Never built variants in italics.
Military variants listed are new build only. All other variants are conversions of existing airframes.
| 367-80 | Prototype | Test Bed. 127’10” length. 130′ span. 11′ fuselage width. Prototype for both the 707 (civilian) and KC-135 (military) variants and narrower in cross section than both the production lines. |
| 707-120 | Basic | 145’1″ length. 130’10” span. 12’4″ inches fuselage width. P&W JT3C-6 turbojets. |
| 707-320 | Stretch | 152’11” length. 142’5″ span. 12’4″ inches fuselage width. P&W JT4A turbojets. |
| 707-220 | Reeingined 120 | 145’1″ length. 130’10” span. 12’4″ inches fuselage width. P&W JT4A-3 turbojets. |
| 707-420 | Reengined 320 | 152’11” length. 142’5″ span. 12’4″ inches fuselage width. RR Conway Mk508 turbofans. |
| 720 | Shrink | Shorter-range shrink. 136’9″ length. 130’10” span. 12’4″ fuselage width. P&W JT3C turbojets. |
| 720B | Reeingined 720 | 136’9″ length. 130’10” span. 12’4″ fuselage width. P&W JT3D turbofans. |
| 707-120B | Reengined 120 | 145’1″ length. 130’10” span. 12’4″ inches fuselage width. P&W JT3D turbofans. |
| 707-320B | Modified and reengined 320 | Increased wing span, modified wing devices, increased MTOW. 152’11” length. 142’8.5″ span. 12’4″ inches fuselage width. P&W JT3D turbofans. |
| 707-320C | Convertible 320 | 320B with stronger floor and cargo door. Could be used for passengers, cargo, or both. 152’11” length. 142’8.5″ span. 12’4″ inches fuselage width. P&W JT3D Turbofans. |
| 707-700 | Reengined 320C | Only one built (converted 320C) to test validity of high-bypass turbofans on the airframe. Cost of conversion to new engines found unjustified for new production aircraft. 152’11” length. 142’8.5″ span. 12’4″ inches fuselage width. CFG-56 turbofans. |
| 707-520 | Reengined 120 | Reengined 120 with RR Conway 10 engines. |
| 707-520B | 320B stretch | 2′ stretch of the 320B with JT3D-5A turbofans. |
| 707-620 | 120 Stretch | 10′ stretch of the 120 with Bristol 511 engines. |
| 707-720 | 320 with IGW | Increased Gross Weight variant of the 320 with Bristol 511 engines. |
| 707-320-101 | 320 with enlarged lower lobe | 320 with an enlarged lower lobe for passenger seating on a lower deck forward of the wing and more cargo aft of the main gear. |
| 707-520-X | Double decker development | Double decker with low wing. Length 191’7″. |
| 707-520-2X | 520-X shrink | Double decker with low wing. Shorter than the above. |
| 707-520-X3 | Double decker development | Double decker with high wing. Length 144’2″. Span 142’5″. |
| 735 and 738 | Swing tail cargo variants | 735 had an upward swinging tail and 738 a sideways swinging one. Both enabled cargo loading through the resultant opening. |
| KC-135A | Boeing model numbers 717-100/146/148 | P&W J57 turbojets |
| C-135A | Boeing model number 717-157 | P&W J57 turbojets |
| C-135B | Boeing model number 717-158 | P&W TF33 turbofans and wider span stabilizer |
| KC-135B | Boeing model number 717-166 | P&W TF33 turbofans and wider span stabilizer |
| C-135F | Boeing model number 717-164/165. Cargo/Tanker for the French Air Force | Upgraded to CFM F108 turbofans in 1985-88 |
| RC-135A | Boeing model number 739-700 | P&W J57 turbojets |
| RC-135B | Boeing model number 739-445B | P&W TF33 turbofans |