Quote to certificate. All in one place.
Add the job. Ohmly builds the circuits, runs the checks and writes the paperwork.
Certificates, test results and quotes for UK electricians, written from the job.
Built for UK 230 V and 400 V installation work to BS 7671:2018+A4:2026. Android. Works with no signal.
Introducing Ohmly
You do the work. Ohmly does the paperwork.
Ohmly is the app for UK electricians that turns a few simple questions about a job into everything the job needs on paper: the circuits, the safety checks, the quote and the certificate.
Your paperwork, done as you work
Ohmly completes your paperwork automatically, as you do the job. No evenings lost to typing up, so you save time and money.
Every figure entered once
You never enter a figure more than once, so there is no more repetitive paperwork. Less time on admin means more time on paid work.
Grow with repeat business
Your customers keep paperwork with your brand and contact details on it, so you are the first call next time.
Answer a few questions. Ohmly does the rest.
Each stage feeds the next, so nothing is typed twice: your answers become the circuits, the circuits become the quote, and your test results become the certificate.
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Add the job
Pick the job type and answer a few simple questions.
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Circuits built
Every circuit drawn, with cable sizes, protection and RCDs chosen for you.
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Checks run
Bonding, earthing, AFDD, SPD, zones and Zs, against your design.
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Materials and quote
Every part listed for you; on Pro, priced at your rates and turned into the quote.
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Checklist and tests
Safe isolation, the checklist, then readings checked as you go.
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Certificate
EIC, EICR or Minor Works, filled in from the job and signed on your phone.
Key benefits of Ohmly
Less time on paperwork, more time on paid work, and customers who come back to you.
Certificates that fill themselves in
EIC, EICR and Minor Works, plus the board schedule and labels, written from the job. Check it, sign it on your phone, done.
Test results straight onto the certificate
Each reading is recorded once and checked against your design as you go, so a problem shows up while you are still at the board.
Quotes out the same day
Priced from the job at your own rates, and sent while the customer still remembers you.
Inspections that turn into paid work
Price each EICR observation and Ohmly writes the remedial works quotation for you.
Your brand in your customer’s hands
Certificates and a plain-English summary you can send, carrying your business details, and your logo on the certificates with Pro.
First in line for the next inspection
Every job kept against the property, and a reminder when an inspection falls due, so your customer hears from you first.
How much could Ohmly save you?
A quote written by hand takes about half an hour, usually unpaid, at the end of the working day. At a UK sole trader’s effective rate of £40 to £75 an hour, that one quote costs you £20 to £37.50 of your time.
And most quotes do not win the job: 3 to 4 quotes for every job won. Spend less time on the ones that go elsewhere.
Ohmly generates the quote from the job you set up by answering a few simple questions, and writes the certificate from the same job, so most of that half hour becomes a quick check and a send.
Seven free calculators, always at your fingertips.
The calculator hub is one tap from the home screen, with no subscription and no time limit, and it works with no signal. Cable sizing, voltage drop, Zs and “Which RCD do I need?” answer through the same engine that designs every circuit in Ohmly, so the hub and the wizards always agree.
Cable sizing
The cable and protective device a circuit needs, sized exactly as the wizards size it.
Voltage drop
The voltage drop on a cable you have chosen, against the limit for the circuit.
Earth fault loop impedance (Zs)
The Zs a circuit will have, and the maximum its device allows.
Adiabatic equation
Minimum protective conductor size from fault current and disconnection time.
Prospective fault current
The maximum fault current from a measured loop impedance, and whether a device covers it.
Conduit and trunking capacity
How many cables a run will take, by the IET factor method.
Which RCD do I need?
The RCD any circuit the wizards design needs, from the same decision the wizard makes.
These calculators state what they cannot determine. Where a value is not in the reference data, Ohmly says so rather than assuming one. Cable sizing and voltage drop work on single-phase final circuits, 1.0 to 16 mm², in flat twin and earth, a thermosetting multicore or SWA, and cable sizing chooses a device from 6 to 63 A. Zs works on Type B, C and D circuit-breakers and RCBOs, and on BS 88, BS 1361 and BS 3036 fuses.
Ohmly checks your work before you start
Every check runs against your design, on your supply, before a cable is pulled. If something is missing, Ohmly tells you exactly what, while it still costs nothing to fix.
- AFDD requirement
- SPD requirement
- Open-PEN on a PME supply
- Main bonding size
- Earthing conductor size
- Supplementary bonding
- Earth electrode
- Maximum demand
- Zs against the device
- RCD requirement
- Bathroom zones
- Cable size and derating
- Voltage drop
- Discrimination
- Adiabatic check
- Missing parts named, with a one-tap fix where one is safe
Ohmly wants your work to be safe before it makes a penny from you. So nothing that keeps an installation safe sits behind a payment.
Free on every plan, for good: every safety check, from AFDD and SPD to bonding, earthing, Zs and cable sizing; every warning; the live circuit check; the installation checklist with its safe isolation steps; test readings checked against your design; and the calculators, including “Which RCD do I need?”. The terms of service put that promise in writing.
Quick answers when you need them, free on every plan.
Not every job is a full design. These handle the quick questions and the small jobs in between.
The right RCD, with the reasons
Answer a few questions and Ohmly tells you which RCD the circuit needs, and why. Fault current, adiabatic and conduit fill calculators sit alongside.
Know if the supply can take it
See what an EV charger, heat pump, battery or extra shower does to maximum demand before you quote.
Instrument calibration, looked after
Ohmly reminds you before each instrument is due for calibration, on your own interval.
Cable lengths you can quote on
Place the points on a floor plan and Ohmly estimates every run, with an allowance for cutting.
Repeat work starts from the last job
Duplicate a job or save it as a template, so the next board change never starts from a blank page.
Ohmly draws the circuit so everyone knows what’s installed.
Every circuit is drawn as you set up the job, so you can see exactly what is installed and where: on the day, and when you come back to the same house years later. When plans change, add to the drawing and Ohmly checks the change as you make it.
Clear, understandable diagrams
Every circuit in a consistent symbol set and BS 7671 colours, with a front view of the board and a schematic whenever you need one.
Easily updated when plans change
Customer wants another light? Add it, and Ohmly shows green when the circuit is complete and names anything missing.
22 job types
From everyday circuits to EV chargers, solar, three-phase boards and special locations, plus alterations and inspections.
Adding an intermediate switch to the hall and landing lighting. Conductor colours to BS 7671; black and grey are the strappers of the three-core.
Ohmly is always by your side
In the loft, the basement, the plant room or a new build with no meter yet, Ohmly works exactly the same. Everything runs on your phone, with no login and nothing to wait for.
Full function at zero bars
Not a cut-down offline mode. The same app doing the same things, with or without signal.
Open it and start
No account, no email to confirm, no invite. Install it and start your first job.
Your work stays yours
Your customers and job records live on your phone, not on someone else’s server, and you can back them up whenever you like.
Three plans. Pick the one that fits your work.
On every plan you can design, check and test every job, and your first job’s certificates are free to issue. Pro issues the certificates for every job after that and adds the business side. Pro+ adds commercial and specialist work.
Free
Free permanently. Not a trial.
For apprentices learning the trade, and for any electrician who wants the safety checks on every job. Your first job is free to issue.
- Starter circuits: lighting, ring final, radial, cooker, shower, immersion, smoke and heat detection, outdoor and consumer unit layout
- The calculator hub: seven calculators, including cable sizing, voltage drop, Zs and “Which RCD do I need?”
- Every safety determination, in full
- The installation checklist, including safe isolation
- Live power-path validation and missing-component warnings
- Cable sizing, voltage drop, Zs, RCD and adiabatic
- Test results, checked against the design as you go
- Record an existing installation as found, and its EICR observations
- Calibration reminders from your own interval
- EIC, EICR and Minor Works certificates, signed and issued
- Test readings spoken or typed: a spoken reading is saved as you say it, with the words heard shown, and can be edited or deleted
- Particulars for EV charging points and stationary batteries on the EIC
- A danger notice listing a job’s C1 dangers, as a PDF for the customer
- The G98 Form B, filled in from the job for you to send to the DNO
- Start a re-inspection from an issued EIC or EICR
- Consumer unit schedule on screen, way labels and notices
- Help, lessons, practice questions, glossary and symbol library
- PNG export and the share sheet
- Up to five saved jobs, circuits uncapped, your first job free to issue
- Ad-supported. Never on the drawing canvas, in a wizard, in the checklist, or beside a safety warning
Pro
£14.99 a month, or £139.99 a year (£11.67 a month, saving 22%). First month free.
For electricians who quote and certify every week: unlimited jobs, priced quotes including remedial works, invoices for any job, and your branding on every document.
- Unlimited jobs
- Branded PDF export with your logo and scheme number
- SVG vector export
- Priced materials list, shopping list and job costing
- Your own prices for materials, replacing Ohmly's estimates
- Customer quote generation
- Invoices for any job
- EV charger, solar PV, battery and swimming pool wizards
- Heat pump, underfloor heating and sauna wizards
- No advertising
Pro+
£21.99 a month, or £199.99 a year (£16.67 a month, saving 24%). First month free.
For commercial, three-phase and specialist work, and for looking after landlords and repeat customers: inspection reminders, guided job workflows and CAD export.
- Everything in Pro
- Emergency lighting and fire alarm wizards
- Three-phase board design with phase balancing
- Motor circuit wizard
- Agricultural, caravan park and marina supplies
- Property history, landlord portfolios and EICR recall
- Job workflows for board changes, surveys and rewires
- Timed fault log for billing
- DXF export for CAD
- No advertising
Your monthly Pro subscription costs less than 10-20 minutes of paid work for most qualified electricians.
Charged through Google Play in pounds sterling. Google shows the final amount, including any tax, before you confirm. Compare the plans in full.
Your questions, answered.
Will my scheme provider accept a certificate from Ohmly?
Ohmly’s certificates are set out in a clear layout of Ohmly’s own, signed by you on your phone and locked the moment you issue them. Before you issue, Ohmly lists in red anything still missing, and shows you the list again as you issue.
Works with whichever scheme you’re registered with. Your certificate isn’t scheme-branded, and notification stays in your scheme’s own portal, just as it does today.
Does Ohmly work with no signal?
Yes, fully. Every wizard, check, drawing, test record and certificate works at zero bars: in the loft, the basement or a new build with no meter yet. There is no login and no Ohmly server to reach, so there is nothing to wait for.
Where is my data kept?
On your phone. Ohmly has no servers and no accounts, so your jobs, customers, drawings and certificates stay on your device unless you choose to share them.
The free plan’s advertising and Google Play’s billing collect details about the phone, never your work. Google Drive backup, if you switch it on, copies your records to your own Google account. When you say a test reading, Online speech is the default, so what you say goes to your phone’s online speech service unless you choose On-device in Settings. The privacy policy sets out exactly what each one collects.
Are there adverts?
Only on the free plan, and never while you are working: not on the drawing, in a wizard, in the checklist or beside a safety warning. You see a strip on the home screen, and a full screen when you close a job or share an exported drawing. Pro and Pro+ have none.
How does Ohmly check its figures against BS 7671?
Every figure Ohmly uses is checked against BS 7671:2018+A4:2026, read from a named edition and re-derived from the printed formula. Ohmly gives you the regulation number to look up, and the judgement on site stays yours, as it should.
Does Ohmly do invoicing or Part P notification?
Ohmly does the design, the checks, the quote and the certificate. On Pro, it also invoices any job, from the shared quote or from work and prices you type: a deposit, the balance or any amount, each shared as a PDF and marked paid when the money arrives. Your books and accounts stay with the software you already use for them.
Part P notification stays in your scheme’s own portal, as it does today, and Ohmly records the scheme, the date and the reference against the job.
Is Pro worth it if I only do a few jobs a month?
Yes. If you write even one quote a month, Pro costs less than the time that quote takes you by hand. Free never expires, and your first job is free to issue.
Can an apprentice use Ohmly?
Yes, and it is a great way to learn. The wizard asks the questions a circuit needs. The lessons, practice questions, glossary and calculators are free and work with no signal.
How many certificates can I issue on the free plan?
Your first job is free to issue, with every certificate it needs: EIC, EICR and Minor Works, as long as it used none of the Pro or Pro+ wizards. That allowance is once, not once a month. You can design as many circuits as you like on any plan, and Pro removes the limit on issuing and on saved jobs.
Does Ohmly work with my test instruments?
Yes, with every make and model. You enter the readings, so there is nothing to pair and no list of supported meters. If your tester’s software saves its readings as a CSV file, share that file to Ohmly and check each reading as it comes in.
What happens when BS 7671 changes?
Ohmly is built to BS 7671:2018+A4:2026. Its reference data records the document and edition each figure was read from, so Ohmly knows exactly which of those values an amendment touches, and updates arrive through Google Play like any other app. A certificate you have already issued stays exactly as you signed it.
Will Ohmly run on my phone?
Any phone on Android 8.0 or later. Google Play will tell you before you install if yours is older. You do not need a camera, only for photos of the job or the board.
Is there an iPhone version?
Ohmly is Android first. An iPhone version is on our list for after launch, and the date will be on this page as soon as there is one.
What happens if I lose my phone?
Your work is safe as long as you keep a copy. In Settings, Back up and restore, Back up everything saves every job, certificate, test result and customer to one file you can keep wherever you like, and on Android 12 and later with a screen lock set, Google Drive backup copies your records to your own Google account.
On the new phone, install Ohmly and restore from the backup in Settings before you start work on it, because a restore replaces what is there. Keep the backup file until your jobs are showing on the new phone. While Drive backup is off, Ohmly reminds you to take a backup now and then.
Is a certificate from Ohmly legally valid?
Yes, in the same way as any certificate: it stands because a competent person inspected and tested the installation, signed it, and what it says is right. Ohmly lays out the forms, does the arithmetic and keeps the record straight. The inspection, the testing and the signature are yours.
Put Ohmly to work on your next job.
Install it, add the job and see what Ohmly writes for you.