040.61137.500
M40x226H37.83538.21038.70138.92540.00040.51338.000
M40x1.51.56H38.37638.67639.02639.22640.00040.41638.500
M42x4.54.56H37.12937.79939.07739.39242.00042.96537.500
M42x446H37.67038.27039.40239.70242.00042.87738.000
M42x336H38.75239.25240.05140.31642.00042.69839.000
M42x226H39.83540.21040.70140.92542.00042.51340.000
M42x1.51.56H40.37640.67641.02641.22642.00042.41740.500
M42x116H40.91741.15341.35041.52042.00042.31441.000
M45x4.54.56H40.12940.79942.07742.39245.00045.96540.500
M45x446H40.67041.27042.40242.70245.00045.87741.000
M45x336H41.75242.25243.05143.31645.00045.69842.000
M45x226H42.83543.21043.70143.92545.00045.51343.000
M45x1.51.56H43.37643.67644.02644.22645.00045.41643.500
M45x116H43.91744.15344.35044.52045.00045.31444.000
M48x556H42.58743.29744.75245.08748.00049.05743.000
M48x446H43.67044.27045.40245.71748.00048.89244.000
M48x336H44.75245.25246.05146.33148.00048.71345.000
M48x226H45.83546.21046.70146.93748.00048.52546.000
M48x1.51.56H46.37646.67647.02647.23848.00048.42946.500
M50x446H45.67046.27047.40247.71750.00050.89246.000
M50x336H46.75247.25248.05148.33150.00050.71347.000
M50x226H47.83548.21048.70148.93750.00050.52548.000
M50x1.51.56H48.37648.67649.02649.23850.00050.42848.500
M52x556H46.58747.29748.75249.06752.00053.03747.000
M52x446H47.67048.27049.40249.71752.00052.89248.000
M52x336H48.75249.25250.05150.33152.00052.71349.000
M52x226H49.83550.21050.70150.93752.00052.52550.000
M52x1.51.56H50.37650.67651.02651.23852.00052.42950.500
M55x446H50.67051.27052.40252.71755.00055.89251.000
M55x336H51.75252.25253.05153.33155.00055.71352.000
M55x226H52.83553.21053.70153.93755.00055.52553.000
M55x1.51.56H53.37653.67654.02654.23855.00055.42853.500
M56x6.56.56H48.96449.81451.77852.17856.00057.33849.500
M56x5.55.56H50.04650.79652.42852.78356.00057.14950.500
M56x446H51.67052.27053.40253.71756.00056.89252.000
M56x336H52.75253.25254.05154.33156.00056.71353.000
M56x226H53.83554.21054.70154.93756.00056.52554.000
M56x1.51.56H54.37654.67655.02655.23856.00056.42954.500
M56x116H54.91755.15355.35055.54056.00056.33455.000
M58x446H53.67054.27055.40255.71758.00058.89254.000
M58x336H54.75255.25256.05156.33158.00058.71355.000
M58x226H55.83556.21056.70156.93758.00058.52556.000
M58x1.51.56H56.37656.67657.02657.23858.00058.42956.500
M60x5.55.56H54.04654.79656.42856.78360.00061.14954.500
M60x446H55.67056.27057.40257.71760.00060.89256.000
M60x336H56.75257.25258.05158.33160.00060.71357.000
M60x226H57.83558.21058.70158.93760.00060.52558.000
M60x1.51.56H58.37658.67659.02659.23860.00060.42858.500
M60x116H58.91759.15359.35059.54060.00060.33459.000
M62x446H57.67058.27059.40259.71762.00062.89258.000
M62x336H58.75259.25260.05160.33162.00062.71359.000
M62x226H59.83560.21060.70160.93762.00062.52560.000
M62x1.51.56H60.37660.67661.02661.23862.00062.42960.500
M63x1.51.56H61.37661.67662.02662.23863.00063.42961.500
M64x666H57.50558.30560.10360.47864.00065.24158.000
M64x5.55.56H58.04658.79660.42860.78364.00065.14958.500
M64x446H59.67060.27061.40261.71764.00064.89260.000
M64x336H60.75261.25262.05162.33164.00064.71361.000
M64x226H61.83562.21062.70162.93764.00064.52562.000
M64x1.51.56H62.37662.67663.02663.23864.00064.42962.500
M64x116H62.91763.15363.35063.54064.00064.33463.000
M65x446H60.67061.27062.40262.71765.00065.89261.000
M65x336H61.75262.25263.05163.33165.00065.71362.000
M65x226H62.83563.21063.70163.93765.00065.52563.000
M65x1.51.56H63.37663.67664.02664.23865.00065.42863.500
M68x666H61.50562.30564.10364.47868.00069.24162.000
M68x446H63.67064.27065.40265.71768.00068.89264.000
M68x336H64.75265.25266.05166.33168.00068.71365.000
M68x226H65.83566.21066.70166.93768.00068.52566.000
M68x1.51.56H66.37666.67667.02667.23868.00068.42966.500
M68x116H66.91767.15367.35067.54068.00068.33467.000
M70x666H63.50564.30566.10366.47870.00071.24164.000
M70x446H65.67066.27067.40267.71770.00070.89266.000
M70x336H66.75267.25268.05168.33170.00070.71367.000
M70x226H67.83568.21068.70168.93770.00070.52568.000
M70x1.51.56H68.37668.67669.02669.23870.00070.42868.500
M72x666H65.50566.30568.10368.47872.00073.24166.000
M72x446H67.67068.27069.40269.71772.00072.89268.000
M72x336H68.75269.25270.05170.33172.00072.71369.000
M72x226H69.83570.21070.70170.93772.00072.52570.000
M72x1.51.56H70.37670.67671.02671.23872.00072.42970.500
M72x116H70.91771.15371.35071.54072.00072.33471.000
M75x666H68.50569.30571.10371.47875.00076.24169.000
M75x446H70.67071.27072.40272.71775.00075.89271.000
M75x336H71.75272.25273.05173.33175.00075.71372.000
M75x226H72.83573.21073.70173.93775.00075.52573.000
M75x1.51.56H73.37673.67674.02674.23875.00075.42873.500
M76x666H69.50570.30572.10372.47876.00077.24170.000
M76x446H71.67072.27073.40273.71776.00076.89272.000
M76x336H72.75273.25274.05174.33176.00076.71373.000
M76x226H73.83574.21074.70174.93776.00076.52574.000
M76x1.51.56H74.37674.67675.02675.23876.00076.42974.500
M76x116H74.91775.15375.35075.54076.00076.33475.000
M78x226H75.83576.21076.70176.93778.00078.52576.000
M80x666H73.50574.30576.10376.47880.00081.24174.000
M80x446H75.67076.27077.40277.71780.00080.89276.000
M80x336H76.75277.25278.05178.33180.00080.71377.000
M80x226H77.83578.21078.70178.93780.00080.52578.000
M80x1.51.56H78.37678.67679.02679.23880.00080.42878.500
M80x116H78.91779.15379.35079.54080.00080.33479.000
M82x226H79.83580.21080.70180.93782.00082.52580.000
M85x666H78.50579.30581.10381.47885.00086.24179.000
M85x446H80.67081.27082.40282.71785.00085.89281.000
M85x336H81.75282.25283.05183.33185.00085.71382.000
M85x226H82.83583.21083.70183.93785.00085.52583.000
M85x1.51.56H83.37683.67684.02684.23885.00085.42983.500
M90x666H83.50584.30586.10386.47890.00091.24184.000
M90x446H85.67086.27087.40287.71790.00090.89286.000
M90x336H86.75287.25288.05188.33190.00090.71387.000
M90x226H87.83588.21088.70188.93790.00090.52588.000
M90x1.51.56H88.37688.67689.02689.23890.00090.42988.500
M95x666H88.50589.30591.10391.50395.00096.26689.000
M95x446H90.67091.27092.40292.73795.00095.91291.000
M95x336H91.75292.25293.05193.35195.00095.73392.000
M95x226H92.83593.21093.70193.95195.00095.53993.000
M95x1.51.56H93.37693.67694.02694.26295.00095.45393.500
M100x666H93.50594.30596.10396.503100.000101.26694.000
M100x446H95.67096.27097.40297.737100.000100.91296.000
M100x336H96.75297.25298.05198.351100.000100.73397.000
M100x226H97.83598.21098.70198.951100.000100.53998.000
M100x1.51.56H98.37698.67699.02699.262100.000100.45398.500
M105x666H98.50599.305101.103101.503105.000106.26699.000
M105x446H100.670101.270102.402102.737105.000105.912101.000
M105x336H101.752102.252103.051103.351105.000105.733102.000
M105x226H102.835103.210103.701103.951105.000105.539103.000
M105x1.51.56H103.376103.676104.026104.262105.000105.453103.500
M110x666H103.505104.305106.103106.503110.000111.266104.000
M110x446H105.670106.270107.402107.737110.000110.912106.000
M110x336H106.752107.252108.051108.351110.000110.733107.000
M110x226H107.835108.210108.701108.951110.000110.539108.000
M110x1.51.56H108.376108.676109.026109.262110.000110.453108.500
M115x666H108.505109.305111.103111.503115.000116.266109.000
M115x446H110.670111.270112.402112.737115.000115.912111.000
M115x336H111.752112.252113.051113.351115.000115.733112.000
M115x226H112.835113.210113.701113.951115.000115.539113.000
M115x1.51.56H113.376113.676114.026114.262115.000115.453113.500
M120x666H113.505114.305116.103116.503120.000121.266114.000
M120x446H115.670116.270117.402117.737120.000120.912116.000
M120x336H116.752117.252118.051118.351120.000120.733117.000
M120x226H117.835118.210118.701118.951120.000120.539118.000
M120x1.51.56H118.376118.676119.026119.262120.000120.453118.500
M125x886H116.340117.340119.804120.254125.000126.605117.000
M125x666H118.505119.305121.103121.503125.000126.266119.000
M125x446H120.670121.270122.402122.737125.000125.912121.000
M125x336H121.752122.252123.051123.351125.000125.733122.000
M125x226H122.835123.210123.701123.951125.000125.539123.000
M125x1.51.56H123.376123.676124.026124.262125.000125.453123.500
M130x886H121.340122.340124.804125.254130.000131.605122.000
M130x666H123.505124.305126.103126.503130.000131.266124.000
M130x446H125.670126.270127.402127.737130.000130.912126.000
M130x336H126.752127.252128.051128.351130.000130.733127.000
M130x226H127.835128.210128.701128.951130.000130.539128.000
M130x1.51.56H128.376128.676129.026129.262130.000130.453128.500
M135x666H128.505129.305131.103131.503135.000136.266129.000
M135x446H130.670131.270132.402132.737135.000135.912131.000
M135x336H131.752132.252133.051133.351135.000135.733132.000
M135x226H132.835133.210133.701133.951135.000135.539133.000
M135x1.51.56H133.376133.676134.026134.262135.000135.453133.500
M140x886H131.340132.340134.804135.254140.000141.605132.000
M140x666H133.505134.305136.103136.503140.000141.266134.000
M140x446H135.670136.270137.402137.737140.000140.912136.000
M140x336H136.752137.252138.051138.351140.000140.733137.000
M140x226H137.835138.210138.701138.951140.000140.539138.000
M140x1.51.56H138.376138.676139.026139.262140.000140.453138.500
M145x666H138.505139.305141.103141.503145.000146.266139.000
M145x446H140.670141.270142.402142.737145.000145.912141.000
M145x336H141.752142.252143.051143.351145.000145.733142.000
M145x226H142.835143.210143.701143.951145.000145.539143.000
M145x1.51.56H143.376143.676144.026144.262145.000145.453143.500
M150x886H141.340142.340144.804145.254150.000151.605142.000
M150x666H143.505144.305146.103146.503150.000151.266144.000
M150x446H145.670146.270147.402147.737150.000150.912146.000
M150x336H146.752147.252148.051148.351150.000150.733147.000
M150x226H147.835148.210148.701148.951150.000150.539148.000
M150x1.51.56H148.376148.676149.026149.262150.000150.453148.500

References

  • ISO 68:1973 ISO general purpose screw threads - Basic profile
  • ISO 261:1973 ISO general purpose metric screw threads - General plan
  • ISO 262:1973 ISO general purpose metric screw threads - Selected sizes for screws, bolts and nuts
  • ISO 724:1993 ISO general-purpose metric screw threads - Basic dimensions
  • ISO 965-1:1980 ISO general purpose metric screw threads - Tolerances - Part 1: Principles and basic data
  • ISO 965-2:1980 ISO general purpose metric screw threads - Tolerances - Part 2: Limits of sizes for general purpose bolt and nut threads - Medium quality
  • ISO 965-3:1980 ISO general purpose metric screw threads - Tolerances - Part 3: Deviations for constructional threads
  • ISO 1502:1996 ISO general-purpose metric screw threads - Gauges and gauging

Please note - do not rely on the above information without checking the source material in case any errors have crept in.