SectionHobbies & Interests
Tools22 calculators
Last reviewed28 July 2026
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24 hobby tools, grouped by craft

Hobbies run on two questions that are surprisingly hard to answer: how much material will this take, and how long will it actually take me. These sections group the tools by craft so nothing gets buried in a single long list.

Every calculator in this section carries a full explanation: what it works out, the method, a worked example, the mistakes people make, and where a rule of thumb is weaker than its popularity suggests. Pages covering resins, solvents and animal welfare set out the safety and legal position rather than leaving it implied. Knitting, crochet and stitching tools now have a section of their own.

If you are not sure where to begin, these tools answer the questions readers ask most often in this section.

Photography Exposure HelperHow shutter, aperture and ISO trade against one another. Telescope Magnification CalculatorWhat an eyepiece will actually give you, and its useful limit. Collection Value CalculatorWhat a collection would really fetch, once condition and the selling route are accounted for. Scale Model Paint CalculatorWorks out paint volume before a build stalls halfway. 3D Printer Filament CalculatorTurns a print into a material cost you can actually quote. Aquarium Volume CalculatorThe number every other aquarium decision depends on.

Scale models and miniatures 9 tools

Build time, paint stock, display space and the scale conversions that modelling depends on.

Model Kit Build Time EstimatorEstimate build time from parts, complexity and finish level. Advanced Model Kit Stash CalculatorEstimate stash value, insurance value, build backlog and projected completion date. Scale Model Paint CalculatorEstimate paint needed for a model kit or miniature project. Model Paint Stock CheckerPaste a model paint list and your current stock to see what you still need to buy. Hobby Paint Coverage CalculatorEstimate paint required. Scale Model Display Cabinet PlannerEstimate display cabinet shelf size for a scale model collection. Model Railway Gradient CalculatorCalculate model railway gradient. Scale Speed CalculatorConvert model speed to scale speed. LEGO Brick EstimatorEstimate bricks for a build volume.

Making, casting and printing 3 tools

Material quantities and mix ratios where getting the proportion wrong wastes the whole batch.

3D Printer Filament CalculatorEstimate filament cost. Resin Mixing CalculatorCalculate resin and hardener quantities. Epoxy Mixing CalculatorCalculate epoxy component A quantity.

Photography and astronomy 4 tools

Exposure relationships, image storage and telescope magnification.

Photography Exposure HelperCompare shutter speed, aperture and ISO changes. Photography Storage CalculatorPlan working storage, archive growth and backup copies. Camera Memory Card EstimatorEstimate photo and video capacity on a memory card. Telescope Magnification CalculatorCalculate telescope magnification.

Collections and their value 1 tool

What a collection is worth depends less on what is in it than on its condition, whether it is complete, and how you sell it. One calculator now covers board games, vinyl, books, comics, video games, cards, discs and model kits.

Collection Value CalculatorWhat a collection would really fetch, after condition, completeness, selling route and fees.

Aquariums, games and reading 4 tools

Tank volume and stocking, puzzle time and how long a book will realistically take.

Aquarium Volume CalculatorCalculate aquarium volume. Aquarium Stocking GuideEstimate a conservative fish-length allowance. Jigsaw Completion EstimatorEstimate completion time. Book Reading Time PlannerPlan how long a book will take to finish based on pages, reading speed and daily reading time. Bicycle Gear Ratio CalculatorTurns chainring and sprocket teeth into gear inches, development and speed.

Common questions

Are the collection valuations reliable enough for insurance?

They are a starting figure, not a valuation. The tools total up the values you supply, so the output is only as good as your per-item estimates. For anything genuinely valuable — first editions, rare pressings, out-of-print games — get a specialist valuation, and check what your home insurance treats as a single-article limit.

Do the paint and resin tools account for waste?

Yes, through an adjustable allowance. Airbrushing wastes considerably more than brush painting, and two-part resin has to be mixed in whole batches, so a small overage is normal. Mix ratios for resin and epoxy are given by the tool but should always be checked against the specific product — they vary between manufacturers and getting them wrong prevents curing entirely.

How reliable are the build and project time estimates?

Directionally useful, individually unreliable. They are built from typical rates and scale sensibly — a kit with twice the parts really does take roughly twice as long — but personal speed varies enormously with experience and how much detailing you do. Use them to compare projects rather than to promise a finish date.

Is anything about my collection or projects stored?

No. Item values, project details and measurements are processed in your browser and never transmitted or retained as calculator records.

Questions rarely sit inside a single subject. These sections cover the calculations most often needed alongside hobby projects.

Yarn & NeedlecraftKnitting, crochet, cross stitch and embroidery, now in their own section. TechnologyPhotography storage, memory cards and archive planning. Home & DIYWorkshop space, shelving, display and finishing materials. Finance & BudgetingProject costs, cost per use and collection value. Everyday LifeTime value, competition odds and everyday leisure decisions. GardeningOutdoor projects for when the workshop gets too warm. All toolsEvery calculator on the site in one browsable list.
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