Conversion widgets are easy and fast to use, I have one on my desktop and use it when I need more than an approximate idea. People wouldn't need it just to read about the plant and it would be there if they decided they wanted more exact info. I have approximate exchanges in my head, 1 inch is about 2.5 cm, 4 inches is 10cm, 6 miles is 10 km, a kilo is 2.2 lbs, I can remember those and get an approximation. For accuracy, you need a converter. I don't see that it makes sense to convert everything, just give folks an easy way to do it themselves.
