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Online Calculator: Bending Moments

{CalQlata © 01/01/20}

The bending moments calculator allows you to position one or two supports and up to six point loads along a straight beam and calculate the bending moments at any of the forces or supports entered. Go to the bottom of the page for help with its use.

Enter beam length:     

Support Positions (from left-hand end):

Positions & Forces:
Label Support Position Force Position Force Magnitude
(from LH-End) (from LH-End) (down='+ve' up='-ve')

Forces Bending Moments:
Label @ Supports @ Supports @ Forces sum of moments


This Bending Moments calculator is accessible from anywhere in the website using the shortcut key; "Alt" + "b"
The "Reset" button clears all calculations on the page and reinstalls default values (this button may not respond in the FireFox browser).
Reset can also be achieved by pressing the "F5" key.
Hover your cursor over the symbols for an associated description.

The default values in this calculator provide a balanced system (two supports), but that requires an additional force (63.078) at support-1 to achieve it.

Positive forces act down, negative forces act up. Positive moments act anti-clockwise, negative moments act clockwise.
If you wish a force to act upwards, give it a negative value.
If you do not wish to include a particular force or a support, then simply delete its position.
You must keep the supports and forces within the beam length. If you try to specify a position outside this length, the calculator will assume the support concerned is to be ignored and will automatically delete it.
If you wish to find the bending moment at a position between the forces and supports, set the magnitude of one of the forces (at that position) to zero.


The list of values below the heading; 'sum of moments' is the sum of the bending moments about the forces minus the sum of the bending moments about the supports.
If two supports are included in the calculation these values should all equal zero if the calculation is correct. However, if one of your support forces is negative, an additional force of that magnitude at that support is required to maintain that balance.
If only one support is included in your calculation, a list of non-zero values will appear below this heading. These are the individual bending moments that would be required for balance; only one moment at the force-location specified is required.

Downloadable Version

A full, downloadable version of this calculator is available from this website at; Moments.

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