Everyone in this category says they tested a dozen bird bath heaters. We have not tested any, and we say so. What we do instead: read the manufacturers’ own listings, compile the published specifications, compute what each unit costs to run for a winter at a cited electricity rate, and check the prices every day.
That is a smaller claim than a test lab and it is one you can check. Every wattage on this site links to the listing it came from. Every dollar figure comes from one formula, printed in full, that you can rerun with your own utility rate. Where a maker publishes no wattage — and four of the units here do not — we say that too, rather than estimating a number to fill the column.
Written by Scooter M., an enthusiast who is genuinely into this. No lab coat. The full method is published, which is more than anyone else in this niche does.