Our Sources & Methodology

Last updated: September 26, 2026 · Reviewed against sources listed below

Every number on HerpMath comes from a source you can check. This page lists those sources, explains how we rank them, and describes exactly how each calculator works.

How we choose sources

1. Veterinary bodies and manuals, such as the Association of Reptile and Amphibian Veterinarians (ARAV) and the Merck Veterinary Manual.
2. University veterinary schools and veterinary hospitals, such as VCA Animal Hospitals.
3. Peer-reviewed research on reptile nutrition and growth.
4. Experienced breeders and keeper guides, used only to fill gaps and always cross-checked against the sources above.

We also use two supplementary kinds of source. General reference works such as Wikipedia help us find the underlying studies. Specialist manufacturers and suppliers publish technical data: measured UVB output at different distances, feeder rodent weights, and mixing ratios printed on powdered diet labels. We use that data only for those specific numbers, never for animal care advice.

When sources disagree, we use the range they have in common and show it as a range, for example “10 to 15% of body weight,” rather than a single exact number.

Source list

Veterinary and animal-welfare organizations, and veterinary manuals

• Association of Reptile and Amphibian Veterinarians (ARAV)
• Merck Veterinary Manual — Reptiles (Exotic and Laboratory Animals)
• Merck Veterinary Manual — Reptiles (Pet Owner Version)
• Merck Veterinary Manual — Management and Husbandry of Reptiles
• RSPCA — How to Care for a Corn Snake
• Smithsonian’s National Zoo — Northern Blue-tongued Skink

Veterinary hospitals and clinical resources

• VCA Animal Hospitals — Bearded Dragons: Feeding
• VCA Animal Hospitals — Bearded Dragons: Owning
• VCA Animal Hospitals — Bearded Dragons: Housing
• VCA Animal Hospitals — Leopard Geckos: Care
• VCA Animal Hospitals — Snakes: Feeding
• VCA Animal Hospitals — Snakes: Owning
• VCA Animal Hospitals — Snakes: Housing
• LafeberVet — veterinary resources for exotic animals
• VCA Animal Hospitals — Bearded Dragons: Diseases
• LafeberVet — Nutritional Support in Reptiles
• Wildwood Veterinary Hospital — Ball Python Care
• VCA Animal Hospitals — Leopard Geckos: Care and Feeding
• PetMD — Corn Snake Care Sheet (written by a veterinarian)
• Tree of Life Exotic Pet Medical Center — Western Hognose Snake Care
• PetMD — Crested Gecko Care Sheet (written and reviewed by veterinarians)
• Long Island Bird & Exotics Veterinary Clinic — Crested Gecko Care Guide
• LafeberVet — Basic Information Sheet: Northern Blue-Tongued Skink
• Long Island Bird & Exotics Veterinary Clinic — Blue-Tongued Skink Care Guide
• Animal Diversity Web (University of Michigan) — Python regius

Peer-reviewed literature

• Endocrine aspects of ovary growth and gestation in the Argentinian cockroach, Blaptica dubia — Invertebrate Reproduction & Development (2013)
• Baines F. et al. (2016). How much UV-B does my reptile need? The UV-Tool, a guide to the selection of UV lighting for reptiles and amphibians in captivity. Journal of Zoo and Aquarium Research 4(1): 42–63
• Aubret F., Bonnet X., Harris M., Maumelat S. (2005). Sex differences in body size and ectoparasite load in the ball python, Python regius. Journal of Herpetology 39(2): 315–320

Experienced keepers (supplementary, always cross-checked)

• ReptiFiles — Bearded Dragon Care Guide
• ReptiFiles — Bearded Dragon Food
• ReptiFiles — Leopard Gecko Care Guide
• ReptiFiles — Leopard Gecko Feeding
• ReptiFiles — Ball Python Care Guide
• ReptiFiles — Ball Python Feeding
• ReptiFiles — Corn Snake Care Guide
• ReptiFiles — Crested Gecko Care Guide
• ReptiFiles — Bearded Dragon Terrarium Size
• ReptiFiles — Bearded Dragon Temperatures & UVB
• ReptiFiles — Leopard Gecko Terrarium Decorations
• ReptiFiles — Leopard Gecko Temperatures & Humidity
• ReptiFiles — Ball Python Terrarium Decorations
• ReptiFiles — Ball Python Humidity & Temperatures
• ReptiFiles — Leopard Gecko Terrarium Size
• ReptiFiles — Ball Python Terrarium Size & Lighting
• Reptiles Magazine — The Vet Report: Reptile Vomiting and Regurgitation
• DubiaRoaches.com — Breeding Dubia Roaches
• Dubia Roach Depot — Breeding Dubia Roaches: A Comprehensive Guide
• ReptiFiles — Corn Snake Food
• ReptiFiles — Corn Snake Temperatures & Humidity
• ReptiFiles — Corn Snake Terrarium Size
• ReptiFiles — Corn Snake Substrate
• Cornsnakes.com forum — Length, weight and age data from keepers
• ReptiFiles — Hognose Snake Care Guide
• ReptiFiles — Hognose Snake Temperatures, Humidity & Lighting
• ReptiFiles — Hognose Snake Enclosure Size
• ReptiFiles — Hognose Substrate Options
• ReptiFiles — What Do Hognose Snakes Eat?
• Reptiles Magazine — Western Hognose Snake Care Sheet
• ReptiFiles — Crested Gecko Temperatures & Humidity
• ReptiFiles — Crested Gecko Terrarium Size & Cohabitation
• ReptiFiles — Crested Gecko Food
• Pangea Reptile — Crested Gecko Care
• Moon Valley Reptiles — Crested Gecko Growth Rates
• ReptiFiles — Blue Tongue Skink Care Guide
• ReptiFiles — Blue Tongue Skink Food & Feeding
• ReptiFiles — Blue Tongue Skink Temperatures, UVB & Humidity
• ReptiFiles — Blue Tongue Skink Enclosure Size
• ReptiFiles — Blue Tongue Skink Substrate
• BlueTongueSkinks.org forum — Growth chart from keepers

General reference works (supplementary)

• Wikipedia — Blaptica dubia
• Wikipedia — Central bearded dragon
• Wikipedia — Common leopard gecko
• Wikipedia — Ball python
• Wikipedia — Corn snake
• Wikipedia — Western hognose snake
• Wikipedia — Crested gecko

Specialist manufacturers and suppliers (label and technical data only)

• Arcadia Reptile — ShadeDweller UVB lamps (low-output UVB for crepuscular species)
• Arcadia Reptile — Species Lighting Guide
• Exo Terra — Comprehensive UV Index Table
• Zoo Med — PowerSun UV lamp instructions (Ferguson zone UV index table)
• RodentPro — Guide to Frozen Feeder Mouse Sizes
• RodentPro — Frozen Rats (sizes by weight)
• Perfect Prey — Frozen Mice (sizes by weight)
• Pangea Reptile — Gecko Diet with Insects (label mixing instructions)
• Pangea Reptile — Growth & Breeding Formula (label mixing instructions)
• Repashy Ventures — Crested Gecko MRP (label mixing instructions)

How each tool works

Snake Feeding Calculator

Prey weight = snake weight × a percentage set by life stage (10–15% for growing snakes, 5–10% for adults). Life stage is chosen from weight unless you pick one. Body condition adjusts the percentage and the feeding interval. The prey weight range is then matched to typical feeder rodent weights.

Lizard Insect Feeding Calculator

Life stage is chosen from age in months. Each stage has a number of insects per feeding (for crickets) and feedings per week. Other feeders are converted with a count factor. Weekly total = per feeding × feedings per week × number of animals. Omnivores such as blue tongue skinks are fed by portion instead: the tool shows the portion size, meals per week and the mix of protein, greens and fruit for the age you enter.

Calcium & Vitamin Schedule Generator

Each species, life stage and UVB setup has a weekly number of calcium-with-D3 and multivitamin dustings. These are spread evenly across your feeding days; remaining feedings get plain calcium where the species needs it.

Reptile Age & Growth Estimator

Each species has a typical length and weight range for each age. Ranges between listed ages are filled in on a straight line. The estimated age is every month whose normal range includes your measurement. If you enter a known age, your measurement is compared with the normal range for that age.

Reptile Enclosure Size Calculator

Each species has a minimum and a recommended size for one adult. For an unusually long animal, each dimension is raised to its total length times a set factor, rounded up to the next 6 inches. The smallest common tank that meets the minimum is then shown. The converter uses 231 cubic inches per US gallon.

Reptile Temperature & Humidity Checker

Each reading is compared with the species range. Readings within 2°F (or 5% humidity) outside the range are marked slightly off; anything further is marked too high or too low, with a suggested fix.

Dubia Roach Colony Calculator

Weekly roach use comes from the insect feeding amounts for each reptile. Adult females needed = weekly use ÷ the number of feeder-sized roaches one female can supply each week. Males are added at one per three to five females.

Crested Gecko Diet Mix Calculator

Water = powder amount × the water ratio from the maker’s label (2 parts water for most diets, 2.5 for Pangea Growth & Breeding), by volume. Teaspoons and tablespoons are converted to milliliters. Feeding frequency comes from the gecko’s age, and the batch count uses the fridge life stated on the label.

Verification status

Each data file has a verification record listing its sources, the person who checked it and the date. Values marked “pending” are drafted from the listed sources and are awaiting a final check.

Photo credits

Species photos come from open photo libraries (Wikimedia Commons and iNaturalist) and are in the public domain or released under CC0, so they may be used freely. We credit the photographers anyway.

• Ball Python: Queen Alphabet the ball python, Capen Hill Nature Sanctuary 2026-07-10.jpg by Peter Cooper Jr. (CC0)
• Corn Snake: Pantherophis guttatus.jpg by Koswac (Public domain)
• Hognose Snake: Western Hognose Snake (Heterodon nasicus). High resolution image. (614d8699-155d-451f-6761-d3f40052d1ff).JPG by NPS Photo (Public domain)
• Leopard Gecko: Eublepharis macularius 2009 G6.jpg by George Chernilevsky (Public domain)
• Crested Gecko: crested gecko, eyelash gecko, kronengecko by kheintzman (CC0)
• Bearded Dragon: Pogona vitticeps 2009 G3.jpg by George Chernilevsky (Public domain)
• Blue Tongue Skink: Bird, a northern blue-tongued skink eating dinner.jpg by Rabbott656 (CC0)

Updates and corrections

We review all data every quarter. This page was last reviewed on September 26, 2026. If you find an error, please contact us with your source.