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Pattern Grading for Beginners: A Step-by-Step Tutorial

Pattern Grader Team··7 min read

This tutorial walks you through grading a pattern from size 12 to size 14 using Aldrich's High-Street Fashion chart. By the end, you will understand the entire process well enough to grade any pattern across any size range.

We will work with real numbers from the Aldrich 6th Edition data — the same data that powers the Pattern Grader calculator. No guessing, no approximation.

What You Need Before Starting

  • A base pattern in size 12 (or whichever size you drafted in)
  • Pattern paper, a ruler, and a curved ruler or French curve
  • The grading increment table for your chart (we will use High-Street below)
  • A pencil and eraser — you will be redrawing lines

If you have not yet chosen a chart system, read How to Choose the Right Grading Chart first. For this tutorial, we are using the High-Street chart because its uniform increments make the math straightforward.

Step 1: Understand Your Size Chart Data

Here are the size 12 and size 14 measurements from Aldrich's High-Street chart, along with the increment (the difference between sizes):

| Measurement | Size 12 | Size 14 | Increment | |---|---|---|---| | Bust | 88 cm | 92 cm | +4 cm | | Waist | 68 cm | 72 cm | +4 cm | | Hips | 94 cm | 98 cm | +4 cm | | Back Width | 34.4 cm | 35.4 cm | +1 cm | | Chest | 32.4 cm | 33.6 cm | +1.2 cm | | Shoulder | 12.25 cm | 12.5 cm | +0.25 cm | | Nape to Waist | 41 cm | 41.4 cm | +0.4 cm | | Armscye Depth | 21 cm | 21.4 cm | +0.4 cm | | Neck Size | 37 cm | 38 cm | +1 cm | | Top Arm | 28.5 cm | 29.5 cm | +1 cm | | Sleeve Length | 58.5 cm | 59 cm | +0.5 cm | | Waist to Hip | 20.6 cm | 20.9 cm | +0.3 cm | | Waist to Knee | 58.5 cm | 59 cm | +0.5 cm | | Body Rise | 28 cm | 28.7 cm | +0.7 cm |

All these values come directly from the Aldrich data in our calculator. You can verify them by selecting "High-Street Fashion" chart and comparing sizes 12 and 14.

Notice that the increments are not uniform across measurement points. The bust, waist, and hips all increase by 4 cm, but the shoulder increases by only 0.25 cm, and the nape-to-waist length by only 0.4 cm. This is why pattern grading uses different increments per point rather than scaling.

Step 2: Identify Grade Points on Your Pattern

Grade points are the specific locations on your pattern piece where measurements are applied. For a front bodice, the key grade points are:

  1. Center front at neck — affected by nape-to-waist and neck size
  2. Shoulder point — affected by shoulder length and shoulder slope
  3. Armhole notch / side seam at armhole — affected by armscye depth and bust
  4. Side seam at waist — affected by bust (upper) and waist (lower)
  5. Center front at waist — affected by nape-to-waist length
  6. Dart points — affected by bust and dart value

Mark these points on your size 12 pattern piece with a colored pencil or small crosses.

Step 3: Calculate the Movement Per Grade Point

Each grade point moves in both the x-direction (width) and y-direction (length). Since a front bodice represents half the body, you typically apply half the full circumference increment at width points.

For our size 12 → 14 front bodice:

| Grade Point | X Movement | Y Movement | Reason | |---|---|---|---| | CF Neck | 0 cm | 0 cm | Reference point — stays fixed | | Shoulder neck point | +0.25 cm outward | 0 cm | Half neck increment | | Shoulder tip | +0.25 cm outward | 0 cm | Shoulder increment | | Armhole at side seam | +1 cm outward | +0.4 cm down | Half bust/4 + armscye depth | | Side seam at waist | +1 cm outward | +0.4 cm down | Half waist/4 + nape-to-waist | | CF at waist | 0 cm | +0.4 cm down | Nape-to-waist increment |

The exact distribution depends on your pattern structure. The key principle: circumference increments are split across the front and back pieces, and further split between center and side seam.

Step 4: Move the Grade Points

Starting from your base pattern (size 12), mark the new positions for each grade point using the movements calculated above. Use a ruler for precision — even 1 mm matters at the shoulder.

Pro tip: Work on a copy of your base pattern, not the original. If you make a mistake, you can start over without losing your base.

For each grade point:

  1. Measure the x-movement from the base point, parallel to the grainline
  2. Measure the y-movement perpendicular to the grainline
  3. Mark the new point for size 14

Step 5: Redraw the Outlines (Trueing)

This is where many beginners make errors. After moving grade points, you cannot simply connect them with straight lines. Curves — especially the armhole, neckline, and dart legs — must be redrawn smoothly.

Armhole curve: Use a French curve or flexible ruler to draw a smooth curve through the new shoulder point, armhole notch, and side seam point. The curve should maintain the same general shape as the base size but be slightly larger.

Neckline: Redraw through the new neck points with a smooth curve. Check that the front and back neckline still meet at center front/back.

Dart legs: If your pattern has bust darts, redraw the dart legs from the new bust point position to the new dart pickup points. The dart value (width at the seam line) changes per size — in the High-Street chart, it increases by 0.6 cm per size.

Side seam: Should be a smooth line from the new armhole point to the new waist point. Check that the side seam length matches between front and back pieces.

Step 6: Check Your Work

Before cutting fabric, verify these critical measurements on your graded size 14 pattern:

| Check | Expected Value | |---|---| | Bust at seamline (front + back × 2) | 92 cm | | Waist at seamline (front + back × 2) | 72 cm | | Nape to waist (back piece) | 41.4 cm | | Shoulder length | 12.5 cm | | Side seam front = side seam back | Equal |

If any measurement is more than 0.3 cm off, re-examine your grade point movements.

Step 7: Repeat for All Sizes

Once you have size 14, repeat the process for sizes 10, 8, 6, and 16 using the same increment values. In the High-Street chart, every increment is uniform across sizes 6–16, so you apply the same movement at every step.

For charts with breakpoints, like the Women's Standard chart, the increment changes at size 18. Always check the specific increment for each size step rather than assuming it is constant.

Step 8: Repeat for Every Pattern Piece

After grading the front bodice, apply the same logic to:

  • Back bodice — same bust/waist increments, different dart handling
  • Sleeves — top arm circumference and sleeve length increments
  • Skirt front and back — waist and hip increments, plus length
  • Waistband, facings, collars — grade to match the pieces they attach to

Seam lines between pieces must match after grading. Always check: front side seam = back side seam, front shoulder = back shoulder, armhole circumference = sleeve head circumference.

Using the Calculator to Speed Up

The manual process above teaches you the fundamentals. In practice, you can dramatically speed up your workflow by using the Pattern Grader calculator:

  1. Select your chart (e.g., High-Street Fashion)
  2. Set your base size (e.g., 12)
  3. Set your size range (e.g., 6–16)
  4. The calculator displays every measurement for every size, plus the increments

You still apply the increments to your physical pattern, but you skip the manual lookup entirely. The calculator shows all 14+ measurement points across your entire size range in one table.

For additional control, switch to Custom mode to modify individual increments, or Advanced mode to fine-tune your grading table per measurement.

Common Beginner Mistakes

  1. Forgetting to halve circumferences. A 4 cm bust increment becomes 1 cm at the side seam of a quarter-panel front bodice, not 4 cm.

  2. Not trueing curves. Connecting grade points with straight lines creates angular shapes. Always redraw curves with a French curve.

  3. Grading the seam allowance. Grade the seamline (stitching line), not the cutting line. Add seam allowance after grading.

  4. Ignoring the ease. The numbers in the chart are body measurements. Your garment needs ease on top. Make sure you understand ease in sewing before cutting fabric.

  5. Not fit-testing extremes. Always make a toile (test garment) in your smallest and largest graded sizes. If those fit well, intermediate sizes are almost certainly correct.

Printable Checklist

Use this checklist for each pattern piece you grade:

  • [ ] Identified chart system and verified increments
  • [ ] Marked all grade points on base pattern
  • [ ] Calculated x and y movement per grade point
  • [ ] Moved all grade points for each target size
  • [ ] Redrawn armhole curves with French curve
  • [ ] Redrawn neckline curves
  • [ ] Redrawn dart legs (if applicable)
  • [ ] Redrawn side seams and hem
  • [ ] Verified total circumference measurements
  • [ ] Verified length measurements
  • [ ] Checked seam matching between front/back
  • [ ] Added seam allowance to graded pieces

Next Steps

You have now graded your first pattern. Here is where to go next:

Pattern grading connects the creative work of design with the technical precision of manufacturing. Once you master these fundamentals, you can grade any pattern across any size range with confidence.

FAQ

Can I grade from any base size, or does it have to be the middle of the range? You can grade from any size, but starting from the middle of your range minimizes cumulative error. If you grade from size 8 up to size 20, the size 20 accumulates more grade steps than if you had started from size 14.

What if my base pattern does not match any standard chart size exactly? Use the closest chart size as your reference and adjust. For example, if your base pattern bust is 90 cm (between size 12 at 88 cm and size 14 at 92 cm), use size 12 as the base reference and note the 2 cm offset.

How long does grading take for a complete garment? For a beginner, grading a 5-piece garment across 6 sizes manually takes 2–4 hours. With practice and the calculator for quick reference, experienced graders can do it in under an hour.

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Pattern Grading for Beginners: A Step-by-Step Tutorial | Pattern Grader