There are many reasons because of which variances may occur in SAP. When an invoice is received from a vendor and before a payment is made, SAP R/3 can be configured to perform a variety of checks for each invoice item. The main types of variances which come up in SAP are Quantity variance, Price variance, PO Price Quantity variance and Date Variance. Let me discuss each of these in detail.

Quantity Variance - SAP calculates this variance comparing the delivered quantity with the quantity invoiced.

Price Variance - SAP compares the invoice price with the purchase order price in generating this variance.

Date Variance - In date variance, SAP R/3 compares the planned delivery date with the invoice entry date resulting in a variance.

Purchase Order Price Quantity Variance - In case invoice is received before goods are recived physically SAP compares GR quantity and Invoice quantity, both, in terms of PO units and PO price units. Similary, if goods are received before invoice is received, PO quantity and invoice quantity are compared resulting in a variance.