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Free screen magnification ratio calculator. Get magnification ratio (e.g. 1.5Γ), zoom %, and effective viewing distance from base/target font px. Pair with font size accessibility.
Last updated: May 24, 2026
Need WCAG contrast at larger text? Contrast ratio calculator
Magnification Ratio
1.5x
Zoom Percent
150%
Effective Distance
40 cm
Balanced magnification range for many low-vision workflows.
Validate final settings with user testing, reflow checks, and preferred assistive tools.
We can build and embed a custom version of Screen Magnification Ratio Calculator for your brand and workflow.
Answers: what zoom is 16px to 24px and how far can I sit with this magnification.
target Γ· base β default 24Γ·16 = 1.5Γ.
Ratio Γ 100 β maps to display scaling controls.
(viewing cm Γ· ratio) Γ vision factor β default 40 cm.
Default: 16 px base β 24 px target Β· 60 cm viewing Β· moderate support β 1.5Γ Β· 150% zoom Β· effective distance 40 cm.
Ratio
1.5Γ
Zoom
150%
Effective Distance
40 cm
| Base | Target | Ratio | Zoom |
|---|---|---|---|
| 16 px | 20 px | 1.25Γ | 125% |
| 16 px | 24 px | 1.50Γ | 150% β Calculator default |
| 16 px | 32 px | 2.00Γ | 200% β WCAG 1.4.4 resize reference |
| 16 px | 48 px | 3.00Γ | 300% β High magnification β heavy reflow |
| Level | Factor | Effect on distance |
|---|---|---|
| Mild support | Γ0.90 | Slightly lower effective distance estimate |
| Moderate support | Γ1.00 | Nominal effective distance |
| High support | Γ1.15 | Higher effective distance β stronger enlargement effect modeled |
| Zoom | Guidance |
|---|---|
| <125% | May be insufficient for many low-vision tasks β increase target px |
| 125β200% | Common productive range β test reflow at 200% |
| >200% | Verify horizontal scroll, focus order, and task completion time |
Geometry-based planning for digital accessibility β validate with user testing and AT.
magnificationRatio = targetFontPx Γ· baseFontPxzoomPercent = round(ratio Γ 100)effectiveDistanceCm = round((viewingCm Γ· ratio) Γ visionFactor)1.5Γ Β· 150% Β· 40 cm effective Β· Balanced magnification range for many low-vision workflows.
2Γ Β· 200% Β· effective 30 cm Β· Balanced magnification range for many low-vision workflows.
125% Β· effective 40 cm Β· Balanced magnification range for many low-vision workflows.
3Γ Β· 300% Β· effective 20 cm Β· High magnification. Review layout reflow and line length for usability.
Mild: 36 cm Β· Moderate: 40 cm Β· High: 46 cm effective distance.
1.5Γ Β· 150% Β· effective 37 cm β ratio depends on proportion, not absolute px alone.
Share with accessibility teams, UX designers, and AT coordinators planning low-vision support.
Suggested hashtags: #LowVision #Accessibility #WCAG #Magnification #InclusiveDesign