Ask which generic ED medication is cheaper and you'll usually be told "sildenafil." Per dose, that's true. But sildenafil works for roughly 4–6 hours and tadalafil for up to 36, which means the two drugs cover very different amounts of time per dollar. The monthly answer depends on how you actually use the medication, and for a lot of men it flips. This article runs the numbers using pricing verified in September 2026.
Per-Dose Pricing
| Drug | Roman | PeterMD | Duration |
|---|---|---|---|
| Sildenafil 25mg | ~$4/dose | — | ~4–6 hours |
| Sildenafil 50mg | ~$6/dose | — | ~4–6 hours |
| Sildenafil 100mg | ~$10/dose | $6.00–$6.25/tab | ~4–6 hours |
| Tadalafil (as-needed) | $8–$44/dose | $6.33–$7.25/tab (20mg) | Up to ~36 hours |
| Tadalafil (daily) | From ~$8/dose; gummies from ~$2+ | — | Continuous |
On a per-tablet basis, sildenafil is cheaper everywhere. At PeterMD the gap is small — under a dollar. At Roman it depends on strength: 25mg or 50mg sildenafil is clearly cheaper than tadalafil, while 100mg sildenafil at ~$10 is actually more than the ~$8 entry price for tadalafil.
Hours of Coverage Per Dollar
This is the comparison most pricing guides skip. If sildenafil gives you a 5-hour window for $6 and tadalafil gives you a 36-hour window for $7, tadalafil is delivering roughly six times the coverage for about 15% more money. Whether that matters depends on whether you want a 36-hour window.
| Option | Cost | Approx. window | Cost per hour of coverage |
|---|---|---|---|
| Roman sildenafil 50mg | ~$6 | ~5 hours | ~$1.20 |
| PeterMD sildenafil 100mg | ~$6.25 | ~5 hours | ~$1.25 |
| PeterMD tadalafil 20mg | ~$7.25 | ~36 hours | ~$0.20 |
| Roman tadalafil (from) | ~$8 | ~36 hours | ~$0.22 |
Three Usage Patterns, Three Answers
Pattern A: One planned evening, once a week
You know when you'll need it, and a single 4–6 hour window is plenty. Sildenafil is the cheaper choice, full stop. At Roman's 50mg rate that's ~$24 a month; at 25mg, ~$16.
Pattern B: A full weekend, two or three times a month
Friday night through Sunday morning might mean two or three sildenafil doses, or one tadalafil dose. Three weekends a month at three sildenafil 50mg doses each is ~$54; three tadalafil doses at PeterMD is ~$22. Tadalafil wins clearly.
Pattern C: Unpredictable, several times a week
If you'd rather not plan at all, daily low-dose tadalafil gives continuous coverage. At Roman's from-~$8 daily pricing, 30 doses is a meaningful monthly outlay, and the 7mg gummy format from ~$2+/dose is the cheaper daily route. Whether daily is worth it versus a handful of as-needed tadalafil doses is its own question — see Daily Tadalafil vs As-Needed: Cost Breakdown.
| Monthly pattern | Sildenafil route | Tadalafil route | Cheaper |
|---|---|---|---|
| 4 single evenings | 4 × ~$6 = ~$24 (Roman 50mg) | 4 × ~$7.25 = ~$29 (PeterMD) | Sildenafil |
| 3 weekends, 3 doses each | 9 × ~$6 = ~$54 | 3 × ~$7.25 = ~$22 | Tadalafil |
| 8 evenings, spread out | 8 × ~$6 = ~$48 | 8 × ~$7.25 = ~$58 | Sildenafil |
| Continuous readiness | Not practical | Daily tadalafil, 30 doses | Tadalafil (only option) |
The Non-Price Differences
Price is one input. A few others should shape the decision with your clinician:
- Timing flexibility. Tadalafil's long window removes most of the "take it and wait" planning. For many men that's worth more than the per-dose difference.
- Food. Sildenafil's absorption is noticeably slowed by a heavy, fatty meal. Tadalafil is less affected.
- Side effect profile. Both cause headache, flushing and congestion in some men. Sildenafil is more linked to temporary visual tinting; tadalafil more to back and muscle aches. Because tadalafil lasts longer, any side effects last longer too.
- Interactions. Both carry the same nitrate contraindication and similar cautions with alpha-blockers. Tadalafil's longer half-life means the interaction window is longer.
- Prostate symptoms. Daily tadalafil is also FDA-approved for BPH symptoms, which can make it a two-for-one for some men. That's a clinician conversation.
A Worked Example
Take a man prescribed 50mg sildenafil who typically has two intimate evenings a week, occasionally on consecutive nights. On sildenafil, that's about eight doses a month at ~$6 through Roman, or ~$48. Some of those consecutive-night pairs could be covered by a single tadalafil dose, so his tadalafil equivalent might be five or six doses at ~$7.25 from PeterMD, roughly $36–$44. The saving is real but modest, and it depends entirely on how often the "consecutive nights" pattern happens. If it rarely does, sildenafil stays cheaper. If it's most weeks, tadalafil pulls ahead. This is why we keep saying the answer is in your calendar, not the price list.
One more variable: side effects. Because tadalafil lasts longer, a man who gets headaches from PDE5 inhibitors may prefer sildenafil's shorter exposure even if tadalafil is cheaper on paper. Cost is one input to a decision your clinician should help you make.
Where to Buy Each
Roman offers both drugs at multiple strengths, plus daily tadalafil and the gummy format, with a full evaluation (ID, history, blood pressure reading, video visit) and free shipping. PeterMD offers sildenafil 100mg and tadalafil 20mg in fixed packs at public prices with no subscription. If you want the widest choice and a clinician to help you pick, Roman. If you already know you want 20mg tadalafil and prefer pay-per-pack, PeterMD has the lower per-tablet price. We compare the two providers directly in Roman vs PeterMD.
Quick Decision Guide
- Single planned evenings, once or twice a week: Sildenafil. Roman 25mg/50mg at ~$4–$6 is the value pick.
- Weekends or consecutive nights: Tadalafil. PeterMD 20mg at ~$6.33–$7.25 is the cheapest as-needed option; Roman from ~$8 if you want the subscription and evaluation.
- Frequent, unpredictable use: Daily tadalafil at Roman, ideally the gummy format.
- Sensitive to side effects: Sildenafil's shorter exposure may be easier to tolerate; discuss with your clinician.
- Eat before, not after: Tadalafil is less affected by food; Ro Sparks even less so.
Our Verdict — September 2026
If your use is a single planned evening, sildenafil is cheaper. If your use is a weekend, tadalafil is cheaper. Don't let per-dose price alone pick the drug; count the doses you'd actually take in a month under each and compare the totals. Roman is the easiest place to make that decision with a clinician, because it carries both drugs in every format and the evaluation is included.
Frequently Asked Questions
Is tadalafil or sildenafil cheaper?
Per dose, sildenafil is cheaper: ~$4–$10 at Roman versus tadalafil from ~$8, and ~$6.00–$6.25 versus ~$6.33–$7.25 at PeterMD. Per month, it depends on usage, because one tadalafil dose can cover a window that would take two or three sildenafil doses.
How long does tadalafil last compared to sildenafil?
Sildenafil is typically effective for about 4–6 hours. Tadalafil has a much longer half-life and can remain effective for up to 36 hours, which is why it's sometimes called the weekend pill.
Which one works faster?
Sildenafil typically takes 30–60 minutes; tadalafil is similar or slightly slower on average. Both are slowed by a heavy, fatty meal. Roman's Ro Sparks sublingual is the fastest option in its lineup, with a stated ~15-minute average onset.
Can I switch between sildenafil and tadalafil?
Yes, but under a clinician's direction. They're different molecules with different durations and interaction profiles, and you should not take them on the same day unless a prescriber has specifically arranged it.
Is daily tadalafil cheaper than as-needed?
Only if you'd otherwise use as-needed doses very frequently. Daily tadalafil means 30 doses a month; at Roman's from-~$8 pricing, that's a substantial monthly total. We cover this in our daily vs as-needed article.
Do they have different side effects?
Broadly similar — headache, flushing, congestion, indigestion. Tadalafil is more associated with back and muscle aches; sildenafil more with visual tinting. Both carry the same nitrate interaction warning.
Which should a first-time user pick?
Talk to a clinician. Many start on sildenafil because it's cheaper and shorter-acting, which makes side effects easier to manage. Men who want less planning around timing often move to tadalafil.