What you can calculate with the single girder calculation:

Here you can dimension single timber girders with line load.

Mind the following limitations:

Loads are distributed evenly (=line load).
Girder is horizontal.
Necessary size of bedding, danger of possible tilting or crippling are not checked.
Snow load calculation is incorrect above 2000m MSL.
Calculation is valid for residantial buildings, not for assembly rooms, shops etc.
Live load is assumed to be of medium duration (-6 month). Tis is not allowed for industria factories, barns, storages and places with extensive gatherings.
Superelevation is not considered, because do it yourselfers hardly have the chance to accomplish that. For that reason the 3. confirmation of serviceability doesn't make sense.

Here an explanation of the values that have to be entered:

Dead Load / Selfweight

Enter the weight of the whole construction that lies on the girder. Use kilograms. Enter the whole weight lasting on the girder, NOT the wieght per meter etc.

If you have problems to calculate the weight checkout help here:

Maximum Live Load

Enter the maximum live load in kg. Standard live loads that are assumed for residential structures are between 200 and 400 kg/m2. Again calculate the whole weight lasting on the girder.

Snowload

Enter the maximum snowload lasting on the whole girder.

For further information click the info button :

Girder Length

Enter the clearance between the uprights in meters.

planned girder dimensions

Enter the planned dimensions of the girder. First guess which dimensions are sufficient, you will get the result after calculation.

Service Class

Enter in which surrounding the girder will be used.

Further information here:

Timber Category

Enter the strength grade of the used Timber. Pinewood of standard quality is C24.

Here you get more information: