Total Magnification Calculator

Total magnification is the objective times the eyepiece: a 40× objective with a 10× eyepiece gives 400×. Some stands add a third factor — a tube lens of 1.25× or 1.5×; multiply that in yourself, this calculator uses the two named lenses. Magnification is not resolution.

A compound microscope magnifies twice over. The objective forms an enlarged image inside the tube and the eyepiece enlarges that image again, so the two factors compound rather than add, and the total is their product. With the defaults, a 40× objective under a 10× eyepiece gives 400×, the working setting of almost every school microscope. Because the eyepiece is a fixed 10× on most stands, the entire range comes out of the turret: 4×, 10×, 40× and 100× against that eyepiece produce 40×, 100×, 400× and 1000×. The total is therefore a property of the current setting rather than of the instrument, and it changes with every click of the nosepiece. What the product does not record is which pair produced it. The objective decides what you are actually doing — finding the specimen, surveying tissue, working dry at high power or going into oil — so two pairings that reach the same total are not the same view. The limitation sits in the second field. This page multiplies exactly the two lenses you name, and some stands carry a third element between them, an intermediate or tube lens of 1.25× or 1.5×, printed on the body. There is deliberately no field for it: a default of 1 would be dead weight on the great majority of microscopes, and a silently built-in 1.25 would be plainly wrong on every stand without such a lens. Check your own and multiply it in.