A different dodgy app for every calculation
One ad-riddled app for voltage drop, another for gas rate, a third for BTUs. TradePlanr puts 48 proper trade calculators in the same app as your jobs and paperwork.
The trade calculators you actually use, in one app
Voltage drop, gas rate, radiator BTU, cable sizing, air con sizing — 30 calculators built around UK regs, working offline on site. Every one is also free to try in your browser at tradeplanr.com/calculators.
Free to start · No card · No download needed — works in your browser
🇬🇧 Built in the UK for UK tradesFree to start — no card requiredWorks offline on siteCard payments secured by Stripe
On iPhone, Android and any browser
Sound familiar?
BS 7671 maths on the back of an envelope
Voltage drop, max Zs, adiabatic checks — get it wrong and it's a failed inspection. Every electrical calculator is BS 7671-referenced with guidance notes.
No signal, no answers
Plant rooms, basements and new-builds are exactly where you need a calculator most. The whole toolbox works offline on site.
How TradePlanr does it
12 electrical calculators
Voltage drop to BS 7671, max Zs, Zs from Ze, R1+R2, adiabatic, cable sizing, power factor correction, ring continuity, max demand, Ohm's law, kW to amps and trunking fill.
8 gas and heating calculators
Gas rate from a timed meter test, gas pipe sizing, ventilation area, radiator BTU, expansion vessel, system volume, cylinder reheat and flow rate/ΔT.
Guidance you can stand behind
Calculators reference BS 7671 where it applies, with guidance notes and clear disclaimers — a sense-check, not a guess.
Free in your browser too
Every calculator is free to try on the web at tradeplanr.com/calculators — no app, no account. In the app, they work offline and live next to your jobs.
Need the full tour? See everything the TradePlanr app does.
See it in action
Real screens from the TradePlanr app — no stock photos, no mock-ups.
Common questions
Which calculators are included?
23 in total: 12 electrical (voltage drop to BS 7671, max Zs, Zs from Ze, R1+R2, adiabatic, cable sizing, power factor correction, ring continuity, max demand, Ohm's law, kW to amps, trunking fill), 8 gas and heating (gas rate, gas pipe sizing, ventilation area, radiator BTU, expansion vessel, system volume, cylinder reheat, flow rate/ΔT) and 3 general (energy cost, unit converter, markup and VAT).
Do the calculators work offline?
Yes — the toolbox in the app works with no signal at all, so plant rooms and basements aren't a problem.
Can I try the calculators without installing the app?
Yes — every calculator is free to use in any browser at tradeplanr.com/calculators. The app adds offline use and puts them alongside your jobs, quotes and certificates.
Try TradePlanr free today
Start free in your browser and set up your first job in minutes — no download needed.