Online calculation form

Online calculation form

Would it be possible to get some assistance with my calculation form please.
My form has 3 fields:-
Total Floor Area of Bulding m² Cost per m² (1.5) Total Cost
When the user inputs their 'Floor Area' and clicks 'Calculate', the form
will multiply their Total Area by the 'Cost Per M²' and show the answer in
the 'Total Cost' field
my form :-
<form action="" method="post" name="quote_calculator">
<table width="317" border="0" cellspacing="0" cellpadding="0">
<tr>
<td width="198">Total Floor Area of Bulding m²</td>
<td width="119"><div align="right">
<input name="area" type="number" size="15" maxlength="15">
</div></td>
</tr>
<tr>
<td>Cost per m²</td>
<td><div align="right">
<input name="cost" type="text" value="1.5 AED" size="15"
maxlength="7" readonly>
&nbsp;</div></td>
</tr>
<tr>
<td>Total Cost</td>
<td><div align="right">
<input name="area" type="number" size="15" maxlength="15">
</div></td>
</tr>
<tr>
<td>&nbsp;</td>
<td><div align="right">
<input type="submit" name="submit" id="submit" value="Submit">
</div></td>
</tr>
</table>
</form>
Any help or solutions that you can offer will be very appreciated.
With thanks
Paul