Measure the seal
Run a short packing trial and measure the tape used on several closures in millimetres. Use the average for a first estimate and record any variation by bag type.
Allow for waste
A simple estimate divides the total available tape length by measured tape per closure after allowing for your chosen waste percentage. The packaging studio lets you enter those values and shows its assumptions.
Compare like with like
The goods estimate alone excludes delivery, tax treatment, labour, damaged bags and any equipment cost. Add those items from your real quotations and records before calling one method cheaper.