The Collaborative International Dictionary of English v.0.48:

Calculable \Cal"cu*la*ble\, a. [Cf. F. calculable.]
   That may be calculated or ascertained by calculation.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

50 Moby Thesaurus words for "calculable":
   anticipatable, appraisable, appreciable, assessable, computable,
   countable, dependable, determinable, divinable, estimable,
   faithful, faithworthy, fast, fathomable, firm, foreknowable,
   foreseeable, foretellable, gaugeable, improbable, invincible,
   measurable, mensurable, meterable, noticeable, numberable,
   numerable, perceptible, precognizable, predictable, probable,
   quantifiable, quantizable, reckonable, reliable, secure, solid,
   sound, stable, staunch, steadfast, steady, substantial, sure,
   surefire, trustworthy, trusty, unfailing, well-founded,
   well-grounded