A caliper is $6, accurate, & easy to use.

Accu-Measure 3000 Buy @ amazon.com / Instruction Manual

How to Accurately Measure Body Fat Percentage Article / Video

A clinical study published in the Journal of Strength and Conditioning Research by the National Strength & Conditioning Association and independently funded by EAS showed that:

• Self-testing of % body fat with the Accu-Measure® was as accurate as results from multi-site measurements and calculations taken by an experienced clinical investigator using a Lange caliper.

• % body fat calculations with the Accu-Measure® were within 1.1 percentage points of underwater weighing results, the gold standard of body fat measurement.

You could buy some calipers. They are fairly cheap and are good for tracking change over time.

These are the cheap pair: http://www.amazon.com/Accu-Measure-Fitness-Personal-Caliper-Measurement/dp/B000G7YW74

And for a few more dollars, these seem like they would be more convenient: http://www.amazon.com/dp/B000NN9SDO/ref=wl_it_dp_o_pC_S_ttl?_encoding=UTF8&colid=31VY55A8AMG4Z&coliid=I2Y1Q0J7STB37J