Now in beta · for heating engineers
See where the heat goes.
Measure each room on your phone and HeatLossPro works out the heat loss through every wall, window and floor. Then it hands you a clear PDF that shows the customer exactly why each radiator is the size it is.
Beta build. Free to use while we test it with working engineers. Already approved? Sign in
Living room
Example room for illustration.
Made by a heating engineer who got fed up of doing it longhand.
How it works
Three steps, one room at a time.
Measure up
Length, width and ceiling height. If the room isn’t a rectangle, sketch the outline and the areas are worked out for you.
Pick from the lists
Wall type, glazing, floor and the rooms next door. Room and outside design temperatures are filled in for you by room type and region.
Send the PDF
Heat loss per room, radiator outputs, a room plan, your details and your customer’s. Ready to email before you leave the house.
Features
Built for the customer’s front room, not a desk.
Made for your phone
Big buttons and short questions you can answer with one hand while you’re holding a tape measure.
Odd-shaped rooms
L-shapes, bays and chimney breasts. Draw the outline once and the wall and floor areas follow.
Room plan on the report
Each room drawn with its dimensions, so the customer can see what was measured.
Radiator sizing
The output each room needs at the flow temperature you’re designing to, ready to match to a radiator.
Your name on it
Your logo and company details, plus your customer’s name and address, on every report.
Jobs saved to your account
Come back to a job, add the rooms you missed and send the report again. Only you can see your jobs.
The report
A report your customer can actually read.
Every figure is shown with where it came from, so the customer can see why one room needs a bigger radiator than the next.
- Heat loss for each room, split into walls, windows, floor, ceiling and ventilation
- Radiator output needed for each room
- A plan of each room with its dimensions
- Your company and customer details on the front
Heat loss report
Customer name · Address
Design temps
21 °C in / −2 °C out
Floor area
15.1 m²
| Element | Watts |
|---|---|
| Ventilation (1.5 ach) | 413 |
| External wall | 285 |
| Floor | 167 |
| Windows | 155 |
| Ceiling (bedroom above) | 78 |
| Room total | 1,098 W |
Example figures for illustration · Prepared with HeatLossPro
Beta build
Help shape HeatLossPro.
HeatLossPro is being tested by working heating engineers before it launches properly. Create an account and we’ll email you as soon as your place is approved.
- Free to use while it’s in beta
- Tell us what’s wrong or missing and it goes straight to the engineer building it
- Your jobs are saved to your account, so they’re on your phone and your laptop
- Expect changes as we go, and check the figures before you rely on them
Join the beta
Three steps, about a minute.
- Create your account with your email and a password.
- Confirm your email from the link we send you.
- We approve your place and email you to say you can start.
Already approved? Sign in to the calculator
FAQ
Questions engineers ask.
What does “beta” mean here?
HeatLossPro works, but it’s still being tested. Some of the features on this page are still being finished, things may change between versions, and you should check the figures before you rely on them. If something looks wrong, tell us and we’ll fix it.
What method does it use?
The standard room-by-room method used across the UK heating trade: heat lost through walls, windows, doors, floors and ceilings, plus ventilation, worked out at design indoor and outdoor temperatures.
Does it replace my own judgement?
No. It does the sums and keeps them tidy. You still check the inputs and the results before you size a system.
Who can see my customers’ details?
Each account’s jobs are stored separately, and only you can see yours. You can ask us to delete your account and jobs at any time.
How do I get access?
Create an account and confirm your email. Places in the beta are approved by hand while we test it, and you’ll get an email as soon as yours is ready.