A simple calculational method is developed that can quickly and accurately estimate total control rod worth for a class of reactors possessing fuel/control channel symmetry throughout its core. The movable, nonfissionable, poisoned control channel has identical neutron absorption and scattering properties and geometry similar to the fuel channels. Hexagonal lattices employed in fast breeder and graphite-moderated thermal reactors possess the necessary fuel/control lattice symmetry with spectrally innocuous coolants for both channels (sodium or helium both for fast and thermal systems) required to apply the method. The number of fuel and control channels is the parameter determining control worth and is tantamount to estimating by inspection. It is applied to eight fast sodium-cooled reactors and four thermal-, sodium-, or helium-cooled, graphite-moderated reactors. The Δk/k estimated worths are generally better than ±20% plant values.