A number of methods exists to fail rock in tension. In general the experimental results obtained by these methods differ, and it is not known how to quantitavely compare them other than by empiricism, even to obtain a value for tensile strength. Thus at present, these simple and very useful tests which measures strength indirectly have their values considered only as an index of strength. In this note a new approach is given which could enable a comparison of these results to be made and so enhance the usefulnes of these tests : it is based on the force at failure and the initial geometrical area of failure rather than upon the ratio of force and area, i.e. stress. For this purpose, published data on sandstones, marble and granite are used.