Unconfined liquid spill depths were measured for two liquid fuels and three non-flammable liquids atop a smooth concrete pad. Unconfined liquid spill thicknesses were found to be less than 0.1 cm in all fuels and liquids similar to fuels. Spill fires were conducted with volumes ranging from 0.2 ml to 450 ml for gasoline and denatured alcohol. Average burning rates for both unconfined liquid fuel spill fires increased linearly with increasing volume spilled. A liquid spill thickness model was developed and compared to experimental data. Comparisons showed good predictions for half of the liquids used. In addition, a liquid spill fire burning rate model was also developed and checked with experimental data. This model provided good qualitative results, however further development is still needed.