You can always submit your measurement after placing the order. For now, just select Customize with Made to Measure, click Add to Shopping Bag and complete order. Later on go to Account section, visit My Orders page and submit your latest measurement.
If your bare chest size measurement is 40 inches, you should select size 40 only from the product page. The "Top Chest" attribute in the size chart refers to the garment's chest size. It is inclusive of the required 3 to 4 inches loosening, to ensure the right fit.
If your bare chest measurement falls between 2 sizes i.e 37 inches, you should select size 38.
https://www.utsavfashion.com/product/plain-art-silk-nehru-jacket-in-dark-green-mhg510553115Plain Art Silk Nehru Jacket in Dark Greenhttps://medias.utsavfashion.com/media/catalog/product/cache/1/small_image/295x/040ec09b1e35df139433887a97daa66f/m/h/mhg510.jpg6075USDInStock/men/men/plus/men/festive/men/art silk/men/green/men/nehru jackets/men/plain/men/traditionalPlain Art Silk Nehru Jacket in Dark Green <ul><li> Readymade Art Silk Nehru Jacket in Dark Green</li><li> Enhanced with Moulded Buttons and Pockets</li><li> Do note: Kurta, Pajama and Footwear shown in the image are for presentation purposes only. Half to one inch may vary in measurement. (Slight variation in actual color vs. image is possible).</li></ul>USDtype_new:Nehru Jacketscolorfam:Greenfabric:Art SilkGreenArt SilkNehru Jackets11%-20%MenReady to Ship, Within 2 days, Within 7 days, Within 10 days, Within 15 days, More than 15 DaysReadymadeFestiveMenswearPlain, Traditional32, 34, 36, 40, 4244