  We adduce the results of the condensate fraction calculation for liquid
helium-4. The method is derived from the first principles and involves minimum
assumptions. The only experimental quantity we need in our calculations is the
static structure factor which is easily measurable. We use the approximation in
which expressions contain one summation in the wave vector space (or one
integration it the radius vector space) in order to demonstrate the validity of
our method. The computed values of the condensate fraction lie within $8.8 \div
14%$ depending on the model potential for the short-range interaction. This
result agrees with recent experimental measurements and numerical estimations.
