diff --git a/src/render/font-metrics.ts b/src/render/font-metrics.ts
index f40555c..9eed95a 100644
--- a/src/render/font-metrics.ts
+++ b/src/render/font-metrics.ts
@@ -47,7 +47,7 @@ export class FontMetrics {
         span.appendChild(this._document.createTextNode(SAMPLE_TEXT));
         container.appendChild(span);
         container.appendChild(img);
-        const baseline = img.offsetTop - span.offsetTop + 2;
+        const baseline = img.offsetTop - span.offsetTop + 1;
 
         container.removeChild(span);
         container.appendChild(this._document.createTextNode(SAMPLE_TEXT));
@@ -55,7 +55,7 @@ export class FontMetrics {
         container.style.lineHeight = 'normal';
         img.style.verticalAlign = 'super';
 
-        const middle = img.offsetTop - container.offsetTop + 2;
+        const middle = img.offsetTop - container.offsetTop + 1;
 
         body.removeChild(container);