  We outline a systematic approach to the determination of the Standard
Model-like Higgs boson total width and measurable coupling parameters in a
model-independent manner at the International Linear Collider (ILC) and
illustrate the complementarity for operating the ILC at $250$ GeV near the $Zh$
threshold and at $500$ GeV and $1$ TeV utilizing the $WW, ZZ$ fusion processes.
We perform detailed simulations for an important contributing channel to the
coupling determination and for invisible decays. Without model assumptions, and
combining the information for the coupling ratios from the LHC, the total width
can be determined to an accuracy of about $6%$, and the couplings for the
observable channels can be measured to the $(3-5)%$ level at 250 GeV, reaching
$(1-3)%$ level including the 500 GeV results, with further improvements
possible with a $1$ TeV run. The best precision for the branching fraction
measurement of the Higgs to invisible modes can be reached at $0.5-0.7%$ around
the $Zh$ threshold. Further studies from $ZZ$ fusion at higher energies may
provide significant improvement for the measurements. With modest theory
assumptions, the width and coupling determinations can be further improved to
the percent or sub-percent level.
