Blank psychrometric charts to download and print (PDF, SVG)
Blank Mollier h-x and Carrier psychrometric charts are free to download here, with no sign-up, as vector PDF (A4, A3), SVG or DXF — in SI and I-P units and for pressures from sea level to 5 000 ft.
Thirteen ready-made sheets: Mollier h-x and Carrier, SI and I-P, at sea level and at altitude. Vector PDF for A4 and A3, SVG for the plotter. Free, no sign-up, nothing stamped across the drawing.
Every sheet is drawn by the same calculation core as the application — saturation pressure from the Hyland-Wexler equations, enthalpy and humidity ratio per ASHRAE Handbook — Fundamentals 2021. What you read off the paper is what the app computes, to well inside the width of a pencil line.
The drawing itself carries no words, only symbols and units, so a single file serves every language. Line weights are absolute in millimetres (0.13 mm minor grid, 0.5 mm saturation line) and the sheet knows its own physical size, so an A3 file prints as a true A3 sheet and the scale in the footer stays honest.
Draw your own chart
Set the boundary conditions, the paper and what the sheet should carry. The preview is the same drawing that comes out of the download — nothing is rendered twice.
p = 101.3 kPa · t -20…50 °C · x 0…30 g/kg · A3 landscape
Download
The generator draws the grid. Points and processes are drawn into it by the application, which exports the same formats — PDF, DXF or PNG.
This one is already prepared
The same sheet is in the ready-made set, so you can take it straight from the server — a stable link you can share, and no waiting for the browser.
Which sheet do you need
| Decision | SI | I-P |
|---|---|---|
| Units | °C, g/kg, kJ/kg — European practice, EN and ISO | °F, gr/lb, Btu/lb — US practice, ASHRAE |
| Chart type | Mollier h-x: humidity ratio horizontal, enthalpy on an oblique axis — central Europe | Carrier: dry-bulb horizontal, humidity ratio vertical — ASHRAE and manufacturers’ selection software |
| Pressure | By the altitude of the site, not the address of the office — Altitude and pressure table | The same, only in feet and inches of mercury |
Mollier h-x charts
How to read a Mollier chart →Humidity ratio along the horizontal axis, enthalpy oblique — the central-European convention. Temperature rises to the right and the saturation line sweeps up from the lower left.
Psychrometric charts (Carrier)
How to read a psychrometric chart →Dry-bulb temperature horizontal, humidity ratio vertical — the ASHRAE convention. Wet-bulb lines fall to the right and the saturation line closes the chart on the left.
Working in CAD?
The same charts are available as DXF with named layers — insert one into your drawing, switch off what gets in the way and draw your process on your own layer.
Psychrometric chart as DXF →Altitude and barometric pressure
A sheet is drawn for one pressure and that pressure is printed in its stamp. Pressure falls with altitude, so a sea-level sheet read at height gives a slightly different relative humidity and dew point.
Up to about 300 m the difference stays under 3.5 % and you will not see it at the resolution of a pencil line. Higher up, take the sheet for your altitude — or generate your own.
| Place | Altitude | Pressure | Which sheet |
|---|---|---|---|
| London | 25 m | 101.0 kPa | sea level — Mollier h-x chart · Psychrometric chart (0.3 %) |
| Denver | 1,609 m | 83.4 kPa | generator (7.7 %) |
| Nairobi | 1,684 m | 82.7 kPa | generator (8.7 %) |
| Johannesburg | 1,767 m | 81.8 kPa | generator (9.8 %) |
| Mexico City | 2,240 m | 77.2 kPa | generator (16.5 %) |
| Addis Ababa | 2,405 m | 75.6 kPa | generator (18.9 %) |
| Bogotá | 2,582 m | 73.9 kPa | generator (21.6 %) |
| Quito | 2,854 m | 71.4 kPa | generator (25.8 %) |
| La Paz | 3,782 m | 63.4 kPa | generator (41.7 %) |
City elevations: GeoNames (CC BY 4.0). Pressures are computed by the same core that draws the sheets.
Printing the sheets
A4 or A3 on an office printer
Both PDFs are vector, so they come out at the printer’s full resolution. Switch “Fit to page” off and print at 100 %: the driver otherwise shrinks the sheet by a few percent and the scale printed in the footer becomes a lie.
Check the scale before you measure on it
The footer carries a 100 mm control line with end ticks (50 mm on narrow sheets, and it says so). Lay a ruler on it. If it measures 100 mm, the mm-per-unit figures in the stamp are true and you can take differences straight off the paper.
A2 to A0 on a plotter
Send the SVG. Its width and height are in millimetres, so Inkscape, a plotter RIP or a copy shop gets the physical size right without being told. The A3 PDF enlarges cleanly too — a vector just saves one conversion. Plotting from CAD? Take the DXF instead.
Photocopier and black-and-white printing
Three variants are drawn in a single ink. Pale blue φ curves vanish on a copier, so the mono sheets separate the families by line weight and dash pattern instead of colour.
What you may do with the files
Free to use, including in commercial projects and in teaching. You may print the sheets, hand them out and share the files unchanged, and you may of course draw on your own printout — that is what a blank chart is for.
What you may not do: sell the files, or remove the source identification from them. Formally this is not a Creative Commons licence — CC BY would require attribution on every printout, which nobody does, and CC BY-ND would forbid drawing on the sheet, which is the whole point.
Frequently asked questions
Are the charts really free? +
Yes. No sign-up, no e-mail, no watermark across the drawing. The only branding is the mark and the domain in the footer strip, outside the plotting area.
Which sheet should I pick? +
Pick the unit system first: SI (°C, g/kg, kJ/kg) in Europe, I-P (°F, gr/lb, Btu/lb) in the United States. Then the chart type — Mollier h-x is the central-European convention, the Carrier psychrometric chart the ASHRAE one; the physics is identical, only the axes are swapped. Finally the altitude of the site.
Why does altitude matter on a psychrometric chart? +
Barometric pressure sets the saturation humidity ratio. At 1 000 m the pressure is about 89.9 kPa instead of 101.3 kPa, and saturated air at 20 °C holds roughly 16.6 g/kg instead of 14.7 g/kg — about 13 % more. A sea-level sheet used at altitude therefore gives a wrong relative humidity and a wrong dew point. The whole sheet is drawn for one pressure, printed in the footer.
May I use the chart in a report, in a thesis or in class? +
Yes, all of that is covered, including commercial projects. Keep the footer strip intact so a reader can see which pressure and which unit system the sheet was drawn for.
I need a different temperature range or pressure. +
Use the generator on this page: you set the pressure or the altitude, the temperature and humidity ranges, the paper format and the layers, and out comes a PDF, an SVG or a DXF. Beyond that, the application draws processes into the same chart and computes the states.
What is the difference between the PDF and the SVG? +
Both are vector and identical in content. The PDF is what you send to a printer; the SVG is what you send to a plotter or open in Inkscape or a CAD tool, because its dimensions are stated in millimetres. Only the A3 SVG is published — a vector scales to any size on its own.
Can I get the chart into AutoCAD? +
Yes, every variant is also published as DXF (R12) with named layers, drawn 1:1 in millimetres. Insert it into your drawing as a background, switch off the layers you do not need and draw your process on your own. AutoCAD, BricsCAD, DraftSight, LibreCAD, QCAD and FreeCAD all open it.
Can I print the sheet on A4 and measure on it? +
Yes. The A4 PDF is drawn to the same scale rules as the A3 one, only smaller, and the footer states how many millimetres one unit is. Print at 100 %, check the control line with a ruler, and you can take differences straight off the paper. On A4 you read one significant figure less than on A3 — for a check calculation that is enough, for a report take the A3.
Does the sheet still work above 50 °C, for drying? +
No, the ready-made sheets stop at 50 °C ( 122 °F). Drying runs far beyond that, so use the generator on this page: set the temperature range you need and it draws the sheet for it. Above about 90 °C the saturation line stops being meaningful at atmospheric pressure, so that is where the generator stops too.
What is the difference between a Mollier chart and a psychrometric chart? +
The physics is identical, the axes are swapped. The Mollier h-x chart has humidity ratio horizontal and enthalpy on an oblique axis — the central-European convention. The Carrier psychrometric chart has dry-bulb temperature horizontal and humidity ratio vertical — the ASHRAE convention. A state point sits in a different place on the sheet, but reads the same numbers.
Need the processes drawn in, not just the grid?
PsychroView chains heating, cooling, heat recovery, humidification and mixing on the same chart and exports the result as vector PDF, DXF or PNG.
Launch the appDownloading. The same sheet with the processes drawn in and the states calculated is in the application.