How to use the Reptile Feeder Insect Size Selector
Choosing a size is the step that stalls most people at the feeder-insect shelf. Too large and the animal struggles to swallow or brings it back up; too small and you are buying volume instead of a meal. Measure your reptile's head width yourself, add the ratio printed in the care source you follow and the margin you want to allow, and this selector returns the prey length to look for in inches.
The arithmetic is plain: head width multiplied by your ratio gives the target length, and the tolerance is applied either side of it to make a range. The formula used is printed with the result, so if you swap in a ratio from a different source you can see exactly where the number moved. The difference against head width is shown as well, which makes it obvious when a ratio from a general guide is far too large for the animal in front of you.
One limit matters. As of October 2026, no veterinary body such as AAHA or WSAVA, and no recognized keeping authority, publishes a feeder-insect size table for reptiles. Species run into the hundreds and individuals within a species differ widely, so this tool asks you to pick no species and offers no default ratio. The ratio must come from a source you trust or from your veterinarian. This tool is for reference only and does not replace veterinary care. Contact your veterinarian right away if you notice symptoms or suspect a problem.
Frequently asked questions
The tool deliberately suggests none, because no recognized size table exists. Use the ratio given in the care source for your species or by your veterinarian, and where the source gives a range, start at the lower end.
Look down from above and measure across the widest part of the head. Using the same point every time is what lets you judge consistently when the animal has grown into a larger feeder size.
No. Counts and feeding frequency are outside this tool, which deals only with the length of a single feeder. How much to offer per day depends on weight, age and feeder type, so discuss that with your veterinarian.