レンタルサーバーの容量: 失敗しない選び方と、快適なサイト運営のための重要性
レンタルサーバーを借りる時、CPUやメモリなど色々なスペックを見比べて「容量」で迷ってしまいませんか。初めてレンタルサーバーに触れると、どのくらいの容量が必要なのか、そもそも何の容量なのか、さっぱりわからないかもしれません。
In this article, I take an in-depth look at rental server capacity. Along with points to watch when starting a WordPress blog, I will help you choose the best plan. After reading this article, you should understand rental server capacity and be able to choose a plan with confidence.
レンタルサーバーの容量って一体何？ 何を保存するの？
Put simply, rental server capacity is the amount of space available for storing your website's data. Specifically, it stores the following kinds of data.
- Website files: all files needed to display the site, such as HTML, CSS, JavaScript, images, and videos
- Databases: store dynamic content such as blog posts, user information, and product information
- Email data: if you use email accounts, your sent and received emails and attachments
- Log files: server access logs, error logs, and similar records
- Backup data: backups of your website data
これらのデータがサーバーの容量を消費します。容量が足りなくなると、新しいコンテンツを追加できなくなったり、サイトの表示速度が遅くなったり、最悪の場合サイトがダウンしてしまうこともあります。
適切なサーバーの容量を選ぶための３ステップ
では、どのように適切な容量を選べば良いのでしょうか？以下の３ステップで考えてみましょう。
ステップ1 ウェブサイトの種類を考える (WordPressの場合)
ウェブサイトの種類によって必要な容量は大きく異なります。WordPressでブログを始める場合は、以下の点を考慮しましょう。
- Blog size: whether it is a small personal blog or a large blog run by multiple people.
- Content type: whether it is mainly text or uses many images and videos.
- Number of plugins: many plugins consume capacity.
- Theme weight: depending on the theme you use, it may put pressure on your capacity.
一般的な目安としては、
- Small blog (mainly text, few images): 5GB to 10GB
- Medium blog (many images, multiple plugins): 10GB to 20GB
- Large blog (including videos, many plugins): 20GB to 50GB or more
を考えておくと良いでしょう。
★ Master WordPress Plugins and Power Up Your Site: A Thorough Guide for Beginners
ステップ2 将来の成長を見積もる
ウェブサイトは作って終わりではありません。コンテンツを追加したり、アクセス数が増えたりすることで、必要な容量も増加していきます。
Assume what things will look like at least one year from now, and choose capacity with some room to spare. You can add more capacity later, but considering the trouble of changing plans, it is smoother to choose a slightly larger plan from the beginning.
WordPressの場合は、特に記事数や画像、動画が増えることを想定しておきましょう。
ステップ３ 具体的な数値で考える
上記のステップを踏まえ、具体的な数値で考えてみましょう。例えば、以下のような計算ができます。
- テキスト1ページ：約1KB
- 画像1枚：約1MB (高画質の場合はもっと大きくなります)
- 動画1分：約100MB (画質や形式により大きく変動します)
WordPressの場合は、テーマやプラグインの容量も考慮する必要があります。 これらは数十MBから数百MBになることもあります。
容量無制限プランのメリットと注意点 (WordPressの場合)
WordPressでブログを始める場合、容量無制限プランは魅力的に見えるかもしれません。しかし、前述の通り注意点も存在します。
- Watch the database size: because WordPress stores posts, settings, and other data in a database, even with unlimited capacity you may still run into database size limits.
- Backup storage: just because capacity is unlimited does not mean you can store unlimited backups. Check the backup storage limit and retention period.
★ What Is a Database? An Essential Management System for WordPress
サーバーの容量不足が引き起こす深刻な問題：具体的な影響と対策
1. コンテンツの追加が不可能に
When capacity is full, you can no longer add new content. This is a serious problem that gets in the way of website growth.
- You can no longer upload images or videos: images and videos are important elements that make a website attractive, but once capacity runs short, they can no longer be uploaded. In WordPress, you will get errors when trying to upload files to the media library, and you will no longer be able to add new images or videos.
- You can no longer create or update posts and pages: text content also uses storage space. When capacity runs short, you may no longer be able to create new posts or pages, or even update existing ones.
- You can no longer register products (in the case of an e-commerce site): on an e-commerce site, product information and images are the lifeblood of the business. Lack of capacity can prevent you from adding new products or updating existing ones, seriously affecting the business.
Countermeasure: move to a larger plan, delete unnecessary files, and optimize images (for example, through compression).
2. ウェブサイトの表示速度低下：ユーザー体験の悪化
Lack of capacity can also lead to slower website display speed. If display speed becomes slow, the user experience deteriorates and SEO is negatively affected as well.
- Increased server load: when capacity becomes tight, the load on the server increases and processing speed drops. As a result, page loading time gets longer, which means making users wait.
- Performance drops during traffic spikes: if the server is already short on capacity during periods of concentrated traffic, it can become overloaded, making the website extremely slow or, in the worst case, causing it to go down.
- Negative effect on SEO: search engines such as Google take page loading speed into account as a ranking factor. A slow website may drop in search rankings, which can lead to fewer visitors.
Countermeasure: use measures such as cache plugins, image optimization, and CDNs to improve display speed. You may also need to consider switching to a server plan that matches your traffic volume.
★ How Fast Is It? Comparing 15 Rental Servers in a Speed Ranking
3. メール送受信の停止：ビジネスコミュニケーションの阻害
Email data also consumes server capacity. When capacity runs short, you may no longer be able to send or receive email, which interferes with business communication.
- You can no longer receive email: when the inbox reaches its capacity limit, new email can no longer be received. You may miss important communication or fail to respond to customer inquiries.
- You can no longer send email: sent mail and drafts also consume capacity. Once capacity runs short, you may no longer be able to send email, which can lead to lost business opportunities.
Countermeasure: delete unnecessary emails, save email data locally, and consider using an external mail service.
4. ウェブサイトのダウン：ビジネスの停止
If lack of capacity becomes serious, in the worst case the website may go down and become inaccessible. This means business operations are effectively stopped and can lead to major losses.
- Excessive load on the server: traffic concentration while the server is already short on capacity can put excessive load on the server and cause system crashes.
- Recovery may take time: if the server goes down, recovery work may take time and the website may remain inaccessible for a long period.
Countermeasure: thoroughly implement measures that ensure stable operation, such as monitoring server resources, analyzing access logs, and choosing an appropriate server plan. Regular backups are also important.
容量不足は、ウェブサイトの運営に深刻な影響を及ぼします。これらの問題を回避するためには、適切な容量のサーバープランを選択し、定期的にウェブサイトの容量使用状況を監視することが重要です。 また、容量不足が発生した場合の対策についても事前に検討しておきましょう。
★ What Is a 503 Error? Web Traffic Jams, How to Avoid Them, and Emergency Responses
容量ごとのおすすめレンタルサーバー
30GB: Little Server
“Little Server” is a low-cost rental server. Excluding free servers, it is one of the lowest-priced rental servers for personal use. Even so, it uses NVMe SSDs to improve speed.
2025年9月30日まで初期費用無料 & リトルプランサーバー代20%OFF & 20日間無料お試し
| Server type | Shared server |
| Display speed (TTFB) | 200ms |
| Recommended plan and contract term | Mini, 12 months |
| Trial / refund guarantee | 20-day free trial |
| Monthly fee (12-month contract) | 165 yen |
| Initial administrative fee | 920 yen |
| Free domain | None |
| Support | Email (business hours not disclosed) |
| Uptime | Not disclosed |
| Server capacity | 20GB |
| Number of databases | 3 |
| Security measures | IMP |
| SSL | Free SSL, dedicated SSL (Little Plan and above) |
| Backup / restore | 7 days of automatic backups free of charge, restore free of charge |
| Number of email accounts | Unlimited |
| Email security measures | Spam filter |
| Server / website migration service | None |
| WordPress pre-installation | Yes |
| CDN | None |
*ミニプランの場合
If you want to keep the price down while securing the minimum necessary capacity, Little Server is recommended. Even the lowest-priced plan gives you 30GB. Even if you upgrade, the monthly fee stays within a few hundred yen, so if you start worrying about lack of capacity, upgrade proactively.
★ Little Server Reviews and How to Start WordPress on an Affordable Hosting Service
300GB: ConoHa WING
“ConoHa WING” is a high-speed server from GMO Internet Group, whose number of users has been rapidly increasing, and it is a service our company also uses. Because WordPress comes pre-installed when you sign up for the server, anyone can get started easily. It strikes a good balance between cost and performance, and we use it as well.
2025年8月5日までサーバー代最大53％OFF＆ドメイン2個永久無料 & 初月無料
| Server type | Shared server |
| Display speed (TTFB) | 160ms |
| Recommended plan and contract term | Basic, 12 months |
| Trial / refund guarantee | First month free |
| Monthly fee (12-month contract) | 971 yen |
| Initial administrative fee | Free |
| Free domains | Two free forever |
| Support | Phone, email, and chat (weekdays 10:00-18:00) |
| Uptime | 99.99% guaranteed |
| Server capacity | 300GB |
| Number of databases | Unlimited |
| Security measures | WAF / directory access restrictions / IP access restrictions / vulnerability diagnosis (Net de Diagnosis) / spam comment and trackback restrictions / overseas comment and trackback restrictions / overseas access restrictions |
| SSL | Free SSL / Alpha SSL / Quick Authentication SSL / Company Authentication SSL / EV SSSL |
| Backup / restore | 14 days of automatic backups / restore free of charge |
| Number of email accounts | Unlimited |
| Email security measures | Virus checking / spam filters |
| Server / website migration service | WordPress migration service from 7,678 yen Free migration tool available |
| WordPress pre-installation | Yes |
| CDN | None |
If you want enough capacity even as an individual, choose ConoHa WING. Even the lowest-priced plan gives you 300GB, so running WordPress is no problem at all.
★ Build a Homepage in 10 Minutes! ConoHa WING Reviews and How to Start WordPress
600GB: Sakura Rental Server
“Sakura Rental Server” is a shared server from Sakura Internet Inc. The company also offers managed servers. It has a good balance of performance, service, and price, so it is recommended for any corporation. Because it includes a certain amount of free CDN use depending on the plan, it can provide comfortable communications.
14-day free trial
| Server type | Shared server |
| Display speed (TTFB) | 440ms |
| Recommended plan and contract term | Standard, 12 months |
| Trial / refund guarantee | 14-day free trial |
| Monthly fee (12-month contract) | 550 yen |
| Initial administrative fee | Free |
| Free domain | None |
| Support | Business hours: 10:00-18:00 Phone callback reservations, chat, and email (reply the same day or the next business day) |
| Uptime | 99.99% |
| Server capacity | 300GB |
| Number of databases | Unlimited |
| Security measures | Website defacement notifications (paid), WAF, overseas IP address filters, prevention of unauthorized relaying, encryption, |
| SSL | Free shared SSL, dedicated SSL |
| Backup / restore | Eight generations of backups free of charge, restore free of charge |
| Number of email accounts | Unlimited |
| Email security measures | POP3, IMAP4, virus checking, simple spam filter, advanced spam filter |
| WordPress pre-installation | None |
| Server / website migration service | None |
| CDN | 100GB per month free |
法人ならサーバー容量が多いと安心です。さくらのレンタルサーバは、スタンダードプランが300GB、ビジネスプランが600GBと大容量です。
容量無制限：mixhost
“ mixhost” is a high-speed rental server from Az Pocket Co., Ltd., headquartered in Osaka. It can deliver content from servers located in San Jose on the west coast of the United States. Although it is an overseas server, the company is based in Japan, so you still get complete Japanese-language support.
2025年9月10日まで初回契約25％オフ & クラウドストレージ500GB分1年無料 ＆30日間返金保証
| Server type | Shared server / dedicated cloud server |
| Display speed (TTFB) | 150ms |
| Recommended plan and contract term | Shared server Light, 12 months |
| Trial / refund guarantee | 30-day money-back guarantee |
| Monthly fee (12-month contract) | 594 yen |
| Initial administrative fee | Free |
| Free domain | One free forever |
| Support | |
| Uptime | 99.99% guaranteed |
| Server capacity | 100GB |
| Number of databases | Unlimited |
| Security measures | WAF / DDo attack protection / malware detection and removal |
| SSL | Free dedicated SSL |
| Backup / restore | Automatic backups for 14 days on the Standard plan and above |
| Number of email accounts | Unlimited |
| Email security measures | — |
| WordPress pre-installation | Yes |
| Server / website migration service | 10,890 yen |
| CDN | None |
| Data center | San Jose, U.S. West Coast |
If you want to use a server with unlimited capacity, choose mixhost. Not only is the capacity unlimited, but the data transfer is also unlimited, so it offers excellent scalability.
★ mixhost Reviews and How to Start WordPress with Peace of Mind Thanks to Elevent Nines Backup
まとめ：最適な容量を選んで快適なWordPressブログ運営を！
Rental server capacity has a major effect on the stability and growth of a website. Use the steps introduced in this article to choose the capacity that best fits your WordPress blog and achieve smooth blog operation.
必要に応じて、サーバー管理者に相談してみるのも良いでしょう。 容量無制限プランを選ぶ場合も、メリットと注意点をよく理解した上で判断することが大切です。