Uncertainty budgets can be used for a variety of situations, e.g. reporting the total uncertainty, calculating tolerance limits or method optimisation. In this paper it is demonstrated how the use of uncertainty budgets can help in reducing the total uncertainty of an analytical method, i.e. method optimisation. In this example it has been possible to reduce the total uncertainty of a concentration determination of hydrogen peroxide (by titration) from 2.7 × 10⁻² M to 3.93 × 10⁻³ M (or to about a 1/7) by changing the traceability chain and working with more pure reagents.