Odds 'n' Sods of Information and Opinion

Carrying Weight Concept Line Calculator

When trying to determine the weight of an AFTMA accurate fly line when a grain weight scale is not available, use this spreadsheet instead.


Clicking on the image above will download the spreadsheet to your computer. You will need a program capable of using Microsoft Excel spreadsheets to use this file.

The spreadsheet is currently arranged to quickly determine the weight of a double taper line at five foot intervals up to 60’. However the Belly Length cells in underlined blue can be amended to cover DT lines of any length and WF lines as well. Just follow the instructions below.

To use the spreadsheet, first use the manufacturer’s specifications to determine:
  • tip length (usually .5’ to 1’ long)
  • front taper
  • belly length (the section between front and rear taper)
  • ignore rear taper

The value “Front Taper” in underlined blue on the spreadsheet equals the tip plus front taper taken from the manufacturer’s specifications.

The value “Belly Length” in underlined blue on the spreadsheet equals the tip plus front taper plus belly section taken from the manufacturer’s specifications. In other words, it’s the total length of the head minus the rear taper.

Enter the “Front Taper” value as determined above, across from the AFTMA line rating for your line.

Across the top under “Belly Length” enter the head length as determined above or use one of the value already entered.

The cell under the belly length you have entered and on the row for your line rating, find the weight of the head.

If you wish to include the rear taper, first subtract one third of the length of the rear taper from the overall head length (determined by including the rear taper), then enter that value in one of the “Belly Length” cells.

If the fly line is not built to the AFTMA standard and the manufacturer has supplied the head weight taken at the 30’ mark, then enter that value under “AFTMA Weight” across from the appropriate line rating number.

If you have any trouble using the spreadsheet, feel free to
email me.