Looking at the Sheldon Brown gear calculator and the one found on the Wabi site show two significantly different calculations. i.e., the Wabi calc (for 700c) for a 48/18 reads to be a 69gi, but when using the Sheldon calc, and after selecting the correct tire size and crank length reads to be a 67.4gi. Which is more accurate? Which calculator do you all use? Thanks.

All City.

I use www.gear-calculator.com. You can calculate a bunch at once, and it's interactive.

This one has passed around here a lot
https://software.bareknucklebrigade.com/

It even calculates your sw8 skid patches

I use an iOS app.

Haven't actually looked into if it;s accurate or not, but this one's simple and quick to use.
https://deafpigeon.co.uk/gear-calculator.php

Thanks for all the links, everyone!

Interesting - the All City calc matches that of Sheldon's, and the Deaf Pigeon matches that of Wabi's. The ones that have the tire size selection match up and the ones that don't match up...

The ones without specific size probably round up to 27 for a 700c(it's more ~26.7),hence the bigger number. I usually just calculate myself,easy enough. Chainring/cog x Tirediameter

Thanks. How does the tire width and crank arm length fit into this - as used on the Sheldon gear calculator?

Increased width also increases height,increasing overall diameter. The Crankarm length on Sheldons calculator is needed to calculate gain. It doesn't effect GI.

^^ Thanks.