36 home and DIY tools, grouped by job
Most DIY mistakes are quantity mistakes: two tins short, one pack of tiles too many, a post hole that is not deep enough. These sections follow the order a project usually runs in — prepare the surface, get the materials right, fix things safely, then fit out the room.
Every calculator in this section now carries a full explanation: what it works out, the method, a worked example you can reproduce, the mistakes people make, and where the job crosses into building regulations or professional territory. Where safety matters — cement, silica dust, buried services, working at height, floor loading — the page says so and links to HSE guidance.
Start here
If you are not sure where to begin, these tools answer the questions readers ask most often in this section.
Paint, wallpaper and decorating 7 tools
Surface areas, coverage rates and drying times for the finishing work.
Concrete, masonry and groundwork 7 tools
Volumes, mix ratios and pack quantities for anything involving cement, brick or hardcore.
Structure, roofing and outdoor building 6 tools
Pitch, tile counts, timber runs, drainage and the planning rules that apply to garden buildings.
Fixings, tools and working safely 4 tools
Choosing the right bit and fixing for the material, and knowing when a job needs professional advice.
Storage, loft and living space 6 tools
Making better use of the space you already have, and clearing what you no longer need.
Fitting out a room 5 tools
Curtains, screens and heating sized to the room rather than to the box they came in.
Common questions
How much waste allowance should I add to a material order?
It depends on the material and the cutting involved. Around 10% is a reasonable default for tiles, wallpaper and timber; 5% is usually enough for bulk materials such as concrete or gravel where you can order a little over; and 15% or more is sensible for patterned tiles, diagonal layouts or anything with a repeat to match. Every tool here shows the waste allowance as an editable figure so you can set it for the job in front of you.
Why does the calculator disagree with the coverage on the tin?
Manufacturer coverage figures are measured on a smooth, sealed, previously painted surface under laboratory conditions. Bare plaster, textured wallpaper, masonry and anything porous will absorb noticeably more. Where a tool asks for a coverage rate it uses the figure you supply, so start with the tin and reduce it if the surface is absorbent or unsealed.
Are these calculators using UK building conventions?
Yes. Timber sizes, brick coursing, standard tin and roll sizes, skip capacities and permitted development guidance all follow UK practice, and quantities are given in metric with imperial conversions where they are still commonly used on site.
Do these tools replace Building Regulations or planning advice?
No. The garden building checker outlines general permitted development principles, and the floor loading tool flags when a load is worth checking, but neither is a substitute for your local authority or a structural engineer. Anything structural, electrical, gas-related or affecting a party wall needs a qualified professional and, usually, formal approval.
Is anything I type stored?
No. Every calculation runs locally in your browser. Room dimensions, budgets and material quantities are never sent to a server and are not kept as calculator records.
Which tool should I start with on a redecorating job?
The Room Paint Planner, because it establishes the wall areas that most of the other decorating tools also need. Once you have those measurements, the wallpaper, splashback and tile calculators become quick follow-ups.
Related subjects
Questions rarely sit inside a single subject. These sections cover the calculations most often needed alongside home and DIY projects.