rrdgraph - Round Robin Database tool grapher functions


rrdtool graph filename [option ...] [data definition ...] [data calculation ...] [variable definition ...] [graph element ...] [print element ...]


The graph function of RRDtool is used to present the data from an RRD to a human viewer. Its main purpose is to create a nice graphical representation, but it can also generate a numerical report.


rrdtool graph needs data to work with, so you must use one or more data definition statements to collect this data. You are not limited to one database, it's perfectly legal to collect data from two or more databases (one per statement, though).

If you want to display averages, maxima, percentiles, etcetera it is best to collect them now using the variable definition statement. Currently this makes no difference, but in a future version of rrdtool you may want to collect these values before consolidation.

The data fetched from the RRA is then consolidated so that there is exactly one datapoint per pixel in the graph. If you do not take care yourself, RRDtool will expand the range slightly if necessary. Note, in that case the first and/or last pixel may very well become unknown!

Sometimes data is not exactly in the format you would like to display it. For instance, you might be collecting bytes per second, but want to display bits per second. This is what the data calculation command is designed for. After consolidating the data, a copy is made and this copy is modified using a rather powerful RPN command set.

When you are done fetching and processing the data, it is time to graph it (or print it). This ends the rrdtool graph sequence.


The name and path of the graph to generate. It is recommended to end this in .png, .svg or .eps, but RRDtool does not enforce this.

filename can be '-' to send the image to stdout. In this case, no other output is generated.

Time range
[-s|--start time] [-e|--end time] [-S|--step seconds]

The start and end of the time series you would like to display, and which RRA the data should come from. Defaults are: 1 day ago until now, with the best possible resolution. Start and end can be specified in several formats, see AT-STYLE TIME SPECIFICATION and the rrdgraph_examples manpage. By default, rrdtool graph calculates the width of one pixel in the time domain and tries to get data from an RRA with that resolution. With the step option you can alter this behaviour. If you want rrdtool graph to get data at a one-hour resolution from the RRD, set step to 3'600. Note: a step smaller than one pixel will silently be ignored.

[-t|--title string] [-v|--vertical-label string]

A horizontal string at the top of the graph and/or a vertically placed string at the left hand side of the graph.

[-w|--width pixels] [-h|--height pixels] [-j|--only-graph]

The width and height of the canvas (the part of the graph with the actual data and such). This defaults to 400 pixels by 100 pixels.

If you specify the --only-graph option and set the height < 32 pixels you will get a tiny graph image (thumbnail) to use as an icon for use in an overview, for example. All labeling will be stripped off the graph.

[-u|--upper-limit value] [-l|--lower-limit value] [-r|--rigid]

By default the graph will be autoscaling so that it will adjust the y-axis to the range of the data. You can change this behaviour by explicitly setting the limits. The displayed y-axis will then range at least from lower-limit to upper-limit. Autoscaling will still permit those boundaries to be stretched unless the rigid option is set.


Sometimes the default algorithm for selecting the y-axis scale is not satisfactory. Normally the scale is selected from a predefined set of ranges and this fails miserably when you need to graph something like 260 + 0.001 * sin(x). This option calculates the minimum and maximum y-axis from the actual minimum and maximum data values. Our example would display slightly less than 260-0.001 to slightly more than 260+0.001 (this feature was contributed by Sasha Mikheev).


Where --alt-autoscale will modify both the absolute maximum AND minimum values, this option will only affect the minimum value. The maximum value, if not defined on the command line, will be 0. This option can be useful when graphing router traffic when the WAN line uses compression, and thus the throughput may be higher than the WAN line speed.


Where --alt-autoscale will modify both the absolute maximum AND minimum values, this option will only affect the maximum value. The minimum value, if not defined on the command line, will be 0. This option can be useful when graphing router traffic when the WAN line uses compression, and thus the throughput may be higher than the WAN line speed.


In order to avoid anti-aliasing effects gridlines are placed on integer pixel values. This is by default done by extending the scale so that gridlines happens to be spaced using an integer number of pixels and also start on an integer pixel value. This might extend the scale too much for some logarithmic scales and for linear scales where --alt-autoscale is needed. Using --no-gridfit disables modification of the scale.


[-x|--x-grid none]

The x-axis label is quite complex to configure. If you don't have very special needs it is probably best to rely on the autoconfiguration to get this right. You can specify the string none to suppress the grid and labels altogether.

The grid is defined by specifying a certain amount of time in the ?TM positions. You can choose from SECOND, MINUTE, HOUR, DAY, WEEK, MONTH or YEAR. Then you define how many of these should pass between each line or label. This pair (?TM:?ST) needs to be specified for the base grid (G??), the major grid (M??) and the labels (L??). For the labels you also must define a precision in LPR and a strftime format string in LFM. LPR defines where each label will be placed. If it is zero, the label will be placed right under the corresponding line (useful for hours, dates etcetera). If you specify a number of seconds here the label is centered on this interval (useful for Monday, January etcetera).

 --x-grid MINUTE:10:HOUR:1:HOUR:4:0:%X

This places grid lines every 10 minutes, major grid lines every hour, and labels every 4 hours. The labels are placed under the major grid lines as they specify exactly that time.

 --x-grid HOUR:8:DAY:1:DAY:1:0:%A

This places grid lines every 8 hours, major grid lines and labels each day. The labels are placed exactly between two major grid lines as they specify the complete day and not just midnight.

[-y|--y-grid grid step:label factor]

[-y|--y-grid none]

Y-axis grid lines appear at each grid step interval. Labels are placed every label factor lines. You can specify -y none to suppress the grid and labels altogether. The default for this option is to automatically select sensible values.

If you have set --y-grid to 'none' not only the labels get supressed, also the space reserved for the labels is removed. You can still add space manually if you use the --units-length command to explicitly reserve space.


Place the Y grid dynamically based on the graph's Y range. The algorithm ensures that you always have a grid, that there are enough but not too many grid lines, and that the grid is metric. That is the grid lines are placed every 1, 2, 5 or 10 units. This parameter will also ensure that you get enough decimals displayed even if your graph goes from 69.998 to 70.001. (contributed by Sasha Mikheev).


Logarithmic y-axis scaling.

[-X|--units-exponent value]

This sets the 10**exponent scaling of the y-axis values. Normally, values will be scaled to the appropriate units (k, M, etc.). However, you may wish to display units always in k (Kilo, 10e3) even if the data is in the M (Mega, 10e6) range, for instance. Value should be an integer which is a multiple of 3 between -18 and 18 inclusively. It is the exponent on the units you wish to use. For example, use 3 to display the y-axis values in k (Kilo, 10e3, thousands), use -6 to display the y-axis values in u (Micro, 10e-6, millionths). Use a value of 0 to prevent any scaling of the y-axis values.

This option is very effective at confusing the heck out of the default rrdtool autoscaler and grid painter. If rrdtool detects that it is not successful in labeling the graph under the given circumstances, it will switch to the more robust --alt-y-grid mode.

[-L|--units-length value]

How many digits should rrdtool assume the y-axis labels to be? You may have to use this option to make enough space once you start fideling with the y-axis labeling.


With this option y-axis values on logarithmic graphs will be scaled to the appropriate units (k, M, etc.) instead of using exponential notation. Note that for linear graphs, SI notation is used by default.


Only generate the graph if the current graph is out of date or not existent.

[-f|--imginfo printfstr]

After the image has been created, the graph function uses printf together with this format string to create output similar to the PRINT function, only that the printf function is supplied with the parameters filename, xsize and ysize. In order to generate an IMG tag suitable for including the graph into a web page, the command line would look like this:

 --imginfo '<IMG SRC="/img/%s" WIDTH="%lu" HEIGHT="%lu" ALT="Demo">'

[-c|--color COLORTAG#rrggbb[aa]]

Override the default colors for the standard elements of the graph. The COLORTAG is one of BACK background, CANVAS for the background of the actual graph, SHADEA for the left and top border, SHADEB for the right and bottom border, GRID, MGRID for the major grid, FONT for the color of the font, AXIS for the axis of the graph, FRAME for the line around the color spots and finally ARROW for the arrow head pointing up and forward. Each color is composed out of three hexadecimal numbers specifying its rgb color component (00 is off, FF is maximum) of red, green and blue. Optionally you may add another hexadecimal number specifying the transparency (FF is solid). You may set this option several times to alter multiple defaults.

A green arrow is made by: --color ARROW#00FF00

[--zoom factor]

Zoom the graphics by the given amount. The factor must be > 0

[-n|--font FONTTAG:size:[font]]

This lets you customize which font to use for the various text elements on the RRD graphs. DEFAULT sets the default value for all elements, TITLE for the title, AXIS for the axis labels, UNIT for the vertical unit label, LEGEND for the graph legend.

Use Times for the title: --font TITLE:13:/usr/lib/fonts/times.ttf

If you do not give a font string you can modify just the sice of the default font: --font TITLE:13:.

If you specify the size 0 then you can modify just the font without touching the size. This is especially usefull for altering the default font without resetting the default fontsizes: --font DEFAULT:0:/usr/lib/fonts/times.ttf.

RRDtool comes with a preset default font. You can set the environment variable RRD_DEFAULT_FONT if you want to change this.

Truetype fonts are only supported for PNG output. See below.

[-R|--font-render-mode {normal,light,mono}]

This lets you customize the strength of the font smoothing, or disable it entirely using mono. By default, normal font smoothing is used.

[-B|--font-smoothing-threshold size]

This specifies the largest font size which will be rendered bitmapped, that is, without any font smoothing. By default, no text is rendered bitmapped.


RRDtool graphs are composed of stair case curves by default. This is in line with the way RRDtool calculates its data. Some people favor a more 'organic' look for their graphs even though it is not all that true.

[-a|--imgformat PNG|SVG|EPS|PDF]

Image format for the generated graph. For the vector formats you can choose among the standard Postscript fonts Courier-Bold, Courier-BoldOblique, Courier-Oblique, Courier, Helvetica-Bold, Helvetica-BoldOblique, Helvetica-Oblique, Helvetica, Symbol, Times-Bold, Times-BoldItalic, Times-Italic, Times-Roman, and ZapfDingbats.


If images are interlaced they become visible on browsers more quickly.


Suppress generation of the legend; only render the graph.


Force the generation of HRULE and VRULE legends even if those HRULE or VRULE will not be drawn because out of graph boundaries (mimics behaviour of pre 1.0.42 versions).

[-T|--tabwidth value]

By default the tab-width is 40 pixels, use this option to change it.

[-b|--base value]

If you are graphing memory (and NOT network traffic) this switch should be set to 1024 so that one Kb is 1024 byte. For traffic measurement, 1 kb/s is 1000 b/s.

[-W|--watermark string]

Adds the given string as a watermark, horizontally centred, at the bottom of the graph.

Data and variables

CDEF:vname=RPN expression

VDEF:vname=RPN expression

You need at least one DEF statement to generate anything. The other statements are useful but optional. See the rrdgraph_data manpage and the rrdgraph_rpn manpage for the exact format.

Graph and print elements
You need at least one graph element to generate an image and/or at least one print statement to generate a report. See the rrdgraph_graph manpage for the exact format.


the rrdgraph manpage gives an overview of how rrdtool graph works. the rrdgraph_data manpage describes DEF,CDEF and VDEF in detail. the rrdgraph_rpn manpage describes the RPN language used in the ?DEF statements. the rrdgraph_graph manpage page describes all of the graph and print functions.

Make sure to read the rrdgraph_examples manpage for tips&tricks.


Program by Tobias Oetiker <>

This manual page by Alex van den Bogaerdt <>