I bought a paraffin bath (good for aching parts) and want to know how
much it costs to run, let's say, per hour +-.

Called the local elec co, but lady said she couldn't give a figure by
the hour, only in KWH. Also depends on whether I want to keep it on
all the time, or shut on & off.

But my decision (on or on&off) depends on the relative costs.

Chicken - egg?

Anybody have an approximation?

Appliance is 120 volt, 100 watt. It has a setting to heat up the
paraffin, another setting to maintain operating temp., and another
setting for "solid" (what's the point of that one?)

TIA

Aspasia