Have you ever handwritten a note and wondered if the past tense of a verb like total should have one l (totaled) or two (totalled)? Or if the verb benefit should have one t (benefited) or two (benefitted)? I consider myself a good speller, but words like that have always given me pause, and I will often consult a dictionary to check myself. However, a dictionary isn’t always handy—and even using an app on my phone eats up precious time if I’m in a hurry. Isn’t there a simple spelling rule to memorize that covers situations like these?
When to Double the Final Consonant
I’m glad you asked! Normally, you merely add –ed to a regular verb in the past tense and the past participle, but regular verbs that end in consonants like l, p, s, or t can be tricky. Remember this spelling rule for doubling the final consonant: A final consonant that is immediately preceded by an accented short vowel is doubled before the –ed ending. For example, stop→stopped (the final consonant, p, is immediately preceded by the accented short vowel o, and therefore is doubled); bat (the verb)→batted (the t is preceded by the accented short a, and therefore is doubled); rebel→rebelled (the l is preceded by the accented short e, and therefore is doubled). You get the picture.
When Not to Double the Final Consonant
If you’ve grasped the above paragraph, this surely won’t shock you: If the final consonant of the verb is not immediately preceded by an accented short vowel, do not double the consonant. For example, total→totaled (the l is not immediately preceded by an accented short vowel, so do not double it); benefit→benefited (again, the final consonant is not preceded by an accented short vowel, so do not double it). Got it? Good! 
Oh, and this works for present participles (verbs ending in –ing) as well. So we have stopping, batting, and rebelling, and we have totaling and benefiting. Fun? You betcha!
I hope that memorizing this simple spelling rule for when to double or not to double will instantly make you a better speller. If not, I guarantee double your money back.
 Regular verbs do not change form—the base word remains the same: e.g., charge, charged, charged; drop, dropped, dropped; love, loved, loved. Irregular verbs are another story. Remember, an irregular verb changes form in its past tense or past participle. E.g., give, gave, given; stink, stank, stunk; do, did, done; win, won, won.
 I’m indebted to George O. Curme’s A Grammar of the English Language—Volume I: Parts of Speech (1935) for its clear, concise explanation of this spelling rule. Keep in mind that when I refer to the “accented” short vowel, I’m referring to the syllable that is stressed.
 Of course, I’m joking here. I couldn’t possibly afford to double anyone’s nothing.
© 2018 by Dean Christensen