The official 2026 GM Fleet order guide publishes 12 Sierra 3500HD dimension columns, not one universal size. Overall length runs from 236.30 inches for a Regular Cab long-bed pickup to 266.77 inches for a Crew Cab long-bed truck. Wheelbase spans 142–172 inches. SRW body width is 81.85 inches, while DRW width is 96.60 inches for long-bed Crew Cab and 96.62 inches for Double and Regular Cab. Published height spans 80.04–81.20 inches and rear clearance spans 10.39–11.22 inches. Match cab, bed, drive, SRW or DRW and any named header, then measure the equipped truck and intended space; catalogue dimensions exclude optional equipment and accessories and do not guarantee fit.
Direct answer: Sierra 3500HD length is 236.30–266.77 inches
The 2026 Regular Cab long bed is 236.30 inches long, Double Cab long bed is 257.24 inches, Crew Cab standard bed is 250.75 inches and Crew Cab long bed is 266.77 inches. The corresponding wheelbases are 142, 162, 159 and 172 inches.
Width, height and clearance require SRW or DRW selection. The smallest and largest figures are source-row endpoints, not tolerances for every configuration.
| Published dimension | Minimum | Maximum | Selection boundary |
|---|---|---|---|
| Overall length | 236.30 in | 266.77 in | Cab and bed |
| Wheelbase | 142 in | 172 in | Cab and bed |
| Body width | 81.85 in SRW | 96.62 in DRW | Rear-wheel arrangement and cab |
| Overall height | 80.04 in | 81.20 in | Cab, SRW/DRW and named column |
| Rear ground clearance | 10.39 in | 11.22 in | Cab and SRW/DRW |
Twelve official columns define the pickup bodies
The reviewed matrix contains eight Crew Cab columns, two Double Cab and two Regular Cab. TC identifies 2WD and TK identifies 4WD; the 2WD columns require Pro trim in their source descriptions.
Named AT4 and Denali Ultimate columns repeat TK body codes but remain separate because height and available DRW cells differ. Preserve both the code and header instead of normalizing the row.
| Body group | Source columns | Bed and rear-wheel coverage |
|---|---|---|
| Crew standard | TC30743, TK30743, AT4 TK30743, Denali Ultimate TK30743 | Standard bed; SRW |
| Crew long | TC30943, TK30943, AT4 TK30943, Denali Ultimate TK30943 | Long bed; base SRW/DRW; named source states vary |
| Double long | TC30953, TK30953 | Long bed; SRW/DRW |
| Regular long | TC30903, TK30903 | Long bed; SRW/DRW |
Complete exterior matrix
The table keeps GM's paired inch and millimetre displays and separates SRW from DRW. A blank means the reviewed response displayed no value for that combination; it is not zero and does not authorize a sibling value.
Base 2WD and 4WD body columns share geometry where displayed. Drive identity still remains part of configuration matching.
| Configuration | Wheelbase / length | Body width SRW / DRW | Height SRW / DRW | Rear clearance SRW / DRW |
|---|---|---|---|---|
| Crew standard TC30743/TK30743 | 159 (4037) / 250.75 (6369) | 81.85 (2079) / blank | 80.87 (2054) / blank | 11.18 (284) / blank |
| Crew long TC30943/TK30943 | 172 (4369) / 266.77 (6776) | 81.85 (2079) / 96.60 (2454) | 80.67 (2049) / 80.04 (2033) | 11.14 (283) / 10.39 (264) |
| Crew standard AT4 | 159 (4037) / 250.75 (6369) | 81.85 (2079) / blank | 81.20 (2062) / blank | 11.18 (284) / blank |
| Crew long AT4 | 172 (4369) / 266.77 (6776) | 81.85 (2079) / blank | 80.81 (2053) / blank | 11.14 (283) / blank |
| Crew standard Denali Ultimate | 159 (4037) / 250.75 (6369) | 81.85 (2079) / blank | 81.20 (2062) / blank | 11.18 (284) / blank |
| Crew long Denali Ultimate | 172 (4369) / 266.77 (6776) | 81.85 (2079) / 96.60 (2454) | 80.81 (2053) / 80.30 (2040) | 11.14 (283) / 10.39 (264) |
| Double long TC30953/TK30953 | 162 (4127) / 257.24 (6534) | 81.85 (2079) / 96.62 (2454) | 80.87 (2054) / 80.20 (2037) | 11.15 (283) / 10.39 (264) |
| Regular long TC30903/TK30903 | 142 (3596) / 236.30 (6002) | 81.85 (2079) / 96.62 (2454) | 80.94 (2056) / 80.24 (2038) | 11.22 (285) / 10.47 (266) |
SRW and DRW width must remain separate
Every populated SRW body-width cell is 81.85 inches. Long-bed Crew Cab DRW is 96.60 inches, while Double and Regular Cab DRW are 96.62 inches. Both metric displays round to 2,454 mm, but the official imperial values differ by two-hundredths of an inch.
The guide preserves that display instead of forcing one universal dually width. Body width is not labelled mirror-open or mirror-folded width and does not include every accessory or operating envelope.
Crew Cab standard and long beds differ by 16.02 inches
Standard-bed Crew Cab is 250.75 inches long on a 159-inch wheelbase, with 42.17 inches from cab to axle. Long-bed Crew Cab is 266.77 inches on a 172-inch wheelbase with a 55.24-inch cab-to-axle value.
The longer body adds 16.02 inches of overall length and 13 inches of displayed wheelbase. Those figures stay tied to the complete body column rather than becoming a generic box-length adjustment.
Regular and Double Cab are long-bed-only here
The reviewed Regular Cab is 236.30 inches long with a 142-inch wheelbase. Double Cab is 257.24 inches long with a 162-inch wheelbase. Both publish a 55.24-inch cab-to-axle value.
No standard-bed Regular or Double Cab appears in this Sierra 3500HD dimensions response. Absence is not a zero and is not permission to borrow a Sierra 2500HD or Crew Cab value.
Named Crew Cab height rows remain distinct
Base standard-bed Crew Cab SRW height is 80.87 inches, while AT4 and Denali Ultimate standard-bed SRW are 81.20 inches. Base long-bed Crew Cab SRW is 80.67 inches; AT4 and Denali Ultimate long-bed SRW are 80.81 inches.
The long-bed base DRW height is 80.04 inches, while Denali Ultimate DRW is 80.30 inches. AT4's long-bed DRW height cell is blank, so no value is inferred.
Box-floor lengths preserve a source-level difference
Standard-bed Crew Cab publishes 82.20 inches of inside floor length. Long-bed Crew Cab publishes 98.22 inches, while long-bed Double and Regular Cab publish 98.27 inches.
That five-hundredths-inch source difference is retained rather than normalized. Box height is 21.00 inches and wall-to-wall width is 71.40 inches throughout the reviewed pickup matrix.
| Pickup box | Floor length | Inside height | Between wheelhousings | Wall to wall |
|---|---|---|---|---|
| Crew standard bed | 82.20 in (2,088 mm) | 21.00 in (533 mm) | 51.85 in (1,317 mm) | 71.40 in (1,814 mm) |
| Crew long bed | 98.22 in (2,495 mm) | 21.00 in (533 mm) | 50.55 in (1,284 mm) | 71.40 in (1,814 mm) |
| Double/Regular long bed | 98.27 in (2,496 mm) | 21.00 in (533 mm) | 50.55 in (1,284 mm) | 71.40 in (1,814 mm) |
Interior dimensions follow cab identity
Regular Cab publishes 43.11 inches of front headroom and 44.53 inches of front legroom. Double Cab publishes 43.03/39.88 inches front/rear headroom and 44.53/35.24 inches front/rear legroom. Crew Cab normally publishes 43.03/40.12 inches and 44.53/43.40 inches.
The AT4 long-bed and Denali Ultimate long-bed Crew columns display 39.88 inches of front headroom. That source-column result stays visible instead of being replaced by the generic Crew Cab figure.
| Cab/source row | Headroom front / rear | Legroom front / rear | Shoulder room front / rear | Hip room front / rear |
|---|---|---|---|---|
| Regular Cab | 43.11 / — in | 44.53 / — in | 66.06 / — in | 60.90 / — in |
| Double Cab | 43.03 / 39.88 in | 44.53 / 35.24 in | 66.02 / 64.88 in | 61.18 / 60.24 in |
| Crew Cab base/standard named | 43.03 / 40.12 in | 44.53 / 43.40 in | 66.02 / 65.30 in | 61.18 / 60.24 in |
| AT4/Denali long-bed Crew | 39.88 / 40.12 in | 44.53 / 43.40 in | 66.02 / 65.30 in | 61.18 / 60.24 in |
Height is not a garage-fit guarantee
The published 80.04–81.20-inch span is a catalogue starting point. Tires, inflation, load, suspension state, antennas, roof equipment, snow, accessories and surface slope can change the real envelope.
Measure the highest point of the equipped truck and the lowest point along the complete approach and opening. Include a practical margin; a nominal height cell is not a clearance warranty.
Rear clearance is not the lowest underbody measurement
SRW rear-clearance cells run from 11.14 to 11.22 inches, while DRW cells run from 10.39 to 10.47 inches. The table labels these values as rear ground clearance, not as a survey of every differential, bracket, hitch or accessory.
Obstacle and carrier planning also needs approach, departure, breakover, wheelbase, tire, load and ramp geometry. Inspect the actual lowest points before relying on a clearance decision.
Wheelbase and cab-to-axle do not give turning diameter
Wheelbase ranges from 142 to 172 inches and cab-to-axle is 42.17 or 55.24 inches in the reviewed body rows. Neither is a curb-to-curb turning circle or swept-path envelope.
A dock, switchback, driveway or urban site needs steering, wheel/tire and physical-path evidence. Do not infer maneuvering clearance from wheelbase alone.
GM excludes optional equipment and accessories
GM's dimension response states that published dimensions are without optional equipment or accessories and that customer-requested equipment can cause minor changes. This limitation applies to every displayed cell.
Steps, flares, hitches, racks, auxiliary equipment, suspension changes, tires and bodies can alter the envelope. Confirm build evidence and measure the completed truck.
Dimensions do not establish weight or ratings
Cab, bed, drive and rear-wheel arrangement help identify a geometry column but do not establish curb weight, actual scale weight, payload, GVWR, GAWR, GCWR or towing capacity. Each requires its own evidence and controlling labels.
Use the distinct curb-weight guide for GM's nominal-equipment mass and the towing guide for configuration-specific capability. The ratings explainer keeps GVWR, GAWR and GCWR separate.
Pickup geometry does not cover chassis cabs or upfits
These are Sierra 3500 HD pickup columns. A chassis cab, service body, flatbed, plow, camper or other upfit needs its own completed-vehicle dimensions and operating envelope.
A shared model badge does not make pickup length, width, height or clearance portable to an altered body. Use final-stage documents and physical measurement.
U.S. and Canadian dimension records match
GM Fleet vehicle 23199 is the reviewed U.S. record and vehicle 23205 is the Canadian record. Their 12 column identities, optional-equipment note, 21 rows, paired-unit values and source blanks matched exactly on 13 September 2026.
That agreement does not certify an unseen Canadian VIN or guarantee a future order-guide revision. Recheck the applicable year and physical truck before a fit decision.
Source, date and claim limits
Numeric geometry comes from GM Fleet's official 2026 Online Order Guide, checked independently in the U.S. and Canadian Sierra 3500 HD records. GMC Canada's Sierra HD page supplies current pickup context, not replacement body cells.
No value is transferred to another year, Silverado, Sierra 2500HD, chassis cab, altered vehicle or unreviewed VIN. No weight, rating, reliability, inventory, seller, dealer count, price or offer is inferred.
Sierra 3500HD dimension questions and conclusion
How long is a 2026 Sierra 3500HD? The reviewed pickups span 236.30–266.77 inches. How wide is the dually? Crew Cab long-bed DRW is 96.60 inches and Double/Regular Cab DRW is 96.62 inches, excluding any unreported mirror envelope.
Match all source selectors, preserve blanks and small source differences, then measure the equipped truck and site. Continue with the model guide, towing-capacity tool or protected truck catalogue as appropriate.
Evidence note: manufacturer documents establish the specific facts and applications cited. Buying workflows and cost scenarios are DieselTrucks.ca editorial guidance. These pages do not publish measured failure rates or confirm the condition, recall status or capacity of a particular truck.
General educational content for Canadian diesel-pickup research. Verify the exact truck, model year, certification labels, owner manual and manufacturer documentation, and obtain qualified mechanical or towing advice where appropriate.
Sources & Further Verification
Use the exact model year, VIN, truck labels and current manufacturer documentation when moving from general research to a purchase or towing decision.