Sewing & Quilting Pattern Grading Calculator
Created by: Emma Collins
Last updated:
Estimate graded target measurements quickly from a base size and step increments for bust, waist, hip, and garment length.
Pattern Grading Calculator
SewingEstimate target measurements for graded sizes from a base size
Base Size and Grade Direction
Per-Step Grade Increments
Related Calculators
What is a Pattern Grading Calculator?
A pattern grading calculator estimates target body measurement specs for a new size by applying step-based grade increments to a base size.
It helps sewists and pattern designers quickly validate sizing logic before moving into full pattern-piece grading.
Pattern Grading Formulas
Target Measurement: Base Measurement ± (Size Steps × Grade Increment)
Direction: Grade up adds increments, grade down subtracts increments
Total Change: Target Measurement − Base Measurement
Per-Step Control: Bust, waist, hip, and length can use separate increments
Example Calculation
If base bust is 36 inches, bust grade is 2 inches, and you grade up 2 steps:
- Target bust = 36 + (2 × 2) = 40 inches
- The same logic applies independently for waist, hip, and length
- Use output values as your next size specification targets
Common Applications
- Indie patterns: Expand from one tested base size to a full range
- Sample development: Prepare measurement specs for fit samples
- Alteration planning: Estimate size differences before slash-and-spread work
- Brand sizing: Compare increment rules across collections
Tips for Better Grading Outcomes
- Validate increments against a real size chart before drafting
- Grade circumference and length with separate rules
- Check balance points after grading armhole and neck regions
- Always run a fit sample after major size jumps
Frequently Asked Questions
What is pattern grading?
Pattern grading scales a base size pattern up or down using measurement increments, so each size keeps similar proportions and fit intent.
Does grading change all measurements equally?
No. Bust, waist, hip, and length usually grade with different increments based on sizing standards and garment type.
Can I grade more than one size at a time?
Yes. Enter the number of size steps and the calculator applies grade increments per step to estimate the target size measurements.
Should I grade up and down with the same values?
You can, but some systems use asymmetrical rules. This tool applies your chosen increments consistently in either direction.
Is this enough for final production patterns?
It is a planning tool. Final production grading still needs pattern-level point movement, walk checks, and fit validation.
How do I pick grade increments?
Start from your brand size chart, block standards, or a commercial grading table, then test with a fit sample before full release.
Can I use this for knit and woven garments?
Yes, but knit garments may require smaller circumference increments due to stretch and negative ease behavior.
Sources and References
- Helen Joseph-Armstrong, Patternmaking for Fashion Design
- Natalie Bray, Dress Pattern Designing
- ASTM Apparel Sizing Standards, reference concepts