Hobby calculators
10 browser-based hobby calculators and utilities. Every formula runs locally - no upload, no sign-up, no tracking of the numbers you type.
All hobby tools
10 tools, each runs locally in your browser. Click any card to open it.
Carpet $2-8/ft² · Padding $0.30-0.80/ft² · Install $1-2/ft².
Cat Age in Human Years takes two timestamps or a base plus delta and returns the matching cat age in human years resul…
Cat Food Portion Calculator is a free pets calculator that gives you a deterministic answer for cat food portion quest…
Dog Age in Human Years takes two timestamps or a base plus delta and returns the matching dog age in human years resul…
Dog Food Portion Calculator is a free pets calculator that gives you a deterministic answer for dog food portion quest…
Knitting Yarn Calculator takes project parameters or constraints and returns the matching knitting yarn result. Runs e…
Pet Insurance Cost Calculator takes coverage, deductible, term, age and returns the matching pet insurance cost result…
SERP Snippet Preview is a free seo calculator that gives you a deterministic answer for serp snippet preview questions…
🎵 Metronome takes project parameters or constraints and returns the matching 🎵 metronome result. Runs entirely in yo…
AI book recommender that suggests what to read next based on your favorite books, genres, mood and length. Free, no si…
About hobby
Hobby calculators cover specialty interests that don't fit larger categories: dog and cat age conversion to human years, pet food daily caloric intake by weight and activity, knitting/crochet gauge and yardage, woodworking board-foot pricing, model-railroad scale conversion, and pet medication weight-based dosing for common species.
Use these for: converting a 7-year-old golden retriever to roughly 50 human years, computing daily kcal for a 25 lb dog at maintenance activity, estimating yardage for a sweater pattern at your gauge, pricing rough lumber by board foot, or scaling a HO model railroad layout (1:87) to real-world inches.
Sources: AAHA pet age guidance (better than the old 7-years rule), AAFCO pet food caloric standards, US woodworking board-foot trade standard. Pet medication tools are for screening; actual dosing belongs with a veterinarian.
Common use cases
Real scenarios where the hobby calculators in this category earn their keep.
Dog age in human years
AAHA approach: 15 years at age 1, 24 at age 2, then +5 per year for medium breeds. Large and giant breeds age faster; small breeds slower. The tool adjusts for breed size.
Cat age in human years
15 years at age 1, 24 at age 2, then +4 per year. Cats age more slowly than large dogs but still meaningfully faster than humans.
Pet food daily intake
Maintenance Energy Requirement (MER): 70 × weight(kg)^0.75 × activity multiplier (1.0 sedentary, 1.6 active intact adult, 2-3 active growing). The tool returns daily kcal and converts to cups of your specific brand.
Knitting yardage estimate
Yardage per sweater scales with size and fiber. A typical adult-medium pullover needs 1,000-1,400 yards of worsted-weight wool. The tool runs the math for your specific gauge and dimensions.
Board-foot pricing
1 board foot = 144 cubic inches of lumber (1×12×12). Price = volume × per-board-foot rate. Used for rough-sawn and hardwood lumber pricing.
Key terms
Glossary for the formulas and conventions these tools use.
- Human-year equivalent (dog)
- Better than 7-years rule. 15 at age 1, 24 at age 2, +5 per year for medium breeds. Large and giant breeds add faster.
- MER (Maintenance Energy Requirement)
- Daily kcal a healthy adult pet needs at rest plus normal activity. AAFCO formula: 70 × weight(kg)^0.75 × activity multiplier.
- Board foot
- 144 cubic inches of lumber (1 inch thick × 12 inches wide × 12 inches long). Standard pricing unit for hardwood and rough-sawn.
- Knitting gauge
- Stitches and rows per 4 inches (10 cm). Critical for sizing; a gauge error of even half a stitch per inch will shift sweater size by inches.
- WPI
- Wraps Per Inch. Yarn-thickness measurement when the ball band is missing. Fingering ~14 WPI, worsted ~9 WPI, bulky ~6 WPI.
- Scale (model trains)
- Ratio of model to real. N = 1:160, HO = 1:87, O = 1:48. Determines layout footprint for a given real-world length.
- Activity multiplier (pets)
- 1.0 indoor-only sedentary, 1.4 spayed/neutered adult, 1.6 active intact adult, 2.0-3.0 working/growing.
Frequently asked questions
Short answers to the most common hobby questions.