Michael Turner
Quick recommendation: Record the distance from the prominent C7 vertebra (base of the neck) to the top of the iliac crest. If the result falls inside one of the ranges above, select that frame length. When the value sits near a boundary, prefer the size that places the hipbelt on the iliac crest while keeping shoulder straps about 2–3 cm clear of the acromion.
Step procedure: stand upright with relaxed shoulders wearing the usual insulating layer. Locate C7 by bending the head forward until the most prominent vertebra appears. Palpate the iliac crest at the top of the hip bones. Use a flexible tape along the spine, following natural curvature, and record the final reading in centimetres and inches.
Fit checks after selecting a frame: hipbelt should sit squarely on the iliac crest so load transfers to the hips; shoulder straps must wrap comfortably without digging and should leave ~2–3 cm clearance above the shoulder. Load lifters should form a 45°–60° angle to the torso when tightened. If hipbelt rides above the iliac crest or shoulder straps climb onto the neck, try the next size up; if shoulder straps press down and chest clearance is insufficient, try the next size down.
Practical tips: use a helper for accuracy or mirror + flexible ruler when alone; measure barefoot or in the footwear and clothing intended for typical carries. Re-check the recorded length while the carry system is loaded to confirm hipbelt placement and shoulder clearance under real conditions. Keep a tolerance of ±1 cm when comparing to manufacturers’ size charts.
Prepare: tools, clothing and correct standing posture
Use a 1.5–2.0 m flexible tape, a rigid straight edge (book, carpenter’s square or level) and a helper; mark landmarks while standing relaxed and breathe out normally.
Tools
Flexible metric tape (1.5–2.0 m). Rigid straight edge to form a vertical reference and to press gently at landmark points. Fine-tipped skin-safe pen or washable marker for temporary marks. Full-length mirror if no helper is available. Small step stool (30–40 cm) to align the straight edge at hip height. Soft measuring mat to ensure a non-slip flat surface. Aim for repeatable readings with ±0.5 cm accuracy. Store kit near other yard items such as best cylinder lawn mowers for small gardens.
Clothing & posture
Wear a close-fitting T-shirt or thin technical layer; sports bra for chest support if applicable. Remove jackets, thick sweaters, belts and heavy footwear. Stand on a level, hard surface with feet roughly hip-width apart (15–20 cm / 6–8 in between inner edges). Keep knees relaxed, weight evenly distributed between both feet, natural spinal curve, shoulders relaxed and level, chin parallel to the floor and gaze straight ahead. Arms hang naturally at sides; avoid lifting shoulders. Helper locates the C7 vertebra (most prominent neck bone) and the top of the iliac crest, holds the straight edge vertically while marks are made. Take two independent readings and record the average; hold each mark 2–3 seconds to ensure repeatability.
Find C7 vertebra: locating the top-of-back landmark
Flex the neck so the chin approaches the chest; the single largest palpable bump at the base of the neck is the C7 spinous process.
Place the pads of one or two fingers on the midline at the external occipital protuberance and slide downward until a strong, solitary protrusion is felt. A useful confirmatory sign: the cricoid cartilage sits at approximately C6, so a prominent bump immediately inferior to that level identifies C7.
Stepwise palpation
1) Have the subject tilt the head forward and relax the shoulders. 2) Palpate straight down the midline from the skull base until the first pronounced spinous process appears. 3) Ask the subject to extend and flex the head once; C7 remains the most conspicuous landmark during these movements. Mark with a removable skin marker.
Common pitfalls and remedies
Excess subcutaneous tissue, dense hair, prior neck surgery or lymphadenopathy can obscure the landmark. Use deeper, steady pressure with the fingertip pads, ask for small head flexion, or use the cricoid cartilage as an anatomical reference. If two adjacent prominences are similar, the lower one is C7; T1 lies directly below and often feels broader and less mobile.
| Action | Palpation cue | Expected identification |
|---|---|---|
| Flex head forward | Single strong midline bump appears | C7 spinous process |
| Locate cricoid cartilage | Cartilage at about C6 level | Prominence immediately below = C7 |
| Compare two prominences | Lower prominence less mobile and broader = T1 | Choose the higher, sharp bump as C7 |
After marking C7, align a flexible tape at that mark and run it down to the iliac crest; record the reading in centimeters, rounding to the nearest 0.5 cm.
Locate iliac crest: marking hip-belt reference point
Palpate the anterior superior iliac spines (ASIS) and slide thumbs posteriorly along the iliac rim until a firm, horizontal bony ridge is felt – this ridge is the iliac crest.
Palpation steps
Stand upright with feet hip-width and weight evenly distributed. Place flat thumbs on the ASIS, move thumbs straight back along the top edge of the pelvis until the highest point of the ridge is located at the lateral waist. Confirm both sides sit at the same level by comparing left and right; asymmetry greater than 1–2 cm indicates re-check while relaxed.
Marking protocol
Use a non-stretch tailor’s tape or a flat cord wrapped around the pelvis so it crosses the highest points of both crests. Keep the tape parallel to the floor and snug without compressing soft tissue. Mark centre-front and centre-back positions on the tape with a washable pen or attach safety pins at those points. Record pelvic circumference at that line and the vertical distance, in centimetres, from the iliac-crest line to any pre-marked upper-back landmark.
Verify stability by performing gentle forward flexion and side bends: if the tape shifts more than 2 cm, relocate and re-mark while standing relaxed and unloaded. The final hip-belt reference line must sit on the prominent bony rim so load transfer contacts bone rather than soft tissues.
C7-to-iliac-crest tape method: step-by-step protocol
Recommendation: perform three tape readings with an assistant, report the median in centimetres; use a soft 2 m (80 in) cloth tape, wear a light base layer and stand barefoot on a flat surface.
- Landmark confirmation: ensure C7 and iliac-crest points are marked clearly (small dot of washable marker or a skin-safe sticker).
- Subject posture: stand upright with neutral spine, feet hip-width apart, arms relaxed at sides; maintain natural head position (eyes level).
- Tape placement: anchor tape at the C7 mark, run it straight down the midline along spinous processes to the iliac-crest mark; keep tape flat against skin without digging in or lifting off.
- Tension and read: apply gentle, consistent tension so tape rests snugly but does not compress soft tissue; read the value at the point where the tape crosses the iliac-crest mark and record to the nearest 0.5 cm (or 1/8 in).
- Repeat protocol: remove and reposition tape between reads; collect three independent readings, take the median; if two readings differ by more than 1 cm, take two additional reads and use the median of the five.
- Solo alternative: use a mirror or wall-mounted marker to mark C7, then mark iliac crest while standing against the wall; step aside and measure tape length between marks laid flat on a table.
Common technique errors to avoid
- Slouching or exaggerated lumbar extension during any read.
- Placing tape off the spinal midline (tracks over rib cage or lateral musculature).
- Measuring over heavy clothing, bulky belts or thick waistbands.
- Excessive tape tension that compresses flesh and shortens the reading.
- Reading from a warped or stretched tape; use high-quality soft tapes only.
Quick sizing reference (C7→iliac-crest distance)
- Small: <43 cm (<17 in)
- Medium: 43–48 cm (17–19 in)
- Large: 49–54 cm (19–21 in)
- Extra-large: >54 cm (>21 in)
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Assess shoulder slope and strap placement: shoulder angle and strap start
Set the strap anchor so the webbing follows the natural shoulder line: place a phone inclinometer or digital angle finder on the acromion (outer shoulder bone) and align strap start to match that reading; the pad should sit over the upper deltoid and never ride on the joint.
Quick procedure
Wear a form-fitting shirt and stand relaxed with arms hanging. Have an assistant place a straight edge from the base of the neck across the acromion toward the deltoid and read the angle on a phone level or inclinometer. Mark the point where the straight edge crosses the outer shoulder – this is the functional strap-start location. Fit the shoulder strap so its inner edge runs close to the neck line and the pad wraps across the marked point without slipping forward or backward when the arms move.
Angle ranges and anchor guidance
Flat slope (0–10°): position anchor slightly medial to the acromion (≈0–10 mm) so straps sit more vertical; choose narrower straps or contoured harnesses. Moderate slope (10–20°): align anchor over the acromion; standard strap curvature is appropriate. Steep slope (>20°): move anchor lateral by ~10–25 mm and use wider, pre-shaped straps so the webbing follows the shoulder contour and avoids digging into trapezius. After adjustment, perform a dynamic check: raise arms, twist torso and simulate a load–straps should remain centered on the marked point, pad pressure distributed across the deltoid, and load lifters set roughly 30°–45° to fine-tune shoulder-pack angle.
Use measurements with sizing charts: record numbers and match frame size
Choose a frame whose published fit range includes the recorded spine-length; place the value in the central third of that range and prefer models with at least ±2 cm vertical adjustment.
Common fit ranges and hip-belt sizes
Typical manufacturer ranges (spine-length): Small = 38–43 cm (15–17 in); Medium = 43–48 cm (17–19 in); Large = 48–53 cm (19–21 in). Hip-belt size guidelines: S = 66–86 cm (26–34 in); M = 81–101 cm (32–40 in); L = 96–116 cm (38–46 in). Adjustable-frame increments often span 2 cm steps; confirm exact spec on the product sheet.
Decision rules and testing
If the recorded value falls between two labeled sizes, select the size that places the number nearer the middle of its range. Expect to choose the larger label when wearing bulky layers or carrying heavy loads; choose the smaller label when a closer, minimalist fit is desired. In-store test: set the frame to the recorded vertical setting, load the pack to a typical hiking weight, and verify shoulder harness alignment and hip-belt sit.
Recording template (copy into notes): Model / Date / Spine-length: XX cm / YY in / Hip-belt circumference: XX cm / YY in / Shoulder-angle: Z° / Selected fit label: S|M|L / Frame adjustment: +N cm or set to XX cm.
FAQ:
What’s the correct method to measure my torso for a backpack?
Measure the length of your spine from the base of the neck to the top of the hips. Stand straight and tilt your head forward to locate the C7 vertebra (the most prominent bone at the base of the neck). Place one end of a flexible tape measure at that spot, then find the top of your hip bones (iliac crest) by placing your hands on your hips and sliding your thumbs to the back; the top where your thumbs rest is the landmark. Run the tape down your spine to that point and read the number. If you prefer, use a piece of string to follow the contour of your back, then lay the string flat and measure it. Keep the tape snug but not compressing the skin, and repeat the measurement once or twice for consistency.
Can I measure my torso by myself if no one is available to help?
Yes. Use a mirror or a smartphone camera to check landmarks. Tilt your head forward and feel for the most prominent vertebra (C7); mark it lightly with a washable marker or a small piece of tape. Place your hands on your hips, thumbs toward the spine, and note where the top of the iliac crest sits — mark that point as well. Hold a flexible tape or a cord at the C7 mark, pull it down to the hip mark while watching the mirror so the tape stays centered on the spine, then read the length. If you use cord or string, transfer it to a ruler. Common pitfalls when measuring alone: letting the tape slip to one side, measuring along the shoulder blade curve instead of the spine, and wearing thick shoes or bulky clothing that changes landmarks. Wear light clothing, stand naturally, and measure twice to confirm the result.
How should I apply my torso measurement when choosing backpack size and fitting the hip belt?
Use the torso measurement to pick the right harness length from the manufacturer’s sizing chart. Packs often list small/medium/large with corresponding torso ranges; pick the size that includes your measurement. If your value falls between sizes, prefer the shorter harness and check whether the model has an adjustable back panel or a customizable harness. The hip belt should sit on the iliac crest so that the pack’s load is transferred to the hips, not the lower back. When trying a pack, tighten the hip belt so it grips the top of the hip bones, then adjust the shoulder straps just enough to bring the pack body close to your back; load lifter straps (if present) should angle back to stabilize the upper portion. Finally, test the fit while carrying typical weight for your trips — small changes in strap positions can shift how the harness length feels in use.
My torso measurement doesn’t match the manufacturer’s chart — what might be wrong and what should I do?
Possible causes: you used the wrong landmarks, measured along a shoulder blade instead of the spine, wore shoes or bulky clothing, or the brand’s sizing runs differently. Fix it by remeasuring carefully (preferably with a helper), checking the brand’s measurement method (some measure slightly differently), and trying the pack on with weight at a retailer if possible. If you must order online, compare the pack’s fit features (adjustable back, sliding harness) and choose a retailer with a good return policy.
